Indolent systemic mastocytosis associated with multiple myeloma: A rare coexistence

Systemic mastocytosis (SM) includes a wide spectrum of clonal disorders characterized by an abnormal growth and accumulation of mast cells. SM may be associated with other hematological neoplasms (SM-AHN) among them the myeloproliferative neoplasms and myelodysplastic syndromes are the most common. The coexistence of SM with lymphoid malignancies has rarely been reported so far. The occurrence of SM associated with multiple myeloma (MM) is extremely rare and its prognosis remains unclear. The treatment of SM-AHM requires an individual approach. We report a male patient diagnosed with indolent SM associated with MM. He did not require the therapy for his SM, but started the treatment against MM. He received the induction regiment consisting of bortezomib, thalidomide and dexamethasone (VTD). After six cycles of VTD he achieved a very good partial response, but refused autologous stem cell transplantation as response consolidation and eventually died of myeloma progression a couple months later. Herein we discuss the likely pathophysiologic mechanisms underlying those two separate entities.