BACKGROUND. Merkel cell carcinoma (MCC) is a rare, aggressive, cutaneous neoplasm. The primary form of initial treatment is wide surgical excision. The use of Mohs micrographic surgery as the primary form of treatment in MCC has been controversial. The course of MCC is often aggressive, with early metastasis, widespread disease, and death. Despite the poor prognosis, spontaneous regression has occasionally been reported. OBJECTIVE. We describe the clinical course of two patients with Merkel cell carcinoma who underwent treatment with Mohs micrographic surgery for the primary MCC. Metastases were excised in the first case and spontaneously regressed in the second. Both patients are without clinical disease at the time of this report. METHODS. Histopathology, clinical records, and the current literature are reviewed. RESULTS. One patients was without recurrence of MCC for 13 years of follow- up. The other patient experienced clinical spontaneous remission after nodal spread of the disease, with no recurrence for 18 months after clinical remission and 24 months after surgery. CONCLUSION. The treatment of Merkel cell carcinoma with Mohs micrographic surgery (MMS) has been successful for the control of primary skin disease, and is at least comparable to wide excision. Spontaneous regression may occur in the course of this usually relentless and aggressive disease. The explanation for spontaneous regression of MCC is unknown.
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