33904 Early onset Merkel cell carcinoma in patients with XMEN disease

Abstract

Background: Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer frequently caused by Merkel cell polyomavirus (MCPyV). The median age for MCC diagnosis is 75 years, and MCC is vanishingly rare in patients under 40. We describe 3 patients with X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia (XMEN) who developed MCC before age 25. XMEN disease is a rare immunodeficiency associated with lymphoma and caused by mutations in the magnesium transporter 1 (MAGT1) gene. Methods: Retrospective chart review for 3 individuals with MCC and XMEN disease. Results: Patient 1 had a history of recurrent childhood infections and splenomegaly and presented at 14 years of age with metastatic MCC that was treated with high-intensity chemotherapy, radiation therapy, and an autologous stem cell transplant. Patient 2 had a history of chronic EBV viremia and recurrent infections and presented at age 22 with Stage III MCC that was treated with surgical resection and radiotherapy. Patient 3 had a history of thrombocytopenia, splenomegaly, and recurrent infections and developed Stage I MCC at age 24 that was treated with surgical resection and radiotherapy. All three patients had MCPyV positive tumors. The patients are alive and tumor-free 13, 4, and 9 years after diagnosis, respectively. Conclusion: Although immunosuppression increases MCC incidence, XMEN disease is associated with a risk for early onset MCC not observed in other primary immunodeficiencies. The MCPyV positivity and prolonged survival in these 3 cases is also atypical for immunosuppressed patients with MCC.