Vascular Supply

The thyroid has an abundant blood supply (see Fig. 24-2). The arterial supply to each thyroid lobe is twofold. The superior thyroid artery arises from the external carotid artery on each side and descends several centimeters in the neck to reach the upper pole of each thyroid lobe, where it branches. The inferior thyroid artery, each of which arises from the thyrocervical trunk of the subclavian artery, crosses beneath the carotid sheath and enters the lower or midpart of each thyroid lobe. The thyroidea ima is sometimes present; it arises from the arch of the aorta and enters the thyroid at the midline. A venous plexus forms under the thyroid capsule. Each lobe is drained by the superior thyroid vein at the upper pole, which flows into the internal jugular vein; and by the middle thyroid vein at the middle part of the lobe, which enters the internal jugular or the innominate vein. Arising from each lower pole is the inferior thyroid vein, which drains directly into the innominate vein.

Nerves

The thyroid gland’s relationship to the recurrent laryngeal nerve and to the external branch of the superior laryngeal nerve is of major surgical significance because damage to these nerves leads to disability in phonation or to difficulty in breathing.⁴ Both nerves are branches of the vagus nerve.

Parathyroid Glands

The parathyroids are small glands that secrete parathyroid hormone, the major hormone that controls serum calcium homeostasis in humans. Usually, four glands are present, two on each side, but three to six glands have been found. Each gland normally weighs 30 to 40 mg, but glands may be heavier if more fat is present. Because of their small size, their delicate blood supply, and their usual anatomic position adjacent to the thyroid gland, these structures are at risk of being accidentally removed, traumatized, or devascularized during thyroidectomy.¹⁰

The upper parathyroid glands arise embryologically from the fourth pharyngeal pouch (Figs. 24-7 and 24-8). They descend only slightly during embryologic development, and their position in adult life remains constant. This gland is usually found adjacent to the posterior surface of the middle part of the thyroid lobe, often just anterior to the recurrent laryngeal nerve as it enters the larynx.

The lower parathyroid glands arise from the third pharyngeal pouch, along with the thymus; hence, they often descend with the thymus. Because they travel so far in embryologic life, they have a wide range of distribution in adults, from just beneath the mandible to the anterior mediastinum¹¹ (see Fig. 24-8). Usually, however, these glands are found on the lateral or posterior surface of the lower part of the thyroid gland or within several centimeters of the lower thyroid pole within the thymic tongue.

Parathyroid glands can be recognized by their tan appearance; their small vascular pedicle; the fact that they bleed freely when a biopsy is performed, as opposed to fatty tissue; and their darkening color of hematoma formation when they are traumatized. With experience, one becomes much more adept at recognizing these very important structures and in differentiating them from lymph nodes or fat. Frozen section examination during surgery can be helpful in their identification.

Lymphatics

A practical description of the lymphatic drainage of the thyroid gland for the thyroid surgeon has been proposed by Taylor.¹² The results of his studies, which are clinically very relevant to the lymphatic spread of thyroid carcinoma, are summarized in the following section.

1. As therapy for some individuals with thyrotoxicosis, both those with Graves’ disease and others with hot nodules

2. To establish a definitive diagnosis of a mass within the thyroid gland, especially when cytologic analysis after fine-needle aspiration (FNA) is nondiagnostic or equivocal

3. To treat benign and malignant thyroid tumors

4. To alleviate pressure symptoms or respiratory difficulties associated with a benign or malignant process

5. To remove an unsightly goiter

6. To remove large substernal goiters, especially when they cause respiratory difficulties

Solitary Thyroid Nodules

Solitary thyroid nodules are present in 4% to 9% of patients by clinical examination, and in 22% of patients by ultrasound in the United States; most are benign.¹³ Therefore, rather than operating on every patient with a thyroid nodule, the physician or surgeon should select patients for surgery who are at high risk for thyroid cancer. Furthermore, each surgeon must know the complications of thyroidectomy and must be able to perform a proper operation for thyroid cancer in a safe and effective manner or must refer the patient to a center where it can be done.

Low-Dose External Irradiation of The Head and Neck

A history of low-dose external irradiation of the head or neck is probably the most important historical fact that can be obtained in a patient with a thyroid nodule because it indicates that cancer of the thyroid is more likely (in up to 35% of cases), even if the gland is multinodular.14,15 Fortunately, treatments of low-dose radiation for thymic enlargement, tonsils, and acne have long been discontinued. However, patients who had this therapy in childhood are still seen and are still at greater risk for cancer.

High-Dose External Irradiation Therapy

High-dose external irradiation therapy, that is, more than 2000 rad, does not confer safety from thyroid carcinoma, as was previously thought.¹⁶ Rather, an increased prevalence of thyroid carcinoma, usually papillary cancer, has been found, particularly in patients with Hodgkin’s disease and other lymphomas who received upper mantle irradiation that included the thyroid gland. Usually, a dose of about 4000 to 5000 rads was given. Both benign and malignant thyroid nodules are being recognized, now that these persons survive for longer periods.¹⁷ If a thyroid mass appears, it should be treated aggressively. These patients should also be observed carefully for the development of hypothyroidism.

Risk of Ionizing Radiation

Children in the area of the Chernobyl nuclear accident have been shown to have at least a 30-fold increase in papillary thyroid cancer.¹⁸ This cancer also may be more aggressive than the usual papillary carcinoma. It is thought to result from exposure to iodine isotopes that were inhaled or that entered the food chain. The mechanism of radiation-induced thyroid cancer is thought to be caused primarily by chromosomal rearrangements such as RET/PTC.¹⁹

Diagnosis of Thyroid Nodules

A number of diagnostic modalities have been used in the past, but currently most have been superseded by FNA of the mass with cytologic analysis. In the hands of a good thyroid cytologist, more than 90% of nodules can be categorized histologically. Approximately 65% to 70% are found to be compatible with a colloid nodule. Twenty percent demonstrate sheets of follicular cells with little or no colloid. Five percent to 10% are malignant, and less than 10% are nondiagnostic. To improve the diagnostic ability of FNA, researchers are adding biomarkers to the cytologic analyses.20,21

All patients who have malignant cytologic results should be operated on. False-positive diagnoses are rare. All patients with sheets of follicular cells with little or no colloid also should undergo surgery, because their findings are compatible with a follicular neoplasm. This nodule is called a follicular nodule or an indeterminate nodule. Most, up to 90%, prove to be benign; however, a follicular carcinoma or a follicular variant of papillary cancer may exhibit the same cytologic characteristics and cannot be differentiated by FNA. Only by careful histologic examination, after operative removal of the nodule, can follicular carcinoma and adenoma be differentiated, because follicular cancers exhibit capsular and/or vascular invasion.

When the diagnosis of colloid nodule is made cytologically, the patient should be observed and not operated on unless tracheal compression or a substernal goiter is present, or unless the patient desires the benign mass to be removed. Finally, if an inadequate specimen is obtained, FNA with cytologic examination should be repeated. With small, nonpalpable masses, FNA should be performed under ultrasound guidance. Thus, FNA with cytologic assessment is the most powerful tool in our armamentarium for the diagnosis of a thyroid nodule.

In summary, the algorithm for the diagnosis of a thyroid nodule with isotope scintigraphy and ultrasonography as initial steps (Fig. 24-9) has been replaced in most hospitals, including our own, by an emphasis on the importance of early cytologic examination of the needle aspirate (Fig. 24-10). Far fewer isotope scans are currently being done because carcinomas represent only 5% to 10% of all cold nodules. This test usually is reserved for diagnosis of a “hot” nodule.

Hypothyroidism

Modest hypothyroidism is of little concern when one is treating a surgical patient; however, severe hypothyroidism can be a significant risk factor. Severe hypothyroidism can be diagnosed clinically by myxedema, as well as by slowness of affect, speech, and reflexes.²² Circulating thyroxine and triiodothyronine values are low. The serum thyroid-stimulating hormone (TSH) level is high in all cases of hypothyroidism that are not caused by pituitary insufficiency, and it is the best test of thyroid function. In the presence of severe hypothyroidism, both the morbidity and the mortality of surgery are increased as a result of the effects of both the anesthesia and the operation. Such patients have a higher incidence of perioperative hypotension, cardiovascular problems, gastrointestinal hypomotility, prolonged anesthetic recovery, and neuropsychiatric disturbances. They metabolize drugs slowly and are very sensitive to all medications. Therefore, when severe myxedema is present, it is preferable to defer elective surgery until a euthyroid state is achieved.

If urgent surgery is necessary, it should not be postponed simply for repletion of thyroid hormone. Endocrine consultation is imperative, and an excellent anesthesiologist is mandatory for success. In most cases, intravenous thyroxine can be started preoperatively and continued thereafter. In general, small doses of thyroxine are given initially to patients who are severely hypothyroid, and then the dose is gradually increased.

Hyperthyroidism

In the United States, most patients with thyrotoxicosis have Graves’ disease. In the United States, about 90% of all patients with Graves’ disease are treated with radioiodine therapy. Young patients, those with very large goiters, some pregnant women, and those with thyroid nodules or severe ophthalmopathy are commonly operated upon.

Persons with Graves’ disease or other thyrotoxic states should be treated preoperatively to restore a euthyroid state and to prevent thyroid storm, a severe accentuation of the symptoms and signs of hyperthyroidism that can occur during or after surgery. Thyroid storm results in tachycardia or cardiac arrhythmias, fever, disorientation, coma, and even death. In the early days of thyroid surgery, operations on the toxic gland were among the most dangerous surgical procedures because of the common occurrence of severe bleeding, as well as all the symptoms and signs of thyroid storm. Now, with proper preoperative preparation,²³ operations on the thyroid gland in Graves’ disease can be performed with about the same degree of safety as operations for other thyroid conditions.

In mild cases of Graves’ disease with thyrotoxicosis, iodine therapy alone has been used for preoperative preparation, although we do not recommend this approach routinely.²² Lugol’s solution or a saturated solution of potassium iodide is given for 8 to 10 days. Although only several drops per day are needed to block the release of thyroxine from the toxic thyroid gland, it is our practice to administer two drops two or three times daily. This medication is taken in milk or orange juice to make it more palatable.

Most of our patients with Graves’ disease are treated initially with the antithyroid drugs propylthiouracil or methimazole (Tapazole) until they approach a euthyroid state. Then iodine is added to the regimen for 8 to 10 days before surgery. The iodine decreases the vascularity and increases the firmness of the gland. Sometimes thyroxine is added to this regimen to prevent hypothyroidism and to decrease the size of the gland. β-Adrenergic blockers such as propranolol (Inderal) have increased the safety of thyroidectomy for patients with Graves’ disease.²³ We use them commonly with antithyroid drugs to block β-adrenergic receptors and to ameliorate the major signs of Graves’ disease by decreasing the patient’s pulse rate and eliminating the tremor. Some surgeons recommend preoperative use of propranolol alone or with iodine.²⁴ These regimens, they believe, shorten the preparation time of patients with Graves’ disease for surgery and make the operation easier because the thyroid gland is smaller and less friable than it would otherwise be.²⁴ We do not favor these regimens for routine preparation because they do not appear to offer the same degree of safety as do preoperative programs that restore a euthyroid state before surgery. Instances of fever and tachycardia have been reported in persons with Graves’ disease who were taking only propranolol. We have used propranolol therapy alone or with iodine without difficulty in some patients who are allergic to antithyroid medications. In such patients, it is essential to continue the propranolol for several weeks postoperatively. Remember that they are still in a thyrotoxic state immediately after surgery, although the peripheral manifestations of their disease have been blocked.

The advantages and disadvantages of radioiodine versus thyroidectomy as definitive treatment for Graves’ disease are listed in Table 24-1. Among our patients, we have never had a death from thyroidectomy for Graves’ disease in over 35 years. Surgical resection involves subtotal or near-total thyroidectomy (Fig. 24-11) or lobectomy with contralateral subtotal or near-total lobectomy. Currently we leave less than 2 g of thyroid tissue in the neck at the end of the operative procedure. Leaving more leads to a higher rate of recurrence.²⁵ In children and adolescents, one should consider leaving smaller remnants because the incidence of recurrence of thyrotoxicosis appears to be greater in this group. Finally, when operating for severe ophthalmopathy, we try to perform near-total or total thyroidectomy. The major benefits of thyroidectomy appear to be the speed with which normalization is achieved and a lower rate of hypothyroidism than is seen after radioiodine therapy.

Nonirradiated Patients

Any nodule suspected of being a carcinoma should be completely removed, along with surrounding tissue; this means that a total lobectomy (or lobectomy with isthmectomy) is the initial operation of choice in most patients (see Fig. 24-11). A frozen section should be obtained intraoperatively. If a colloid nodule is diagnosed, the operation is terminated. If a follicular neoplasm is diagnosed, treatment is more controversial. Differentiating follicular adenoma from follicular carcinoma, or a benign Hürthle cell tumor from Hürthle cell carcinoma, with the use of frozen section is usually very difficult. These diagnoses require careful assessment of capsular and vascular invasion, which are often difficult to evaluate on frozen section. To aid in the diagnosis, enlarged lymph nodes of the central compartment are often sampled, and a biopsy of the jugular nodes is performed. If the result is negative, two options are available: (1) stopping the operation after lobectomy, with the understanding that a second operation may be necessary to complete the thyroidectomy if a carcinoma is ultimately diagnosed; or (2) performing a resection of most of the thyroid on the contralateral side. We treat most patients with benign neoplasms with thyroxine replacement anyway, even if only one lobe has been removed. Furthermore, a second operation usually is eliminated if the lesion is later diagnosed as malignant, because the remaining small thyroid remnant can be ablated with radioiodine therapy. We discuss these options with the patient preoperatively.

Irradiated Patients

In patients with multiple thyroid nodules who have been exposed to low-dose, external irradiation of the head and neck during infancy, childhood, or adolescence, a near-total resection of the thyroid gland with biopsy of the jugular nodes is usually performed, even if a frozen section of the dominant nodule is benign. Reasons for this include the frequency of bilaterality of the disease, the known coincidence of benign and malignant nodules in the same gland, and the prevalence of papillary carcinoma in up to 35% of such patients.¹⁵ This therapy is thought to be advantageous, because small cancers can be present in the same gland, and the remaining small thyroid remnant of these patients can usually be ablated with radioiodine if a carcinoma is found on permanent section analysis. In any event, these patients require therapy with thyroid hormone. In patients with single nodules, however, we use FNA with cytology to determine the need for operation.

Patients who have received high-dose radiation to their thyroid bed (e.g., those treated with mantle irradiation for Hodgkin’s disease) are at greater risk for the development of thyroid carcinoma years later and should be monitored carefully.¹⁶ Once more, if they are operated on for nodular disease, most of the thyroid tissue should be removed, even if the dominant mass is thought to be benign.

Papillary Carcinoma

Surgical treatment for papillary carcinoma is best divided into two groups based on the clinical characteristics and virulence of these lesions.

Follicular Carcinoma

True follicular carcinomas are far less common than papillary cancer and now are rather uncommon. Remember that the “follicular variant” of papillary cancer should be classified and treated as a papillary carcinoma. Patients with follicular carcinoma are usually older than those with papillary cancer, and once more, females predominate. Microscopically, the diagnosis of follicular cancer is made when vascular and/ or capsular invasion is present. Tumor multicentricity and lymph node metastases are far less common than in papillary carcinoma. Metastatic spread of tumor often occurs by hematogenous dissemination to the lungs, bones, and other peripheral tissues.

A follicular cancer that demonstrates only microinvasion of the capsule has a very good prognosis.³⁷ In this situation, ipsilateral lobectomy is probably sufficient. However, for most patients with follicular cancer that demonstrates gross capsular invasion or vascular invasion, the ideal operation is similar to that for papillary cancer, although the rationale for its performance differs. Near-total or total thyroidectomy should be performed not because of multicentricity but rather to facilitate later treatment with radioiodine.³⁶ Remnants of normal thyroid in the neck are ablated by radioiodine, and if peripheral metastases are detected (Fig. 24-13), they should be treated with high-dose radioiodine therapy. Although lymph node metastases in the lateral region of the neck are not commonly found, a modified radical neck dissection should be performed if large palpable metastatic nodes are present.

Finally, regardless of the operation, all patients with papillary or follicular cancer should be treated for life with levothyroxine therapy in doses sufficient to suppress TSH to the appropriate level.³⁶ Care should be taken to not cause cardiac or other problems from thyrotoxicosis, however.

Hürthle Cell Tumors and Cancer

Hürthle cell tumors are thought to be variants of follicular neoplasms. They are more difficult to treat than the usual follicular neoplasms, however, for several reasons³⁸: (1) the incidence of carcinoma varies from 5.3% to 62% in different clinical series; (2) benign-appearing tumors later metastasize in up to 2.5% of patients; and (3) Hürthle cell cancers are far less likely to concentrate radioiodine than are the usual follicular carcinomas, which makes treatment of metastatic disease particularly difficult.

Of 54 patients with Hürthle cell tumors whom we treated,³⁸ 4 had grossly malignant lesions, 10 had questionable diagnoses (“intermediate” lesions) because of partial penetration of their capsule by tumor, and 40 (74%) had lesions that were thought to be benign. About half the patients had a history of low-dose external irradiation; many had separate papillary or follicular cancers in the same thyroid gland.

During a mean follow-up period of 8.4 years, three additional Hürthle cell tumors were recognized as malignant after metastases were discovered: two were originally classified as intermediate lesions, and one was in the benign-appearing group. Thus, 7 of 54 (13%) of our patients who had a Hürthle cell tumor had Hürthle cell carcinoma. One of the 7 patients with Hürthle cell cancer died of widespread metastases after 35 years, and the other 6 are currently free of disease.

We believe that treatment for these lesions should be individualized.38,39 Total thyroid ablation is appropriate for frankly malignant Hürthle cell cancers, for all Hürthle cell tumors in patients who received low-dose childhood irradiation, for patients with associated papillary or follicular carcinomas, for all large tumors, and for patients whose tumors exhibit partial capsular invasion. On the other hand, single, well-encapsulated, benign-appearing Hürthle cell tumors that are small may be treated by lobectomy and careful follow-up because the chance that they will later exhibit malignant behavior is low (2.5% in our series and 1.5% among patients described in the literature).³⁸ Nuclear DNA analysis may aid the surgeon in recognizing tumors that are potentially aggressive, because such tumors usually demonstrate aneuploidy.⁴⁰ Furthermore, increased genetic abnormalities have been shown in Hürthle cell carcinomas when compared with Hürthle cell adenomas.⁴¹

In a review of follicular cancers at the University of Chicago,³⁹ the overall mortality was 16%—twice that of papillary carcinomas. However, in non–Hürthle cell follicular cancers, the mortality was 12%, whereas in Hürthle cell cancers, it was 24%, thus demonstrating the difficulty involved in treating metastatic disease, which cannot be resected in the latter group.

Anaplastic Carcinoma

Anaplastic thyroid carcinoma remains one of the most virulent of all cancers in humans. The tumor grows very rapidly, and systemic symptoms are common. Survival for most patients is measured in months. The previously so-called small cell type, now known to be a lymphoma, is most often treated by a combination of external radiation and chemotherapy. The large cell type may be manifested as a solitary thyroid nodule early in its clinical course. If it is operated on at that time, near-total or total thyroidectomy should be performed, with appropriate central and lateral neck dissection. However, anaplastic cancer is almost always advanced when the patient is first evaluated. In such patients, surgical cure is unlikely no matter how aggressively it is pursued. In particularly advanced cases, diagnosis by needle biopsy or by small open biopsy may be all that is appropriate. Sometimes the isthmus must be divided to relieve tracheal compression, or a tracheostomy might be beneficial. Most treatment, however, has been provided by external radiation therapy, chemotherapy, or both. Hyperfractionated external radiation therapy that uses several treatments per day has some enthusiasts, but complications may be high.⁴² Radioiodine treatment is almost always ineffective because tumor uptake is absent. Although some success has been observed with doxorubicin, prolonged remissions are rarely achieved, and multidrug regimens and combinations of chemotherapy with radiation therapy are being tried.⁴³ Although remissions do occur, cures have rarely been achieved in advanced cases and new experimental techniques with tissue cultures following FNA are being tried,⁴⁴ as are new experimental drugs.

Medullary Thyroid Carcinoma

Medullary thyroid carcinoma is a C cell, calcitonin-producing tumor that contains amyloid or an amyloid-like substance. In addition to calcitonin, it may elaborate or secrete other peptides and amines such as carcinoembryonic antigen, serotonin, neurotensin, and a high-molecular-weight adrenocorticotropic hormone–like peptide. These substances may result in a carcinoid-like syndrome with diarrhea and Cushing’s syndrome, especially when widely metastatic tumor is present. Most medullary cancer of the thyroid is sporadic (about 70% to 80%), but it can be transmitted in a familial pattern. This tumor or its precursor, C cell hyperplasia, occurs as part of the multiple endocrine neoplasia type 2A (MEN2A) and type 2B (MEN2B) syndromes⁴⁵ (Fig. 24-14 and Table 24-2), or, rarely, as part of the familial medullary thyroid cancer syndrome. The MEN2 syndromes are transmitted as an autosomal dominant trait, so 50% of the offspring would be expected to have this disease. Mutations of the ret oncogene on chromosome 10 have been found to be the cause of the MEN2 syndromes.⁴⁶ These defects are germline mutations and therefore can be found in blood samples. All patients with medullary thyroid carcinoma should be screened for hyperparathyroidism and pheochromocytoma.⁴⁷ If a pheochromocytoma (or its precursor, adrenal medullary hyperplasia) is present, this growth should be operated on first because it presents the greatest immediate risk to the patient. Family members (including children) of a patient with medullary cancer of the thyroid should be screened for medullary cancer of the thyroid, especially if the tumor is bilateral or if C cell hyperplasia is present. Genetic testing for ret mutations has largely replaced screening by calcitonin in family members. However, calcitonin measurement is still useful for screening patients with a thyroid mass when FNA analysis raises the possibility of medullary thyroid cancer.

Medullary cancer spreads to the lymph nodes of the neck and mediastinum, and later disseminates to the lungs, bone, liver, and elsewhere. The tumor is relatively radioresistant, does not take up radioiodine, and is not responsive to thyroid hormone suppression. Hence, an aggressive surgical approach is mandatory. The operation of choice for medullary cancer is total thyroidectomy coupled with aggressive resection of the central, lateral, and mediastinal lymph nodes.⁴⁶ If lymph nodes of the lateral neck area contain tumor, careful and extensive modified radical neck dissection is required. Reoperations for metastatic tumor were rarely considered to be rewarding until the work of Tisell and Jansson.⁴⁸ Their work and that of others⁴⁹ demonstrated that 25% to 35% of patients with elevated circulating calcitonin levels could be rendered eucalcitoninemic after extensive, meticulous, reoperative neck dissection under magnification to remove all tiny lymph nodes. In other patients, computed tomography (CT) and magnetic resonance imaging (MRI) have localized some sites of tumor recurrence, whereas octreotide and meta-iodobenzylguanidine scanning sometimes have been helpful. Recently, positron emission tomography combined with computed tomography (PET-CT) has been successful in some patients.^49a Laparoscopic evaluation of the liver is helpful before a reoperation in that small metastatic lesions on its surface sometimes can be identified.

Cure is most likely in young children who are found by genetic screening to have a mutated ret oncogene. One hopes to operate on them when C cell hyperplasia is present and before medullary cancer has started.^49b Patients with MEN2A syndrome have a better prognosis than do those with sporadic tumor.⁴⁵ Patients with MEN2B syndrome have very aggressive tumors and rarely survive to middle age. Thus, in recent years, children 5 years of age or younger who are found by genetic screening to have MEN2A have received prophylactic total thyroidectomy to prevent the development of medullary cancer. In children with MEN2B and with a mutated ret oncogene, total thyroidectomy should be done at an earlier age, often by age 2 years, because this cancer develops at a younger age than does MEN2A.⁴⁹ With these prophylactic operations, cures are expected.

Long-term studies of medullary cancer from the Mayo Clinic group have shown that in patients without initial distant metastatic involvement and with complete resection of their medullary cancer, the 20-year survival rate, free of distant metastatic lesions, was 81%.⁵⁰ Overall 10 and 20 year survival rates were 63% and 44%, respectively. Thus, early diagnosis and complete initial resection of tumor are very important. A number of new therapies that use tyrosine kinase inhibition are now being evaluated for metastatic disease.^50a Treatment for pheochromocytoma and hyperparathyroidism is discussed elsewhere.

Lobectomy or Total Thyroidectomy

The thyroid isthmus usually is divided early in the course of the operation. The thyroid lobe is bluntly dissected free from its investing fascia and is rotated medially. The middle thyroid vein is ligated (Fig. 24-15C). The superior pole of the thyroid is dissected free, and care is taken to identify and preserve the external branch of the superior laryngeal nerve (see Fig. 24-7). The superior pole vessels are ligated adjacent to the thyroid lobe, rather than cephalic to it, to prevent damage to this nerve (Fig. 24-15D). This nerve can be visualized in over 90% of patients if it is carefully dissected.⁵¹ The inferior thyroid artery and the recurrent laryngeal nerve are identified (Fig. 24-15E). To preserve blood supply to the parathyroid glands, the inferior thyroid artery should not be ligated laterally; rather, its branches should be ligated individually on the capsule of the lobe after they have supplied the parathyroid glands (Fig. 24-15, F). The parathyroid glands are identified, and an attempt is made to leave each with an adequate blood supply while moving the gland off the thyroid lobe. Any parathyroid gland that appears to be devascularized can be minced and implanted into the sternocleidomastoid muscle after a frozen section biopsy has confirmed that it is in fact a parathyroid gland. Care is taken to try to identify the recurrent laryngeal nerve along its course if a total lobectomy is to be done. The nerve is gently unroofed from surrounding tissue, with care taken to avoid trauma to it. The nerve is in greatest danger near the junction of the trachea with the larynx, where it is adjacent to the thyroid gland. Once the nerve and parathyroid glands have been identified and preserved, the thyroid lobe can be removed from its tracheal attachments by dividing the ligament of Berry (Fig. 24-15G). The contralateral thyroid lobe is removed in a similar manner when total thyroidectomy is performed. A near-total thyroidectomy means that a small amount of thyroid tissue is left on the contralateral side to protect the parathyroid glands and recurrent nerve. Careful hemostasis and visualization of all important anatomic structures are mandatory for success. Some surgeons utilize the harmonic scalpel and believe that this decreases the time of operation. However, one must be careful not to cause damage.^51a

When closing, we do not tightly approximate the strap muscles in the midline; this allows drainage of blood superficially and thus prevents a hematoma in the closed deep space. Furthermore, we obtain better cosmesis by not approximating the platysmal muscle. Rather, the dermis is approximated by interrupted 4-0 sutures, and the epithelial edges are approximated with a running subcuticular 5-0 absorbable suture. Sterile paper tapes (Steri-Strips) then are applied and left in place for about a week. When it is needed, a small suction catheter is inserted through a small stab wound; generally it is removed within 12 hours.

Subtotal Thyroidectomy

Bilateral subtotal or near-total lobectomy is the usual operation for Graves’ disease. An alternative operation, which is equally good, combines lobectomy on one side and subtotal or near-total lobectomy on the other side. Once more, the parathyroid glands and recurrent nerves should be identified and preserved. Great care should be taken to not damage the recurrent laryngeal nerve when cutting across or suturing the thyroid lobe. At the end of the operation, several grams or less of thyroid tissue is usually left in place. The aim is to try to achieve a euthyroid state without a high recurrence of hyperthyroidism. When the operation is done for severe ophthalmopathy, however, near-total or total thyroidectomy is performed.

After thyroidectomy, even if a modified neck dissection is done for carcinoma, the patient can almost always be safely discharged on the first postoperative day. Others are kept longer if the need arises. The author does not think that it is safe to discharge a patient on the day of surgery because of the risk for bleeding; however, same-day discharge is being practiced at some centers.⁵²

Alternative Technique of Thyroidectomy

An alternative technique of thyroidectomy is practiced by some excellent surgeons6,53 and is used by the author in some operations. With this technique, the dissection is begun on the thyroid lobe and the parathyroids are moved laterally as described previously. However, the recurrent laryngeal nerve is not dissected along its length, but rather small bites of tissue are carefully divided along the thyroid capsule until the nerve is encountered near the ligament of Berry. Proponents of this technique believe that visualization of the recurrent laryngeal nerve by its early dissection may lead to greater nerve damage; however, the author believes that in many instances, seeing the nerve and knowing its pathway is safer and facilitates the dissection.

Minimally Invasive Options for Thyroidectomy

Over recent years, the development of ultrasonic shears for hemostasis and small endoscopes has allowed surgeons to perform thyroidectomies through much smaller incisions than with the use of traditional techniques. Two different approaches have been taken to minimally invasive thyroidectomies. One technique, largely popularized in areas of the Far East such as Japan, China, and Korea, involves making incisions away from the neck in hidden areas such as in the axillae or chest, or in the areola of the breast. The surgeon then creates a tunnel up to the neck, where the thyroidectomy is performed with endoscopic instruments while the endoscope is used for visualization. Approaches such as this generally are performed with low-pressure insufflation and can completely avoid any incisions on the neck itself.54–57 Although some authors utilizing such approaches have described removing large thyroid glands, most reports suggest significantly longer operative times. Perhaps of greatest concern to many American surgeons regarding these approaches is that if bleeding problems are encountered in the course of the thyroid dissection, a separate neck incision may have to be made to solve the problem. Additionally, recent reports have suggested the possibility that recurrent thyroid cancer can develop in the subcutaneous tunnel after the performance of an endoscopic thyroidectomy.^57a Such complications will have to be carefully evaluated before wide acceptance of this technique can be recommended in cases of malignancy.

An alternative technique, developed by Dr. Paolo Miccoli and more widely utilized in Europe and to a less extent in the United States, utilizes a smaller incision than usual, but it is placed in the conventional location in the neck.58,59 In general, a 1.5 to 2.0 cm incision is made in a conventional location in the neck, and after the strap muscles have been retracted from the thyroid gland, a 5-mm, 30-degree endoscope is introduced into the incision. The scope is utilized to visualize the tissue along the lateral aspect of the thyroid gland, especially for the superior pole vessels. Usually after the superior and lateral aspects of the thyroid gland have been dissected free, the parathyroid glands and the recurrent nerve are visualized, and then the thyroid lobe is delivered through the neck incision and the remainder of the operation is performed in the conventional manner through the small cervical incision. Several authors in the United States have reported good results in small series with this video-assisted approach.^60,61,61a A significant benefit of this approach is that the incision is made in the usual location, so that if any bleeding results in difficulty with visualization during the procedure, the incision can be enlarged and a conventional thyroidectomy can be completed readily. Most authors have found this approach to be similar to conventional thyroidectomy in operative time, although the small neck incision does limit the size of the thyroid gland that could be resected with the use of this technique. At this time in the United States, minimally invasive video-assisted thyroidectomy is offered in a few specialized centers for selected patients with small thyroid nodules (usually less than 3 cm) and without evidence of thyroiditis. Except in the hands of surgeons very experienced in the technique, it should not be utilized for the treatment of patients with most thyroid cancers.

Thyroid Storm

Thyroid storm reflects an exacerbation of a thyrotoxic state; it is seen most often in Graves’ disease, but it occurs less commonly in patients with toxic adenoma or toxic multinodular goiter. Clinical manifestations and management of thyroid storm are discussed elsewhere in this text.

Wound Hemorrhage

Wound hemorrhage with hematoma is an uncommon complication reported in 0.3% to 1.0% of patients in most large series. However, it is a well-recognized and potentially lethal complication.⁵² A small hematoma deep to the strap muscles can compress the trachea and cause respiratory distress. A small suction drain placed in the wound is not usually adequate for decompression, especially if bleeding occurs from an arterial vessel. Swelling of the neck and bulging of the wound can be followed quickly by respiratory impairment.

Wound hemorrhage is an emergency situation, especially if any respiratory compromise is present. Treatment consists of immediately opening the wound and evacuating the clot, even at the bedside. Pressure should be applied with a sterile sponge and the patient returned to the operating room. Later, the bleeding vessel can be ligated in a careful and more leisurely manner under optimal sterile conditions with good lighting in the operating room. The urgency of treating this condition as soon as it is recognized cannot be overemphasized if respiratory compromise is present.

Injury to The Recurrent Laryngeal Nerve

Injuries to the recurrent laryngeal nerve occur in 1% to 2% of thyroid operations when performed by experienced neck surgeons, and at a higher prevalence when thyroidectomy is done by a less experienced surgeon. They occur more commonly when thyroidectomy is done for malignant disease. Sometimes the nerve is purposely sacrificed if it runs into an aggressive thyroid cancer. Nerve injuries can be unilateral or bilateral and temporary or permanent, and they can be deliberate or accidental. Loss of function can be caused by transaction, ligation, clamping, traction, or handling of the nerve. Tumor invasion can also involve the nerve. Occasionally, vocal cord impairment occurs as a result of pressure from the balloon of an endotracheal tube as the recurrent nerve enters the larynx. In unilateral recurrent nerve injuries, the voice becomes husky because the vocal cords do not approximate one another. Shortness of breath and aspiration of liquids sometimes occur. Usually, vocal cord function returns within several months; it certainly returns within 9 to 12 months if it is to return at all. If no function returns by that time, the voice can be improved by operative means. The choice is insertion of a piece of Silastic to move the paralyzed cord to the midline; this procedure is called a laryngoplasty.

Bilateral recurrent laryngeal nerve damage is much more serious, because both vocal cords may assume a medial or paramedian position and may cause airway obstruction and difficulty with respiratory toilet. Most often, tracheostomy is required. In the authors’ experience, permanent injury to the recurrent laryngeal nerve is best avoided by identifying and carefully tracing the path of the recurrent nerve. Accidental transaction occurs most often at the level of the upper two tracheal rings, where the nerve closely approximates the thyroid lobe in the area of Berry’s ligament. If recognized, many believe that the transected nerve should be reapproximated by microsurgical techniques, although this is controversial. A number of procedures to later reinnervate the laryngeal muscles have been attempted with only limited success.⁶²

Injury to the external branch of the superior laryngeal nerve may occur when the upper pole vessels are divided (see Fig. 24-6) if the nerve is not visualized.⁹ This injury results in impairment of function of the ipsilateral cricothyroid muscle, a fine tuner of the vocal cord. This injury causes an inability to forcefully project one’s voice or to sing high notes because of loss of function of the cricothyroid muscle. Often, this disability improves during the first few months after surgery.

Recurrent Laryngeal Nerve Monitoring

In recent years, many surgeons have sought to try to further diminish the low incidence of recurrent laryngeal nerve (RLN) injury by using nerve monitoring devices during surgery. Although several devices have been utilized, all have in common some means of detecting vocal cord movement when the recurrent laryngeal nerve is stimulated. Many small series reported in the literature have assessed the potential benefits of monitoring to decrease the incidence of nerve injury.63–65 Given the low incidence of RLN injury, it is not surprising that no study has shown a statistically significant decrease in RLN injury when using a nerve monitor. The largest series in the literature by Dralle reported on a multi-institutional German study of 29,998 nerves at risk in thyroidectomy.⁶⁶ Even with a study this large, no statistically significant decrease in rates of RLN injury could be showed with nerve monitoring.

Among the problems of nerve monitoring technology are that the devices can malfunction so that the surgeon cannot depend on the device to always identify the nerve.⁶⁷ Proponents of nerve monitoring suggest that the technology might be helpful even if a statistically significant decrease in the rate of RLN cannot be shown. Although some authors have suggested that RLN monitors may be most helpful in difficult reoperative cases when significant scar tissue is encountered, this has not been shown to be the case, and some authors have advocated more routine use.^67a At this time, nerve monitoring technology in thyroid surgery should never take the place of meticulous dissection. Surgeons may choose to use the technology, but the data do not support the suggestion that nerve monitors allow thyroid surgery to be performed in a safer fashion than that performed by a good surgeon who utilizes careful technique.

Hypoparathyroidism

Postoperative hypoparathyroidism can be temporary or permanent. The incidence of permanent hypoparathyroidism has been reported to be as high as 20% when total thyroidectomy and radical neck dissection are performed, and as low as 0.9% for subtotal thyroidectomy. Other excellent neck surgeons have reported a lower incidence of permanent hypoparathyroidism.⁶⁶ Postoperative hypoparathyroidism is rarely the result of inadvertent removal of all of the parathyroid glands but is more commonly caused by disruption of their delicate blood supply. Devascularization can be minimized during thyroid lobectomy by dissecting close to the thyroid capsule, by carefully ligating the branches of the inferior thyroid artery on the thyroid capsule distal to their supply of the parathyroid glands (rather than ligating the inferior thyroid artery as a single trunk), and by treating the parathyroids with great care. If a parathyroid gland is recognized to be nonviable during surgery, it can be autotransplanted after identification by frozen section. The gland is minced into 1 to 2 mm cubes and is placed into pockets in the sternocleidomastoid muscle.

Postoperative hypoparathyroidism results in hypocalcemia and hyperphosphatemia; it is manifested by circumoral numbness, tingling of the fingers and toes, and intense anxiety that occurs soon after surgery. Chvostek’s sign appears early, and carpopedal spasm can occur. Symptoms develop in most patients when the serum calcium level is less than 7.5 to 8 mg/dL. The parathyroid hormone is low or absent in hyopoparathyroidism.

We measure the serum calcium level every 12 hours while the patient is in the hospital. Most patients are able to leave the hospital on the morning after surgery if they are asymptomatic and their serum calcium level is 7.8 mg/dL or above. Oral calcium pills are used liberally. Patients with severe symptomatic hypocalcemia are treated in the hospital with 1 g (10 mL) of 10% calcium gluconate infused intravenously over several minutes, and then with 5 g of this calcium solution placed in each 500 mL intravenous bottle to run continuously, starting with about 30 mL/hr. Oral calcium, usually as calcium carbonate (1250 mg to 2500 mg four times per day), should be started. With this treatment regimen, most patients become asymptomatic. Intravenous therapy is tapered and stopped as soon as possible, and the patient is sent home and told to take oral calcium pills. This condition is referred to as transient hypocalcemia or transient hypoparathyroidism. Serum calcium, phosphorus, and parathyroid hormone determinations are helpful.

Management of more persistent severe hypocalcemia requires the addition of a vitamin D preparation to facilitate the absorption of oral calcium. We prefer the use of 1,25-dihydroxyvitamin D (calcitriol) because it is the active metabolite of vitamin D, and it has a more rapid action. Calcitriol (0.5 mcg to 1.0 mcg) with oral calcium carbonate therapy is given four times daily for the first several days, then this priming dose of vitamin D is reduced. The usual maintenance dose for most patients with permanent hypoparathyroidism is calcitriol 0.25 to 0.5 µg daily, along with calcium carbonate, 500 mg Ca²⁺ once or twice daily, although some patients require larger doses. Serum calcium levels must be monitored carefully after discharge, and the dosage of the medications is adjusted promptly to prevent hypercalcemia and hypocalcemia. Finally, the serum parathyroid hormone level should be analyzed periodically to determine whether permanent hypoparathyroidism is truly present, because the authors and others have seen cases of postoperative tetany, perhaps caused by “bone hunger,” that later resolved completely. In such cases, circulating parathyroid hormone is normal and all therapy could be stopped. Remember that in bone hunger, serum calcium and phosphorus values are low, whereas in hypoparathyroidism, the serum calcium value is low but the phosphorus level is elevated.

McHenry^66a has shown that the incidence of complications following thyroidectomy varies greatly. In general, those surgeons with excellent training and a large experience with this operation have fewer complications, particularly after cancer procedures and reoperative surgery.

Thyroid Abnormalities

The median thyroid anlage, on rare occasions, may fail to develop. The resultant athyrosis, or absence of the thyroid gland, is associated with cretinism. The anlage also may differentiate in locations other than the isthmus and lateral lobes. The most common developmental abnormality, if looked on as such, is the pyramidal lobe, which has been reported to be present in as many as 80% of patients in whom the gland was surgically exposed. Usually, the pyramidal lobe is small; however, in Graves’ disease or in lymphocytic thyroiditis, it is often enlarged and is commonly clinically palpable. The pyramidal lobe generally lies in the midline but can arise from either lobe. Origin from the left lobe is more common than is origin from the right lobe.⁷²

Thyroid Hemiagenesis

More than 100 cases have been reported in which only one lobe of the thyroid is present.⁷³ The left lobe is absent in 80% of these patients. Often, the thyroid lobe that is present is enlarged, and both hyperthyroidism and hypothyroidism have been reported at times. Females are affected three times as often as males. Both benign and malignant nodules have been reported in this condition.⁷⁴

Other variations involving the median thyroid anlage represent an arrest in the usual descent of part or all of the thyroid-forming material along the normal pathway. Ectopic thyroid development can result in a lingual thyroid or in thyroid tissue in a suprahyoid, infrahyoid, or intratracheal location. Persistence of the thyroglossal duct as a sinus tract or as a cyst (called a thyroglossal duct cyst) is the most common of the clinically important anomalies of thyroid development. Finally, the entire gland or part of it may descend more caudally; this results in thyroid tissue located in the superior mediastinum behind the sternum, adjacent to the aortic arch or between the aorta and pulmonary trunk, within the upper portion of the pericardium, and even within the interventricular septum of the heart. Most intrathoracic goiters, however, are not true anomalies, but rather are extensions of pathologic elements of a normally situated gland into the anterior or posterior mediastinum. Each of these abnormalities is discussed in greater depth.

Ectopic Thyroid

Thyroglossal Duct Cysts

Both cysts and fistulas can develop along the course of the thyroglossal duct⁸¹ (Fig. 24-20). These cysts are the most common anomaly in thyroid development seen in clinical practice.⁸² Normally, the thyroglossal duct becomes obliterated early in embryonic life, but occasionally it persists as a cyst. Such lesions occur equally in males and females. They are seen at birth in about 25% of cases; most appear in early childhood; and the rest, about one third, become apparent only after age 30 years.⁸³ Cysts usually appear in the midline or just off the midline between the isthmus of the thyroid and the hyoid bone. They commonly become repeatedly infected and may rupture spontaneously. When this complication occurs, a sinus tract or fistula persists. Removal of a thyroglossal cyst or fistula requires excision of the central part of the hyoid bone and dissection of the thyroglossal tract to the base of the tongue (the Sistrunk procedure) if recurrence is to be minimized. This procedure is necessary because the thyroglossal duct is intimately associated with the central part of the hyoid bone (Fig. 24-21). Recurrent cysts are very common if this operative procedure is not followed.

At least 115 cases of thyroid carcinoma have been reported to originate from the thyroglossal duct.⁸² Often, in such cases, an association is noted with low-dose external irradiation of the head and neck in infancy or childhood. Almost all carcinomas have been papillary, and their prognosis is excellent. If a carcinoma is recognized, at the time of surgery the thyroid gland should be inspected for evidence of other tumor nodules, and the lateral lymph nodes should be sampled. Our practice and that of many others is to perform near-total or total thyroidectomy with appropriate nodal resection when a thyroglossal duct carcinoma is found and resected. In one series of 35 patients with papillary carcinoma arising in a thyroglossal duct cyst, the thyroid gland of 4 patients (11.4%) also contained papillary cancer.⁸² This operative procedure permits later radioiodine therapy as well.

In addition to papillary cancer, about 5% of all carcinomas arising from a thyroglossal duct cyst are squamous; rare cases of Hürthle cell and anaplastic cancer have also been reported. Finally, three families have been reported in which a total of 11 members had a thyroglossal duct cyst.⁸⁴

Lateral Aberrant Thyroid

Small amounts of histologically normal thyroid tissue are occasionally found separate from the thyroid. If these tissue elements are near the thyroid, not in lymph nodes, and are entirely normal histologically, it is possible that they represent developmental abnormalities. True lateral aberrant thyroid tissue or embryonic rests of thyroid tissue in the lymph nodes of the lateral neck region are very rare. Most agree that the overwhelming number of cases of what in the past was called “lateral aberrant thyroid” actually represent well-differentiated, metastatic thyroid cancer within cervical lymph nodes, or replacing them, rather than an embryonic rest. In such cases, we favor near-total or total thyroidectomy with a modified radical neck dissection on the side of the lymph node, probably followed by radioiodine therapy.

Several lateral thyroid masses have been reported that are said to be benign adenomas in lateral ectopic sites.85,86 The authors of these studies suggest that they may develop ectopically because of failure of fusion of the lateral thyroid component with the median thyroid. However, before this explanation is accepted, it is important to make certain that each of these lesions does not represent a well-differentiated metastasis that has totally replaced a lymph node, and in which the primary thyroid carcinoma is small or even microscopic and was not recognized.

Substernal Goiters

Developmental abnormalities may lead to the finding of thyroid tissue in the mediastinum or, rarely, even within the tracheal or esophageal wall. However, most substernal goiters undoubtedly originate in the neck and then “fall” or are “swallowed” into the mediastinum and are not embryologically determined at all.

Intrathoracic goiters have been reported to occur in 0.1% to 21% of patients in whom thyroidectomies were performed. This large variability undoubtedly is caused partly by a difference in classification among the authors, but it also may be caused by the incidence of endemic goiter. More recent series report an incidence of 2% or less.⁸⁷

Many substernal goiters are found on routine chest radiography in patients who are completely asymptomatic. Other patients may have dyspnea or dysphagia from tracheal or esophageal compression or displacement. Superior vena caval obstruction occasionally can occur with edema and cyanosis of the face,⁸⁸ and venous engorgement of the arms and face is present (Fig. 24-22). Most individuals with substernal goiters are euthyroid or hypothyroid; however, hyperthyroidism occurs as well. Although the goiters of Graves’ disease are rarely intrathoracic, single or multiple “hot” nodules may occur within an intrathoracic goiter, resulting in hyperthyroidism as part of a toxic nodular goiter.

Intrathoracic goiters are usually found in the anterior mediastinum and, less commonly, in the posterior mediastinum. In either instance, the diagnosis is suggested if a goiter can be palpated in the neck and if it appears to continue below the sternum. Rarely, however, no thyroid enlargement in the cervical area is present, and instead of being in continuity, the intrathoracic component may be attached to the cervical thyroid only by a narrow bridge of thyroid or fibrous tissue. The diagnosis of an intrathoracic thyroid mass can be made with certainty by the use of a thyroid isotope scan; however, CT or MRI also may be helpful.

Regarding therapy, we generally agree with the recommendation made by Lahey and Swinton more than 50 years ago that goiters that are definitely intrathoracic usually should be removed if the patient is a good operative risk.⁸⁹ Because of the cone-shaped anatomy of the upper thoracic outlet, once part of a thyroid goiter has passed into the superior mediastinum, it can increase its size only by descending farther into the chest. Thus, delay in surgical management may lead to increased size of the lesion, a greater degree of symptoms, and perhaps a more difficult or hazardous operative procedure.

Substernal goiters should be operated on initially through a cervical incision, because the blood supply to the substernal thyroid almost always originates in the neck and can be readily controlled in this area. Only rarely does an intrathoracic goiter receive its blood supply from mediastinal vessels; however, such a finding favors a developmental cause. Thus, in most instances, good hemostasis can be obtained by control of the superior and inferior thyroid arteries in the neck. Thus, most substernal goiters can be removed through the neck.

The authors like to divide the isthmus and the upper pole vessels early in the dissection. The affected thyroid lobe then is carefully dissected along its capsule by blunt dissection into the superior mediastinum. While gentle traction is exerted from above, the mass is elevated by the surgeon’s fingers or by blunt, curved clamps (Fig. 24-23). Often these maneuvers suffice to permit extraction of a mass from the mediastinum and into the neck area. Any fluid-filled cysts may be aspirated to reduce the size of the mass and permit its egress through the thoracic outlet. Piecemeal morcellation of the thyroid gland should not be practiced, because this occasionally has led to severe bleeding. Furthermore, several substernal goiters have been found to contain carcinoma, and this technique violates all principles of cancer surgery.

With the use of this method, the great majority of substernal thyroid glands can be removed transcervically. If the thyroid gland cannot be extracted easily from the mediastinum, however, a partial or complete sternotomy should be performed. This procedure affords direct control of any mediastinal vessels and permits resection of the thyroid gland to be carried out safely.

As in all thyroid surgery, the recurrent laryngeal nerves must be preserved and treated with care. The parathyroid glands should be identified and preserved, and the inferior thyroid artery’s branches should be ligated close to the thyroid capsule to prevent ischemia of the parathyroid glands, which might result in hypoparathyroidism.

Struma Ovarii

Ectopic development of thyroid tissue far from the neck area can lead to difficulties in rare instances. Dermoid cysts or teratomas, which are uncommon ovarian germ cell tumors, occur in female subjects of all age groups. About 3% can be classified as an ovarian struma, because they contain functionally significant thyroid tissue or thyroid tissue that occupies more than 50% of the volume of the tumor. Many more such tumors contain small amounts of thyroid tissue. Some strumae ovarii are associated with carcinoid-appearing tissue. These strumal-carcinoid tumors secrete or contain thyroid hormones as well as somatostatin, chromogranin, serotonin, glucagon, insulin, gastrin, or calcitonin.⁹⁰ Some are associated with carcinoid syndromes.

Struma ovarii sometimes is manifested as an abdominal mass lesion, often with peritoneal or pleural effusion that may be bloody. Most of these lesions synthesize and iodinate thyroglobulin poorly, and thus, despite growth of the mass, thyrotoxicosis does not develop. However, perhaps one fourth to one third of ovarian strumae are associated with thyrotoxicosis.91,92 Many of these lesions may be contributing to autoimmune hyperthyroidism in response to a common stimulator such as thyroid-stimulating immunoglobulins. In other instances, the struma alone is clearly responsible for the thyrotoxicity. An elevated free thyroxine index, a suppressed TSH value, and uptake of radioiodine in a mass in the pelvis are the obvious prerequisites for making the diagnosis.⁹³ Often, in ovarian struma, symptoms and findings of thyrotoxicosis are present in patients who have low uptake of radioiodine in their thyroid glands. Thus, a “high index of suspicion” is most important. Usually, operative resection of an ovarian tumor is indicated. After surgery, transient postoperative hypothyroidism and “thyroid storm” occasionally have been reported.

Benign thyroid adenomas in strumae are common, and about 5% manifest evidence of carcinoma.⁹⁴ Usually, these lesions are resectable, but external radiation therapy and/or ¹³¹I ablation has been advised after resection of the malignant tumors to avoid the tendency for late recurrence or metastatic disease, which sometimes has been fatal. Metastatic disease occurs in about 5% of these malignant tumors. The condition is best treated with ¹³¹I therapy, and TSH suppression should be given as for thyroid cancer originating in the usual location.

Struma Cordis

Functioning, apparently normal intracardiac thyroid tissue has been reported a few times and has been visualized by radioiodine imaging.⁹⁵ The clinical finding is usually a right ventricular mass, and the diagnosis typically has been made after operative removal.

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