Merkel cell carcinoma: an aggressive malignancy.

Merkel cell carcinoma is a rare and aggressive malignant tumor of the skin. We retrospectively reviewed five patients treated from January 1987 to December 1995. The mean age was 75 years (range, 65-85). There were three primary lesions of the head and neck and two of the extremities. Three were stage II and two were stage III. All primary tumors underwent wide excision with clear margins. Four patients recurred, with a mean time to recurrence of 10 months (range, 2-17). All tumors were positive for immunohistochemical stains (cytokeratin and neuron-specific enolase). Only the two patients who did not have radiotherapy to the primary site had a local recurrence. There was regional recurrence in two of the three patients who had adjuvant radiotherapy to regional lymph nodes. One patient who had a wide excision of the primary lesion, prophylactic lymph node dissection (15 of 34 lymph nodes were positive), and adjuvant chemotherapy is alive and disease free at 23 months. Three patients have died with disease, and two are alive and disease free. Merkel cell carcinoma should be treated aggressively with wide excision of the primary lesion (3-cm margins), and prophylactic lymphadenectomy followed by irradiation to the primary site. If lymph node involvement is detected, then irradiation to the lymph node region must be performed. The role of chemotherapy in this disease is not well defined.