Nail unit squamous cell carcinoma: updates on diagnosis, surgical approach, and the use of mohs micrographic surgery.

Nail unit squamous cell carcinoma (NSCC) is a malignant neoplasm that can arise from any part of the nail unit including the nail bed, nail matrix, nail groove, and nail fold. Nail unit SCC is the most common malignant nail neoplasm, and yet its diagnosis often is delayed, partly due to the clinical presentation of NSCC mimicking benign conditions such as onychomycosis, warts, and paronychia. Nail unit SCC has a low rate of metastasis; however, a delayed diagnosis often can result in local destruction and bone invasion. It is imperative for dermatologists who are early in their training to recognize this entity and refer for treatment. Many approaches have been used to treat NSCC, including wide local excision, digital amputation, cryotherapy, topical modalities, and recently Mohs micrographic surgery (MMS).