General Principles

Curettement Biopsy

Using a sharp curette is another method of biopsy. A disposable 3-mm curette is a good choice. This size of curette is best suited for difficult areas such as in the canthal folds where the skin is thin and mobile or in areas that are difficult to access such as an ear canal or nostril. Care must be taken not to go too deep and injure vital tissue. A small lesion can be curetted off and sent to pathology (Figure 8-2).

FIGURE 8-2 Squamous cell carcinoma in the upper pinna. A 3-0 curette is able to obtain tissue more easily than a scalpel, razor, or punch in this location. However, if the curette is not adequately sharp, a scalpel may obtain a better sample.

(Copyright Richard P. Usatine, MD.)

Incisional and Excisional Biopsy

The term incisional biopsy refers to the process of excising a portion of a lesion using full-thickness excision techniques. It is used for obtaining a large sample of a large lesion, but not the entire lesion. The term excisional biopsy refers to full-thickness excision of the entire lesion. Both generally require some type of closure, which is usually done with sutures. See Chapter 11 for more detailed information about elliptical excisions.

Excision may be the biopsy method of choice for large potentially malignant lesions since a more focal biopsy may miss the malignant portion of the abnormality. Lesions highly suggestive of malignant melanoma (Figure 8-3) are often excised since the resulting specimen will provide a full-depth sample, which is needed for prognosis and treatment. The disadvantages of excising all “suspicious” lesions are that (1) it can lead to overtreatment for benign lesions and more tissue is removed than what is needed, which adds to the cost and increases scarring and other complications (e.g., excising a totally benign nevus or minimally atypical one), and (2) another surgery is often required because the initial ellipse is often performed with margins smaller than recommended for definitive treatment.

FIGURE 8-3 Full-thickness biopsy of a deep nodular melanoma. The nodular growth pattern predicted a deeper melanoma.

(Copyright Richard P. Usatine, MD.)

The excisional technique is also used to diagnose and remove dermal lesions, subcutaneous cysts and tumors (epidermal cysts and lipomas), and lesions that are too deep or too large to be removed by punch (generally greater than 5 mm in diameter) or shave. Cysts and especially lipomas may be removed with a deep linear incision rather than removing an elliptical portion of the skin (see Chapter 12, Cysts and Lipomas).

Choice of Site to Biopsy

When the decision has been made to biopsy a lesion, along with choosing the method of biopsy, the clinician must also choose the site (exact spot in the lesion) that will be biopsied.

If a “rash” or inflammatory process is present, select a “fresh” lesion that has recently appeared rather than one that has been present longer. Oftentimes, older lesions have been excoriated or secondarily infected, obscuring the primary pathology. Choose a lesion on the upper body rather than the lower body whenever possible (Figure 8-4). The histology may be easier to interpret and the healing should be more rapid. Biopsies of the lower legs are more likely to get infected or have delayed healing. Also avoid the axilla and groin if possible because these areas are more prone to infections.

FIGURE 8-4 Erythroderma in a 19-year-old woman from head to toe. A 4-mm punch biopsy was performed on her arm rather than the leg.

(Copyright Richard P. Usatine, MD.)

If a vesicular-bullous reaction is present, it is best to biopsy an intact bulla with some normal tissue (Figure 8-5). It is helpful for the pathologist to examine the edge of the bulla to characterize the exact etiology of the disease process.

FIGURE 8-5 A shave biopsy of an intact blister in a patient with suspected bullous pemphigoid.

(Copyright Richard P. Usatine, MD.)

If lesions are scattered throughout the body, choose a site where aesthetic considerations are less of a concern (e.g., avoid the face) and where scarring is less likely. The sternum, shoulders, upper back, and areas of skin tension are more likely to scar. Also, choose a lesion on the upper body rather than the lower body whenever possible.

When direct immunofluorescence (DIF) testing is to be done, biopsies are usually taken from perilesional skin (Figure 8-6). That means the biopsy will not include the bulla or erosion at all. The specimen is generally obtained with a shave or punch biopsy next to the visible pathology. DIF studies are especially helpful for autoimmune bullous diseases because antibodies will light up in the skin (Figure 8-7). They do not have to be done on the initial biopsy but may be performed to clarify and add data to a standard biopsy for hematoxylin and eosin (H&E) staining. There are only a few autoimmune diseases in which lesional skin is preferred (see Table 8-1). A 4-mm punch is adequate. It must be sent to the lab in special Michel’s media (or on saline-soaked gauze). This media should be kept in the refrigerator and can expire. If the cap is on tight and the media has just expired, it is probably still usable. See Table 8-1 for more information on the DIF biopsy.

FIGURE 8-6 A shave biopsy was performed of an intact blister including perilesional skin in a patient with suspected bullous pemphigoid. The specimen shows that the blister remained intact and there is sufficient perilesional skin to the left of the blister to cut from the specimen and send separately for direct immunofluorescence.

(Copyright Richard P. Usatine, MD.)

FIGURE 8-7 Immunofluorescence microscopy of a skin biopsy displays prominent intercellular “fish-net” deposition of C3 as well as a suprabasilar cleft within the epidermis. This confirms the diagnosis of pemphigus vulgaris.

(Courtesy of Robert Law, MD.)

TABLE 8-1 Location for Direct Immunofluorescence Biopsies

Source: Courtesy of Robert Law, MD.

If a basal cell carcinoma is suspected, it is often easy to shave off the whole lesion. If the lesion is large, almost any area can be biopsied but it is better to select a raised-up border rather than an ulcerated portion. Biopsying the latter may inaccurately provide a pathology specimen that shows only inflammation and reparative debris if not sampled deeply enough. Curettement and punch methods can also be used. An advantage with curettement is that if the tissue is necrotic, it feels “soft” with curetting and also has a classic appearance. The appearance and feel can confirm the initial impression, and treatment can be performed immediately (electrodesiccation and curettage ×3) (see Chapter 14, Electrosurgery).

If a squamous cell carcinoma is suspected, and the lesion is too large to shave off in its entirety, biopsy centrally and try to obtain a deep sample so the pathologist can determine the extent of invasion. Peripheral areas may only involve actinic change, missing the most advanced pathology. A broad deep shave is usually adequate for a biopsy. A second biopsy/excision may be needed if the pathologist reports that there is squamous dysplasia and a SCC cannot be ruled out.

If a melanoma is suspected, it is best to provide a specimen with adequate depth. Unfortunately choosing the darkest and most raised area does not guarantee the correct diagnosis. Although a full elliptical excision has been considered the gold standard, in some circumstances this is not desirable, for instance, in a large pigmented lesion on the face. In cases of suspected lentigo maligna melanoma on the face, a broad shave provides a better sample than a few punch biopsies and is less deforming that a large full-thickness biopsy. It is also just not practical to perform an elliptical excision on every potentially malignant pigmented lesion. It may be better in some instances to sample the whole lesion with a broad deep shave than to do one or more punch biopsies. Of course, sooner or later, an unsuspecting melanoma may be biopsied with a shave that misses the true depth of the lesion. Note, however, that it is far better to biopsy a lesion—regardless of the method—and find a melanoma early than to delay and procrastinate, thus missing an opportunity for early detection and treatment.⁴ Suspected early thin melanomas can easily be biopsied with a deep shave technique. When sampling a suspected thick nodular melanoma, a deep sample will be needed to find the Breslow level and plan the definitive surgery. Dermoscopy (see Chapter 32) is a tool that can help you choose the most suspicious area to biopsy in a large lesion if it is impractical to biopsy the whole lesion. Fortunately, nonexcisional biopsies do not negatively influence melanoma patient survival and, in general, do closely correlate with the true depth of the lesion.^5,6

Is it cancer?

Pigmented Lesions: Melanoma and Its Differential Diagnoses

Early detection and prompt removal of melanoma can be lifesaving. The early signs of melanoma are summarized as ABCDE, where A = asymmetry, B = borders (irregular), C = color (variegated), D = diameter (greater than 6 mm), and E = evolving and elevation (Figure 8-8).⁷ Some have suggested adding an F for a change in feeling since some melanomas present with onset of pruritus in a nevus. However, not all melanomas show these signs and not all lesions with these signs are melanomas. The dermatoscope can be used to increase your sensitivity and specificity for detecting melanoma (see Chapter 32, Dermoscopy). Whether or not a dermatoscope is used, it is incumbent on the clinician to biopsy any suspicious pigmented lesion. We cannot overemphasize that patient history is of utmost importance in the evaluation of any lesion and should never be taken lightly. If a patient is concerned that a pigmented lesion has changed, most often it deserves a biopsy/removal.

FIGURE 8-8 (A) Melanoma in situ on the arm showing asymmetry, irregular borders, variegated color, and a diameter of greater than 6 mm. (B) A broad shave biopsy of a melanoma in situ

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