If we are concerned that a lesion may be dangerous, we will often perform a skin biopsy. Another reason for skin biopsy is to diagnose certain types of rashes. This involves numbing the skin with an anesthetic such as lidocaine and surgical removing a piece of the lesion. The specimen is then sent to a dermatopathologist for microscopic evaluation to help aid in diagnosis. Skin biopsy may or may not require stitches.