Description of a case: merkel cell carcinoma in a male nipple after a kidney and liver transplant

Primary Merkel cell carcinoma (MCC) is rare primary neuroendocrine skin carcinoma that arises most commonly on sun-damaged skin of elderly or immunosuppressed patients. Breast involvement is even rarer with incidence under 0.1% of all breast carcinomas. To our knowledge, only eight cases of primary MCC of the breast have been reported in the literature and seven of them were in female patients. We present the second case of primary MCC described in a male breast so far. A 61-year-old male presented for evaluation of a mass in the left nipple. He presented a double kidney and liver transplant in 2014 due to an hepatocarcinoma. The patient was definitively diagnosed as unresectable locally advanced MCC. MCC risk is sharply elevated after solid organ transplant, likely resulting from long-term immunosuppression. MCC should be suspected in the presence of a rapidly amelanotic growing mass in the breast.