Merkel cell carcinoma of the skin and mucosa: Report of 12 cutaneous caseswith 2 cases arising from the nasal mucosa

BACKGROUND. Merkel cell carcinoma (MCC) is an uncommon skin tumor that most frequently arises on sun-exposed facial sites. It rarely occurs on mucous membranes of the head region. The primary MCC is usually treated by wide ex cision followed by radiation to the primary site and regional lymph nodes. Using traditional surgery the local recurrence rate ranges from 20 to 50%. In our clinic, Mohs surgery is used to excise the primary MCC completely, f ollowed by radiation. Here we present our treatment experiences and outcome s. OBJECTIVE. To document our experience of MCC treated by Mobs surgery. We pr esent our series of 12 cases of MCC, 2 cases of which arose from mucosal si tes of the nasal cavity. METHODS. We reviewed 12 cases of MCC from the Mohs clinic database. We also reviewed the literature for cutaneous and mucosal MCC. RESULTS. There were 12 cases of MCC: 10 cutaneous and 2 mucous. The site di stribution of cutaneous MCC was eight on the head, one on the neck, and one on the groin. Of these, nine were treated by Mohs excision. Two patients d eveloped local recurrence following Mohs treatment. The local recurrence ra te was 22% (2 of 9). The sites of mucosal MCC were the nasal septum and nas opharynx. One case had a history of previous radiation and developed an MCC 40 years later. This case also demonstrated epidermotropic spread of Merke l cells to the overlying mucous epithelium. This patient required extensive intranasal and cranial surgery to remove the tumor. Both patients with muc osal MCCs died of their disease. The overall mucocutaneous survival of MCC at 1 year was 80% and at 2 years was 50%. CONCLUSION. In our series, local control of the primary MCC was achieved in 70% of patients (7 of 10) using combined Mohs excision and radiation. Two recurrences had primary tumors larger than 3.5 cm in diameter, while the ot her case was nonresectable by Mohs surgery. Tumor size appeared to determin e the degree of local control. When the postoperative Mohs defect was less than 3.0 cm in diameter, local and regional control appeared to be more fav orable. When the primary facial MCC is relatively small, removal by Mohs su rgery followed by radiation was effective, therapeutic, and less disfigurin g. Mucosal MCC is rare and may occur as a long-term sequelae after radiatio n therapy to the skin.