Systemic mastocytosis associated with essential thrombocythemia.

Mastocytosis comprises a spectrum of disorders characterized by abnormal growth of mast cells (MS). Four entities are recognizable according to WHO classification. Association of systemic mastocytosis (SM) with a chronic myeloproliferative neoplasia (SM-AHNMD) is the second frequently category. Published descriptions of the clinicopathologic features of SM-AHNMD are largely limited to individual case reports. We present the case of a 41-year-old woman with thrombocytosis and mild splenomegaly. Clinical suspicion was of chronic myeloproliferative neoplasia (CMN). Bone marrow trephine biopsy examination (histology and immunohistochemistry for CD117 and CD25) revealed a SM associated with CMN, essential thrombocythemia (ET) type. The JAK2 V617F (for CMN) was detected but KIT/Asp816Val (reported in ~80% of SM) was absent. We discussed the particularity of the cases correlated with a review of the literature.