Skin biopsy is a technique

in which a lesion is removed to render a microscopic diagnosis (though occasionally it may be sufficient for “treatment” of your condition). It is usually done under local anesthetic in the dermatology office, and results are often available in 4 to 10 days. If performed incorrectly, and without appropriate clinical information, the interpretation of a skin biopsy can be severely limited. There are four main types of skin biopsies: shave biopsy, punch biopsy, excisional biopsy, and incisional biopsy. The choice of the different skin biopsies is dependent on the suspected diagnosis of the skin lesion. It is often not known that you do NOT have to have a lesion cut out with stitches to diagnose it. Also, it is very infrequently that you would require sedation, nearly all biopsies can be done in an office setting with local numbing medication.

Shave biopsy

This is done with either a small scalpel blade, a curved razor blade, or a broken piece of “safety” razor. Ideally, the razor will shave only a small fragment of protruding tumor and leaving the skin relatively flat after the procedure. Any bleeding is then stopped using chemicals or cautery devices.

Punch biopsy

This is done with a round shaped knife (similar to a cookie cutter) ranging in size from 1mm to 8 mm. The common punch size used to diagnose most inflammatory skin conditions is the 3 or 4 mm punch. Ideally, the punch biopsy includes the full thickness skin and subcutaneous fat in the diagnosis of skin disease.

Incisional biopsy

A cut is made through the entire skin down to the subcutanous fat. A punch biopsy is essentially an incisional biopsy, except it is round rather than elliptical since most incisional biopsies done with a scalpel. Incisional biopsies can include the whole lesion (excisional), part of a lesion, or part of the affected skin plus part of the normal skin (to show the interface between normal and abnormal skin).

Excisional biopsy

This is essentially the same as incisional biopsy, except the entire lesion or tumor is included. The excisional biopsy is often done with a narrow surgical margin.