August 3, 2010

Excisional biopsies are used almost exclusively for skin lesions suspected of being cancer, especially pigmented lesions worrisome for melanoma.  As most melanomas are under 6mm, a punch biopsy can be used to obtain an excisional biopsy.  Although punch biopsies exist that are 8mm and 1cm, I never use a punch biopsy over 6mm.  Punch biopsies create a circular defect and it is impossible to close a circular defect over 6mm as a straight line as the ends of the circle “pooch” forming a raised area called a Burow’s triangle.  Thus, an excisional biopsy is best employed for those lesions larger than 6mm.  The lesion is excised with a very small margin (1-2mm) so the entire lesion can be viewed by the dermatopathologist.  The depth of the biopsy extends to the subcutaneous tissue so it includes all three layers of the skin.  I prefer to close the defect with a layer of subcuticular/dermal sutures, which dissolve, followed by a layer of non-absorbable sutures that close the epidermis.