WHAT IS THE PURPOSE OF A NAIL BIOPSY?
Very rarely, skin cancers can occur in the nail unit. In order to diagnose this, it is often necessary to biopsy the nail matrix or nail bed depending on the clinical situation. The most common reason for a nail biopsy is the evaluation of a black vertical line, (melanonychia), that spans the proximal to distal nail plate. Although most likely this could be a benign mole, only a biopsy can rule out a melanoma. The majority of nevi and melanoma that produce melanonychia reside in the nail matrix. Thus, it is essential to obtain tissue from the origin of the melanonychia in the nail matrix.
HOW IS A NAIL BIOPSY PERFORMED?
At Castle Dermatology, we routinely perform nail biopsies to rule out melanoma. We first perform a nerve block of the distal finger by placing a small amout of lidocaine into the medial and lateral aspects of the finger. A nail elevator is then used to detach a small portion of the cuticle from the nail bed and is reflected off the nail matrix. This exposes the biopsy site which is removed as a small ellipse. The cuticle is sutured in place and a bandage is placed on the finger. It is critical that the patient understand the nail plate may not grow back or be permanently distorted as the biopsy of the matrix can cause permanent damage to the nail. Occasionally, the nail bed must be biopsied as squamous cell cancers can arise in this area. This biopsy is performed similar to a nail matrix biopsy but without having to reflect the cuticle.