FIGURE 8-17  A morpheaform basal cell carcinoma on the face. The preferred biopsy type is a punch biopsy or a deep shave. (Courtesy of the Skin Cancer Foundation, New York, NY.)

Squamous Cell Carcinomas

Squamous cell carcinoma can be difficult to diagnose by histopathology. It can easily be mistaken by the pathologist for actinic keratosis, especially if the biopsy was made along the periphery of the lesion. If an SCC is suspected, sample the central portion of the lesion using a deep shave or a punch biopsy. When performing a shave biopsy, care must be taken to get a specimen with adequate depth to enable the pathologist to render an accurate opinion (Figure 8-19). As with BCC, the physician should carefully record the site of biopsy. For large lesions, particularly those in or around the oral cavity and ears, it is important to check for lymphadenopathy. Prompt treatment after diagnosis of SCC is essential because some of these lesions have the potential for metastasis (see Chapter 34).

FIGURE 8-19  Squamous cell carcinoma on the finger. The first two shave biopsies did not reveal a squamous cell carcinoma. A third deeper and broader shave biopsy was adequate to make the diagnosis. The lesson here is not to believe a benign biopsy result if you believe the lesion is truly cancer. The thick keratin and the fear of damaging the finger’s function prevented a correct diagnosis with the first two biopsies. (Copyright Richard P. Usatine, MD.)

Amelanotic Melanomas

Everyone is concerned about missing an amelanotic melanoma clinically. Rest assured that even the best specialist clinicians will misdiagnose these lesions clinically. It is far better to biopsy a lesion of uncertain etiology than to just observe it (Figure 8-20).

INFLAMMATORY DISORDERS

Various inflammatory disorders present as unknown rashes, and a punch biopsy will provide adequate tissue for diagnosis (e.g., lichen planus, psoriasis and cutaneous lupus erythematosus). The typical malar rash of systemic lupus erythematosus (SLE) in a patient with a strongly positive antinuclear antibody (ANA) does not

FIGURE 8-18  Pigmented BCC on the temple of an elderly woman. A deep shave biopsy was performed in case this turned out to be a melanoma. While doing the shave biopsy, the tissue below the lesion was viewed to make sure that the shave was below the pigment. With the similar morphology throughout, a punch biopsy should have provided adequate initial information whether or not this turned out to be a BCC or melanoma. (Copyright Richard P. Usatine, MD.)

FIGURE 8-20  An amelanotic melanoma about to be excised. The diagnosis was not obvious but the elliptical excision provided great tissue for diagnosis. (Courtesy of E. J. Mayeaux.)

FIGURE 8-21  An erythematous eruption in photoexposed areas turned out to be subacute cutaneous lupus erythematosus proven by a 4-mm punch biopsy on the anterior chest. (Copyright Richard P. Usatine, MD.)

require a biopsy for diagnosis. However, some cases of cutaneous lupus may need a biopsy for diagnosis (Figure 8-21). Lichen planus presents with different morphologies from atrophic to hypertrophic, from solid to bullous. A punch biopsy is needed for definitive diagnosis (Figure 8-22). A 4-mm punch biopsy is usually preferred (see Chapter 10, The Punch Biopsy).

FIGURE 8-22  An atrophic variant of lichen planus in a 36-year-old man proven by a 4-mm punch biopsy. The biopsy was essential for diagnosis of this rare variant of lichen planus. (Copyright Richard P. Usatine, MD.)

FIGURE 8-23  Erythema nodosum is a panniculitis. Therefore, a punch biopsy should be deep and obtain subcutaneous fat. This patient had erythema nodosum leprosum. (Copyright Richard P. Usatine, MD.)

Almost all inflammatory dermatoses have a dermal component. Punch biopsy is necessary to preserve the dermal architecture so the dermatopathologist can evaluate the cellular infiltrate, both as to its nature and its pattern. In most cases in which a punch biopsy is indicated, the biopsy need only go through the dermis, and the specimen is cut off at the top of the subcutaneous fat. However, to diagnose erythema nodosum (Figure 8-23), the punch specimen should include as much of the subcutaneous fat as possible. This is because erythema nodosum is really a panniculitis, with the overlying dermis secondarily involved.

INFILTRATIVE DISORDERS

Infiltrative disorders, such as granulomas, also require a punch rather than a shave biopsy to deliver a suitable specimen for dermatopathologic examination. Examples of infiltrative disorders include sarcoidosis (Figure 8-24), cutaneous T-cell lymphoma (Figure 8-25), and granuloma annulare (Figure 8-26). Morphea (Figure 8-27) and lichen sclerosis (Figure 8-28) are diagnosed with punch biopsies as well.

ERYTHRODERMA

Erythroderma is a dangerous dermatologic condition in which the skin becomes red and begins to peel off in flakes (Figure 8-29). The impaired skin barrier makes the person vulnerable to dehydration and infection. It is the dermatologic manifestation of a number of underlying disease processes, including various forms of dermatitis, drug reactions, and lymphoproliferative disorders. The key to proper diagnosis and treatment is contingent on a good biopsy.

A short differential diagnosis of erythroderma includes:

•Psoriasis

•Drug reaction

FIGURE 8-24  Sarcoidosis is an infiltrative disease found often on the face and nasal rim. Whereas the morphology and distribution in a black woman is highly suggestive of sarcoidosis, it is best to confirm the diagnosis with a biopsy. In this case it is best to biopsy the lesion below the nose rather than risk anatomic distortion of the nasal rim. A punch biopsy is generally preferred. (Copyright Richard P. Usatine, MD.)

•Atopic and contact dermatis

•Seborrheic dermatitis

•Dermatomyositis

•Cutaneous T-cell lymphoma (CTCL)

•Idiopathic.

Because erythroderma covers most of the body, there are many areas from which to choose for the biopsy.

FIGURE 8-25  Cutaneous T-cell lymphoma in the more advanced tumor stage. A 4-mm punch biopsy was sufficient to make the diagnosis (Courtesy of UTHSCSA Division of Dermatology.)

FIGURE 8-26  Disseminated granuloma annulare on the arm. A 4-mm punch biopsy of a granulomatous ring is recommended if the diagnosis is in question. (Copyright Richard P. Usatine, MD.)

Like most diagnostic challenges, the 4-mm punch biopsy is the standard method for obtaining tissue. Choose an area on the upper body such as the arm or trunk with significant skin involvement. If there are pustules as in possible pustular psoriasis, biopsy a pustule (Figure 8-30). Send this for a stat pathology consult while initiating treatment. Many patients will need hospitalization, but it is usually easiest to do the biopsy in the office before transferring the patient to the hospital.

BULLOUS LESIONS

Many bullous lesions are seen with bullous impetigo to pemphigus and bullous pemphigoid (Figure 8-31).

FIGURE 8-27  Morphea (localized scleroderma) on the back of a man. A 4-mm punch biopsy was used to make the diagnosis. (Copyright Richard P. Usatine, MD.)

FIGURE 8-28  Lichen sclerosis at atrophicus on the vulva and perineum. The clinical impression was confirmed with a 3-mm punch biopsy that was left open to heal by second intention. Sutures in this area can be very uncomfortable and the tissue heals well without suturing. The whitest area was chosen to rule out vulvar intraepithelial neoplasia. (Copyright Richard P. Usatine, MD.)

Although bullous impetigo can be diagnosed and treated based on history and physical exam, the autoimmune forms of bullous diseases should be biopsied while initiating treatment. These diseases are often treated with prolonged courses of oral steroids and immunosuppressive medications, so it is essential to have the correct diagnosis from the start. Start with one 4-mm punch biopsy of an established lesion including the edge of the blister. A shave biopsy is an alternative as long as the epidermis of the blister stays attached to the specimen. If possible biopsy a new blister and remove the whole lesion. This is sent in formalin for H&E staining. Further information is obtained with a 4-mm punch biopsy for DIF. Biopsy the perilesional skin and send the specimen in Michel’s media (see earlier discussion under Choice of Site to Biopsy). If this media is not available, send the specimen in a sterile urine cup on top of a sterile gauze soaked with sterile saline and alert the pathologist that the specimen is not in Michel’s media. See Table 8-1 for more detailed information on where and how to biopsy tissue for DIF.

SUSPECTED INFECTIOUS RASH

In most cases of common infectious diseases the diagnosis can be made clinically, with a KOH preparation

FIGURE 8-29  Erythroderma in a 19-year-old woman. A stat punch biopsy was done to obtain a diagnosis. (Copyright Richard P. Usatine, MD.)

or with a culture. Sometimes a 4-mm punch biopsy may be needed for bacterial and fungal stains. Fungal infections are often diagnosed with periodic acid Schiff (PAS) stains. If the rash might have an infectious origin and standard biopsies in formalin are not providing the answer, send fresh tissue in a sterile urine cup on top of a sterile gauze soaked with sterile saline and ask for other studies including AFB stains and cultures.

FIGURE 8-30  A close-up of a small pustule in a 67-year-old woman with erythroderma. A 4-mm punch biopsy of this site made the diagnosis of pustular psoriasis. (Copyright Richard P. Usatine, MD.)