Background: Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumor. Its incidence is markedly greater in immunocompromised patients. MCC is found almost exclusively on sun-exposed facial sites.
Case Report: We describe a case of a 62-year-old male renal transplant recipient who was diagnosed with MCC with primary atypical localization on the buttock 5 years after transplantation. Despite the conversion from CsA to mTOR inhibitor, surgical operation, and radiotherapy, the patient developed disseminated skin lesions and died due to multiple metastases.
Conclusions: This case emphasizes the importance of screening for MCC in atypical localizations in transplant organ recipients

Keywords: renal transplantation, merkel cell carcinoma, skin cancers, immunosuppressive therapy