Concurrent Hairy Cell Leukemia and Metastatic MerkelCell Carcinoma

Hairy cell leukemia (HCL) and Merkel cell carcinoma (MCC) are two rare malignancies with distinct cells of origin. HCL is alymphoid malignancy of mature B cells, and MCC derives from neuroendocrine cell origin. HCL has a favorable prognosis withmost patients achieving long-term remission and potential cure. In contrast, MCC is an aggressive malignancy affecting the skinand can metastasize quickly with a dismal prognosis. Immunocompromised patients, such as those with AIDS, posttransplant,and the elderly, have higher incidences than the general population, suggesting a possible immune mechanism. We reporta case where a patient presented with HCL and metastatic MCC synchronously. This is thefirst reported case of thesetwo rare malignancies occurring concurrently at initial presentation and may represent a role of immunosuppression in thepathogenesis of MCC