Merkel cell carcinoma after liver transplantation: a case report and review of the literature.

Merkel cell carcinoma is a rare type of highly aggressive cutaneous malignant neuroendocrine tumor. The incidence of Merkel cell carcinomas is higher in organ transplant recipients than healthy controls. There are some reports of Merkel cell carcinomas after kidney transplantation, but few reports of Merkel cell carcinomas after liver transplantation are available. We present a 64-year-old Chinese woman with an asymptomatic nodule on her right tibia 6 years after liver transplantation. The nodule appeared as a purulent scab on the surface and measured 2.4×2.5 cm in diameter. Histopathologic and immunohistochemistry examinations confirmed the nodule to be a Merkel cell carcinoma. No residual Merkel cell carcinoma was detected at the surgical margins after surgical resection. No metastases were detected in a sentinel lymph node biopsy specimen. The wound was suctioned with negative pressure. The patient had an uneventful recovery and was discharged 16 days after surgery. Then, she underwent postsurgical adjuvant radiotherapy. No relapse was observed for approximately 24 months of follow-up. Merkel cell carcinoma may severely impact health, especially among transplant recipients. Immunosuppressants that must be administered after transplantation can increase the risk of Merkel cell carcinoma and physicians should be aware of Merkel cell carcinomas occurring in liver transplant recipients.