Essential Thrombocythemia Associated with Plasma Cell Neoplasm

Abstract

Abstract Introduction/Objective The co-occurrence of essential thrombocythemia (ET) and multiple myeloma (MM), two distinct entities with distinct cellular origin, is rare, with a limited number of cases reported. Methods/Case Report We report a case of a 63-year-old male who initially presented with thrombocytosis, splenomegaly and elevated LDH. A bone marrow examination showed hypercellularity (90%) with increased abnormal megakaryocytes, as well as a JAK2 V617F mutation, with overall features consistent with involvement by a myeloproliferative neoplasm (MPN), consistent with ET (versus early primary myelofibrosis (PMF)). Additionally, 6% kappa-restricted plasma cells were identified, consistent with involvement by a monoclonal gammopathy of undetermined significance (MGUS). The patient was subsequently treated with hydroxyurea. Four years later, he presented with evidence of paraproteinemia. IgG kappa monoclonal paraprotein was elevated at 3.4 g/dL. A repeat bone marrow examination showed hyper-cellularity (60%), including clusters of abnormal megakaryocytes and mild to moderate reticulin fibrosis. The previously identified kappa-restricted plasma cell population increased to approximately 40% of the total cellularity. Cytogenetic analysis showed a normal male karyotype (46,XY[20]), and a prognostic myeloma-FISH panel including 13q-/-13, 1q32/1q21, p53/NF1, CCND1/IgH t(11;14), FGFR3/IgH t(4;14), IgH/MAF t(14;16) and IgH/MAFB t(14;20) was negative for all tested abnormalities. The overall features were again consistent with involvement by an MPN and progression of the previously identified MGUS. Results (if a Case Study enter NA) NA. Conclusion Only a few cases of concurrent ET and MM have been previously reported in the literature, with most of these cases having a temporal association with alkylating agent therapy. However, MM development has also been reported in a patient with non-cytotoxic treatment of ET. In contrast, our patient was diagnosed with ET associated with MGUS at the initial diagnosis. Notably, the co-existence of early PMF with MM appears to be relatively more established. A large study showed that previous PMF was strongly associated with MM development (OR 24.3; 95% CI:2.9-201.5).