Primary thrombocythaemia associated with systemic mastocytosis: a report of five cases.

Mastocytosis is an uncommon disease characterized by a proliferation of tissue mast cells involving various organs, particularly the bone marrow. Though rare, the association of mastocytosis and haematological malignancies is well established. However, the frequency of mastocytosis reported in patients with essential thrombocythaemia is relatively low. We report five cases of such an association. Our five patients were undergoing evaluation for thrombocyte when the bone marrow biopsy revealed the presence of mastocytosis. The pathogenetic significance of this association is poorly understood. The different hypotheses are discussed.