Simultaneous merkel cell carcinoma and acute myeloid leukaemia: A diagnostic challenge.

Merkel cell carcinoma is a very aggressive primary skin tumour with a high risk of local recurrences and lymphatic and distant metastases. The frequent association between this carcinoma and other skin tumour and lymphoid malignancies, its similar cellular morphology with leukocytes, and limited infiltration in bone marrow constituted a challenging diagnosis. We report an unusual case of an 82-year-old male who simultaneously presented Merkel cell carcinoma and acute myeloid lymphoma. The diagnosis was established through flow cytometry, immunohistochemical studies and next generation sequencing (NGS) analysis. Flow cytometry allowed for the differentiation of the two cell populations in bone marrow aspirate, which was crucial to the diagnosis of Merkel cell carcinoma and acute myeloid leukaemia (AML), after confirmed by immunohistochemistry. AML could be classified based on NGS results. Following diagnosis, the patient received palliative care and died 50 days later. immunophenotypic analysis by flow cytometry and Immunohistochemical study was crucial to establish the diagnosis of simultaneous affection of Merkel cell carcinoma and hematologic disorder.