Merkel cell carcinoma in organ transplant recipients: Case reports and review of the literature.

MCC: Merkel cell carcinoma OTRs: organ transplant recipients INTRODUCTION Merkel cell carcinoma (MCC) is an aggressive tumor of the skin and mucous membranes that typically occurs in elderly white men and in immunosuppressed individuals. The reported incidence of MCC has tripled over the last 20 years in the United States from 0.15 to 0.44 cases per 100 000 between 1986 and 2001. In light of the poor prognosis and high risk for recurrence, metastasis, and death associated with MCC, this increasing trend is of concern. The risk factors for MCC are similar to those for other skin cancers, mainly ultraviolet light exposure, older age, T-cell immunosuppression, fair skin, and male sex. Although a rare tumor, MCC is seen more frequently in the immunosuppressed population, and immunosuppressed MCC patients tend to be younger at diagnosis and have less favorable disease outcomes. Specifically, HIV positivity, lymphocytic leukemia, and iatrogenic immunosuppression after organ transplantation confer an increased risk of MCC. Here we report 2 cases of MCC occurring in organ transplant recipients (OTRs), illustrating how iatrogenic immunosuppression in the setting of organ transplantation can impact tumor progression and potentially decrease survival. We summarize current evidence regarding the pathogenesis, staging, and treatment of MCC and bring forth our recommendation to monitor high-risk OTR with frequent skin examinations. MCC has a poor prognosis and its management remains a challenge. Early recognition can improve clinical outcomes and disease-specific and overall survival in the transplant population.