Punch biopsy of the skin.

Skin biopsy is one of the most important diagnostic tests for skin disorders. Punch biopsy is considered the primary technique for obtaining diagnostic full-thickness skin specimens. It requires basic general surgical and suture-tying skills and is easy to learn. The technique involves the use of a circular blade that is rotated down through the epidermis and dermis, and into the subcutaneous fat, yielding a 3- to 4-mm cylindrical core of tissue sample. Stretching the skin perpendicular to the lines of least skin tension before incision results in an elliptical-shaped wound, allowing for easier closure by a single suture. Once the specimen is obtained, caution must be used in handling it to avoid crush artifact. Punch biopsies are useful in the work-up of cutaneous neoplasms, pigmented lesions, inflammatory lesions and chronic skin disorders. Properly administered local anesthesia usually makes this a painless procedure.