10 The Punch Biopsy

The punch biopsy is an easy method for removing a round full-thickness skin specimen. It is often used to diagnose skin lesions of uncertain etiology. The main advantage of the punch biopsy over the shave technique is that it yields deeper tissue with preserved architecture for pathologic evaluation. It is also easier to perform on flat lesions for clinicians who have not mastered the art of the shave biopsy for lesions that are not elevated.

Flat lesions that are amenable to punch biopsy include inflammatory skin conditions such as drug eruptions, dermatoses, psoriasis, and cutaneous lupus (Figure 10-1). Infiltrative skin conditions such as sarcoidosis and granuloma annulare also can be diagnosed with a punch biopsy (Figure 10-2). In addition, a punch biopsy may be used to diagnose all types of skin cancers including melanoma and cutaneous lymphomas (Figure 10-3).

FIGURE 10-1 Cutaneous lupus (discoid lupus) with hypopigmentation and skin atrophy. The best method for diagnosis is a 4-mm punch biopsy.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-2 Cutaneous sarcoidosis on the face of a black woman. Although this is likely to be sarcoidosis by its appearance, a 4-mm punch biopsy was used to confirm the diagnosis.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-3 Mycosis fungoides. A previous biopsy years before was read as atopic dermatitis. When the skin disease did not respond to topical steroids and subsequently worsened, a new 4-mm punch biopsy detected cutaneous T-cell lymphoma.

(Courtesy of Debra Henderson, MD.)

A punch biopsy is one option in the diagnosis of melanoma if the entire lesion is large, making it too difficult to remove the whole lesion at the time of biopsy. In this case, the diagnostic yield will generally be best if a biopsy is performed on the darkest, most elevated, and/or most suspicious areas (Figure 10-4). Using a dermatoscope may help identify a suspicious area for the punch biopsy (see Chapter 32, Dermoscopy). If the suspicion for melanoma is high, excising the entire lesion is preferred, when possible, to improve the diagnostic yield. There are also times when a broad scoop shave may provide better tissue for the pathologist. The highest risk of using a punch biopsy to diagnose a melanoma is the risk of a false-negative result. If the lesion remains suspicious for melanoma and a punch biopsy was performed with a negative result, the remainder of the lesion should be excised for histology (see Chapter 8, Choosing the Biopsy Type).

FIGURE 10-4 A lesion suspicious for melanoma on the arm. It was too large to be fully excised easily, so a punch biopsy was performed of the darkest most raised area and the lesion was determined to be a superficial spreading melanoma with a 0.25-mm depth. The full melanoma was excised with 1-cm margins and the depth was unchanged when the full lesion was evaluated histologically.

(Courtesy of Eric Kraus, MD.)

Indications

Punch biopsy can be used to diagnose any skin condition or disease. The following are amenable to punch biopsy for diagnosis:

• Bullous diseases (Figure 10-5)

• Cicatricial alopecias (Figure 10-6)

• Inflammatory skin disease such as dermatoses, psoriasis, and vasculitis

• Infiltrative diseases such as cutaneous sarcoidosis and granuloma annulare

• Melanoma and cutaneous lymphomas (including nail melanoma)

• Oral lesions such as lichen planus (Figure 10-7)

• Vulvar diseases including vulvar intraepithelial neoplasia (VIN) (Figure 10-8).

FIGURE 10-5 Bullous pemphigoid on the back of a 57-year-old man with many intact bullae. A 4-mm punch biopsy was performed on the edge of an intact bulla and the diagnosis was confirmed.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-6 A 4-mm punch biopsy of the scalp is performed in this young woman with scarring alopecia. Subcutaneous fat is visible at the base of the biopsy. The patient was determined to have lichen planopilaris.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-7 Lichen planus with a lacy white pattern on the buccal mucosa. The presence of Wickham’s striae bilaterally in the mouth makes lichen planus likely. To establish a diagnosis histologically, a 4-mm punch biopsy of the buccal mucosa can be performed. Hemostasis can be achieved with aluminum chloride or electrocoagulation. A suture is rarely needed and is generally more uncomfortable for the patient.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-8 A 59-year-old woman with a long history of condyloma acuminata has suspicious areas of leukoplakia of the vulva. This photograph shows the vulva after two punch biopsies were performed. Both areas were found to have vulvar intraepithelial neoplasia 2 (VIN 2).

(Copyright Richard P. Usatine, MD.)

The following types of conditions may be diagnosed with a shave biopsy, but a punch biopsy can be an acceptable alternative:

• All types of nonmelanoma skin cancers and precancers (Figure 10-9)

• All benign skin neoplasms.

FIGURE 10-9 Nodular BCC on the back. A punch biopsy was used to establish the diagnosis. However, a shave biopsy would have been adequate and less invasive.

(Copyright Richard P. Usatine, MD.)

Punch biopsy can be used to remove any small skin lesion. The following lesions are often removed using this technique:

• Small nevi

• Small dermatofibromas.

 

A punch instrument can be used to create an opening in an epidermal inclusion cyst for a minimally invasive cyst removal. Some clinicians use a punch incision to remove small lipomas (see Chapter 12, Cysts and Lipomas).

Making A Diagnosis

It helps to have a good idea of the differential diagnosis before choosing the biopsy type and location. For most punch biopsies, a clinician should choose a punch size that will result in excision of the whole lesion or will provide a sample of the portion of the lesion that appears to have the worst pathology. However, for bullous disorders such as pemphigus or pemphigoid, it is best to punch the edge of the bulla to include the perilesional skin (Figure 10-10). A scoop shave under an intact bulla or at the border of a bulla may yield an equally good specimen. The goal is to keep the epidermis attached to the dermis at the edge of the bulla.

FIGURE 10-10 Bullous lichen planus on the back. A punch biopsy should include a whole intact bulla or the edge of a bulla.

(Copyright Richard P. Usatine, MD.)

When performing a biopsy on an ulcerative lesion of unknown origin, it is helpful to remove tissue from the edge of the ulcer rather than the center portion. For example, if pyoderma gangrenosum is suspected, the biopsy should include the edge of the lesion, with some perilesional skin (Figure 10-11).

FIGURE 10-11 Pyoderma gangrenosum on the leg, with diagnosis confirmed by punch biopsy of an active edge.

(Copyright Richard P. Usatine, MD.)

Additionally, before starting the biopsy the clinician should also have in mind whether the specimen will be sent for standard formalin-fixed hematoxylin and eosin (H&E) stain, direct immunofluorescence (DIF), or culture. For example, to diagnose bullous disorders, the specimen may be sent for both H&E and DIF. The biopsy for immunofluorescence is performed on perilesional skin not including the lesion itself. Suspected conditions for which a biopsy may be needed for DIF include the following:

• Discoid lupus erythematosus and SLE (Figure 10-1)

• Pemphigus (Figure 10-12)

• Bullous pemphigoid (Figure 10-5)

• Lichen planus (Figure 10-13)

• Cicatricial alopecia (Figure 10-6)

• Epidermolysis bullosa acquisita (Figure 10-14).

FIGURE 10-12 Pemphigus foliaceous on the trunk. A 4-mm punch biopsy was performed on the edge of a bulla. If direct immunofluorescence is needed, a second 4-mm punch biopsy should be performed on perilesional skin of a relatively fresh lesion.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-13 Three variations of lichen planus (LP): (A) LP on the back of a black woman. (B) Hypertrophic LP on the leg. (C) Annular LP on the breast. All three diagnoses were made with 4-mm punch biopsies sent for standard pathology.

(Copyright Richard P. Usatine, MD.)

FIGURE 10-14

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