Mast cell leukemia is extremely rare, more often arises de novo and in 15% of cases developes from preexistence mast cell diseases. It is a high malignant leukemia with bad prognosis and a short survival. A 72-year old female was admitted to hospital with clinically suspected plasmocytoma. She had eccematoid changes on her trunk and underarms. Radiogramm showed osteolytic lesions of the right thigh and pelvis. FNA of the bone marrow revealed hypercellular smear with 80% of mast cells and immature mast cells which were cytochemically positive to toluidin (Figure 1. and 2.), chloracetate, alcian blue, acid fosphatase and Sudan black and negative to periodic acid Schiff (PAS) and peroxidase (POX). The peripheral blood smear showed single mast cells which were positive to toluidin. The bone marrow biopsy confirmed mast cell leukemia. The chariogramm of the bone marrow showed numerical and structural chromosomal changes. Two month after the diagnosis the patient suffered from right thigh fracture and was treated with local radiotherapy, antihistaminic and analgetic therapy. The patient died within 6 month after the diagnosis.
Conclusion: Mast cell leukemia is very rare and high grade leukemia with short survival time. Cytological diagnosis is possible, when there is more then 20% of atypical mast cells in the bone marrow aspirate. The diagnosis of aleukemic variant of mast cell leukemia could be stated if there is less then 10% of mast cells in the peripheral blood.