This chapter focuses on the most common procedures in dermatology that include biopsy techniques as well surgical procedures for removal of benign and malignant tumors. Videos of these procedures on simulated skin, pig's feet, and in a clinical setting are available. The reader should seek hands-on supervised training to supplement the content in this section.
A skin biopsy is a diagnostic test done to gather more information than is available from the patient's history and physical examination. This information can be used to establish or confirm a diagnosis of a rash or tumor. Often clinicians hesitate to perform a biopsy. There may be concerns about the cosmetic impact on the patient, the risks associated with the procedure, or the technical aspects involved. Some disease processes are prone to sampling error and may require multiple skin biopsies for diagnosis. This is classically the case with cutaneous T-cell lymphoma or diseases with lesions of various stages or morphology.
Types of Biopsy Techniques
It is important to select the appropriate site, lesion, and technique for a biopsy to obtain an adequate sample. Having an understanding of the location of the pathology within the skin is important, for example, the epidermis, the dermal epidermal junction, deeper dermal structures, or subcutaneous dermal fat or muscle. The suspected location of the pathology will determine if a shave, punch, or an excisional biopsy is most appropriate (Table 7-1).1–4 A biopsy should not be done on lesions that are excoriated or eroded.
Table 7-1. Lesion, site, and biopsy selection for skin disorders.
|Disorder ||Procedures for Biopsy ||Lesion or Site Selection |
|Dermatoses (rash) in epidermis or superficial dermis (lesions are not indurated, sclerotic or deep). ||Punch or shave. ||Select lesions that are characteristic or typical of the rash. Avoid old resolving lesions and excoriated lesions. If possible avoid cosmetically sensitive areas, such as the central face. |
|Dermatoses in deep dermis or fat (lesions are indurated, sclerotic or deep). ||Punch, incision or excision. || |
|Vesiculobullous diseases for routine histology. ||Punch or shave. ||Biopsy new lesions 2–7 days old with bullae intact. Include the edge of blister and perilesional normal skin. |
|Vesiculobullous diseases for immunofluorescence studies. ||Punch or shave. ||For suspected vasculitis, biopsy lesional skin (the area of purpura). For suspected pemphigoid and pemphigus, biopsy perilesional skin. For suspected dermatitis herpetiformis, biopsy perilesional or normal skin. |
|Ulcers. ||Punch or incision. ||Biopsy edge of ulcer, not the necrotic center. |
|Tumors that are not suspected to be of melanocytic origin. ||Deep shave, punch, incision or excision. ||Biopsy the thickest or elevated area. |
|Tumors that are suspected to be of melanocytic origin (e.g., lentigo, nevus, atypical nevus, or melanoma). ||Deep shave, saucerization biopsy, excision or punch biopsy (for small lesions.)5,7 ||Remove ...|