Merkel cell carcinoma in a patient treated with adalimumab: case report.

Merkel cell carcinoma (MCC) is a rare aggressive neuroendocrine tumor that manifests as an asymptomatic enlarging lesion often in the setting of immunosuppression, advanced age, or UV exposure. Immunosuppression has been associated with melanoma, lymphoma, and nonmelanoma skin cancer (NMSC). We present a case of a patient with a long-standing history of rheumatoid arthritis treated with adalimumab, methotrexate, and prednisone who developed a painless, rapidly enlarging lesion that was found to be MCC with lymph node involvement. As the use of tumor necrosis factor (TNF) alpha inhibitors becomes more popular, it is important to identify the potential long-term risks associated with chronic immune modulation. Systemic immunosuppression may be a risk factor for the development of advanced-stage MCC. Treatment with the TNF-alpha inhibitor adalimumab may enhance this risk.