Systemic Mastocytosis Associated with Smoldering Multiple Myeloma

A 79-year-old woman presented with a long history of peripheral eosinophilia. Previous right hemicolectomy for colonic polyposis was reported. Laboratory tests were notable for mild macrocitic anaemia and eosinophilia. beta 2 microglobulin and serum tryptase levels were elevated. Serum immunofixation revealed IgA/kappa monoclonal protein. Bence-Jones protein was positive. Bone marrow (BM) biopsy revealed the coexistence of two neoplastic components. Cohesive clusters of bland-looking, spindle-shaped mast cells, representing 20% of marrow cellularity, were close to aggregates of mature plasma cells occupying 40% of marrow cellularity. Molecular analysis on marrow aspirate demonstrated KIT D816V mutation, TET2 mutation, monoallelic deletion of TP53/17p13 and trisomy of ATM/11q23. A bone density study revealed mild osteoporosis. Full skeletal X-rays and magnetic resonance imaging (MRI) of spine and hips showed multiple, small rarefaction areas and an old L1-L2 fracture, both ascribed to osteoporosis. The association of systemic mastocytosis (SM) and multiple myeloma (MM) is very uncommon. The coexistence of SM with MM placed our patient in the SM with associated clonal haematological non-mast-cell lineage disease (SM-AHN) subtype. Midostaurin therapy was started.

Automated summary

A 79-year-old woman presented with peripheral eosinophilia, with a history of colonic polyposis and subsequent right hemicolectomy. Laboratory tests revealed mild macrocitic anaemia, elevated beta 2 microglobulin and serum tryptase levels, and the presence of IgA/kappa monoclonal protein and Bence-Jones protein. Bone marrow biopsy showed two neoplastic components - mast cells and plasma cells, with molecular analysis demonstrating mutations and chromosomal abnormalities. The rare coexistence of systemic mastocytosis and multiple myeloma led to treatment with midostaurin therapy.