Incidentally Discovered Mass Lesions (Case 35)

Published on 24/06/2015 by admin

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Last modified 24/06/2015

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Incidentally Discovered Mass Lesions (Case 35)

Tami Berry MD Joseph J. Muscato MD

Case: A 42-year-old woman presented to her family physician with right lower quadrant discomfort of 2 days’ duration and was sent for a CT scan of the abdomen and pelvis to “rule out appendicitis.” The CT scan revealed a normal appendix and no acute abnormality. The patient’s acute problem was self-limited, and she felt better the following day. However, the radiologist noted an “incidental finding,” and the family physician was promptly notified.

Differential Diagnosis

image

 

Speaking Intelligently

An incidentally discovered mass, or “incidentaloma,” will be experienced by every physician, both during training and during practice. The unsuspected mass that appears on imaging done for some other purpose can present a great conundrum for clinicians. As our population ages and both the frequency and resolution of radiologic imagery increase, there will consequently be more incidental mass findings. Clinicians must be prepared to manage these safely and effectively. The focus of evaluation is a balance of minimizing untoward stress or risk to the patient without missing something important that requires additional diagnostic evaluation.

PATIENT CARE

Clinical Thinking

• Incidental lesions force the clinician to “work backwards,” by re-examining the patient’s history and clinical picture to determine whether the finding validates a concern, warrants a more extensive evaluation, or requires surveillance.

History and Physical Examination

• Specific points of history, possible findings on examination, and specific tests for diagnosis are covered separately under Clinical Entities below.

Clinical Entities Medical Knowledge

Adrenal Mass

An adrenal “incidentaloma” is an adrenal mass > 1 cm in size that is discovered on radiologic imaging performed for reasons unrelated to the adrenal glands.

TP

Prevalence of an incidental adrenal mass found on abdominal CT imaging is 4% and in those aged ≥ 70 years is 7%. A compelling theory is that as people age there is increased likelihood of undergoing imaging and that the effects of local ischemia and atrophy lead to the development of cortical nodules or lesions.

Dx

Three questions should be investigated when evaluating an incidental adrenal mass: (1) Is the tumor active or functional? (2) Does the radiologic phenotype suggest malignancy? (3) Is there a history of a previous malignant lesion?

Radiologic phenotypic features that aid our characterization of the mass include size, shape, symmetry, and heterogeneity or homogeneity of tissue density measured in Hounsfield units (HU). Adenomas tend toward smooth edges, symmetry, and homogeneous density.

FNA of the mass is recommended only in patients with suspicious radiologic phenotypic malignant features in the background of a prior oncologic process. FNA is also reasonable in patients refusing the recommendation for surgery, if the findings would alter management. FNA should proceed only after a pheochromocytoma has been ruled out, as hypertensive crisis and physiologic collapse may occur.

Tx

If any of the above diagnostic questions can be answered affirmatively, then a multidisciplinary approach is prudent, inclusive of an endocrinologist, surgeon, and medical oncologist. Refer to the following Clinical Entities on specific workup for hypercortisolism, hyperaldosteronism, pheochromocytoma, and primary adrenocortical adenocarcinoma. Excess production of androgen or sex hormones is rarely asymptomatic and is not included in our discussion on incidental adrenal masses.

Incidental adrenal lesions that are inactive and measuring over 4–6 cm warrant both radiologic and biochemical follow-up. Radiologic follow-up is fashioned to elicit whether the lesion is either dormant or rapidly proliferating; radiologic evaluations are recommended at 6-, 12-, and 24-month intervals. Annual biochemical assays, over a 5-year duration, are warranted for any nonfunctional adrenal mass measuring over 4–6 cm because there is a positive relationship between adrenal mass size and hormonal functionality. See Cecil Essentials 67.

Cortisol-Secreting Adrenal Mass

These lesions display autonomous glucocorticoid production and can be termed subclinical hypercortisolism (SCS) when the patient is asymptomatic or lacks the signs and symptoms of the Cushing syndrome.

TP

SCS is the most common biochemical abnormality detected in patients with an adrenal incidentaloma (9%) and can be accompanied by arterial hypertension, obesity, dyslipidemia, glucose intolerance, and osteoporosis.

Dx

An overnight 1-mg dexamethasone suppression test is done to screen for elevated cortisol levels in patients with suspected Cushing syndrome or SCS; a serum cortisol > 5 µg/dL after a 1-mg (low-dose) dexamethasone suppression test is considered positive (specificity 91%). If the screening test is positive, then confirmatory testing is warranted. This can be done with measurement of a 24-hour urinary free cortisol (UFC), midnight salivary cortisol, or a 48-hour 2-mg (high-dose) dexamethasone suppression test.

Tx

Medical therapy remains the mainstay of treatment. Surgical adrenalectomy is reserved for patients who are young (<40 years) and those with recent onset or worsening hypertension, glucose intolerance, dyslipidemia, obesity, or osteoporosis. See Cecil Essentials 67.

 

Aldosterone-Secreting Adrenal Mass

Almost 1% of incidental adrenal masses are aldosterone-secreting adenomas, warranting biochemical evaluation in those with hypertension or other signs or symptoms consistent with autonomous aldosterone production.

TP

Patients with hypertension should undergo evaluation for hyperaldosteronism. In those with hypokalemia and mild hypernatremia, you may elicit a history of nocturia, polyuria, muscle cramping, and palpitations.

Dx

Measure the ambulatory morning plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio while the patient is upright. A PAC/PRA ratio > 20 is consistent with hyperaldosteronism (note: spironolactone and mineralocorticoid antagonists can result in false positive results). A positive screen is followed with confirmatory measurement of mineralocorticoid secretory autonomy with oral sodium loading, IV saline infusion, or a fludrocortisone suppression test.

Tx

Any lesion autonomously producing aldosterone should be referred for surgical removal. See Cecil Essentials 13, 67.

 

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Pheochromocytoma

Pheochromocytoma is associated with high rates of morbidity and mortality.

TP

History may include episodic (paroxysmal) rapid heart rate, tremor, headache, or diaphoresis. These episodes may be precipitated by anxiety, extreme postural changes, or medications (metoclopramide and anesthetic agents).

Dx