The management of pigmented lesions of the nail bed

Pigmented lesions of the nail bed, especially without a history of trauma, represent a diagnostic challenge to the clinician. These lesions are often categorized as melanonychia striata (MS), which refers to any linear tan-brown-black pigmentation of the nail bed. The differential diagnosis of MS includes subungual hematomas, onchomycosis nigricans, junctional nevi, melanoma in situ (MIS), and malignant melanoma (MM). Our algorithm at the New York University (NYU) Medical Center for the treatment of pigmented lesions of the nail bed is presented. A histopathologic diagnosis with any evidence of melanocytic atypia, however subtle, requires absolute confirmation by complete excision. The absence of a clear margin or recurrence requires total nail bed excision and reconstruction using a full-thickness graft. The diagnosis of MIS is similarly treated. The surgical management of subungual MM is discussed. All cases of MM of the hand treated at NYU were reviewed. In all, 30 patients were treated from 1982 to 1995. Follow-up ranged from 6 months to 13 years. In our series, there were 8 cutaneous and 22 subungual melanomas. There was a marked delay in treatment of both groups, with subungual melanomas more often erroneously treated as other pathology prior to correct diagnosis. The 5-year survival rate was 100% for patients with cutaneous lesions, but only 80% for those with the subungual variety. There was a statistical difference in the depths of the lesions (subungual, 3.68 mm; cutaneous, 1.36 mm) with a p-value of 0.008. The role of elective lymph node dissection in the absence of clinical metastases as well as intraoperative sentinel lymphatic mapping remains controversial and is discussed.