Case report: blastic Mantle Cell Leukemia.

The patient, who was being followed up for Mantle Cell Lymphoma, was diagnosed with Mast Cell Leukemia 2 years after receiving R-CHOP treatment. The results of flow cytometry, which was performed upon determining leucocytosis and detecting blasts in the peripheral smear following the patient's presentation due to his poor general condition, was consistent with Mantle Cell Leukemia. This case is being presented since there are a very limited number of previously published cases on this topic.