13-year survival oligometastatic Merkel cell carcinoma: a case report

Merkel cell carcinomas are rare, aggressive skin tumors with high metastatic potential and poor prognosis. Their treatment is classically based on surgery with adjuvant external radiotherapy for localized tumors or on immunotherapy or chemotherapy, sometimes associated with radiotherapy, for metastatic stages. Those tumors are highly radiosensitive due to their neuroendocrine and undifferentiated nature, but they usually fail to rapidly respond to treatment.

We report the case of a 65-year-old retired female patient of Caucasian (German) origin with locally advanced Merkel cell carcinoma of the buttock, with pancreatic metastases synchronous at diagnosis, treated with local radiotherapy of the right buttock without regional lymph node irradiation followed by a sequential chemotherapy; 1 year later, the patient developed an isolated pancreatic recurrence treated with exclusive radiotherapy. The patient was still alive at 13 years with complete remission.

External radiotherapy can be an effective alternative to surgery for locally advanced or even oligometastatic Merkel cell carcinomas.