Merkel cell carcinoma: review of 22 cases with surgical, pathologic, and therapeutic considerations.

BACKGROUND. Merkel cell carcinoma is a primary small blue cell tumor of the skin with a proclivity to metastasize, Surgery and radiation therapy have defined roles in the primary treatment of Merkel cell carcinoma. Systemic chemotherapy can produce good response rates but does not have a primary role in the management of nondisseminated Merkel cell carcinoma patients. METHODS. Twenty-two patients were identified over the last 10 years in a retrospective analysis of tumor registries from the 6 hospitals of the ScrippsHealth facilities. Hospital and clinic charts as well as pathology specimens were reviewed. RESULTS. Eight patients underwent Mohs' surgery with permanent tissue technique. None of these patients had a subsequent local recurrence. Six patients received adjuvant radiation therapy, only one of whom developed a disease recurrence within a radiation port. Systemic chemotherapy was given to seven patients. One patient did not accept further treatment after a punch biopsy. CONCLUSIONS. Merkel cell carcinoma is an aggressive primary neoplasm of the skin, the histologic diagnosis of which can be difficult. Mohs' surgical technique combined with radiation therapy provides excellent local control. Systemic treatment is associated with high response rates, but to the authors' knowledge durable responses are uncommon.