Postallograft aleukemic mast cell leukemia, with macrophagic activation syndrome

[摘要] A 60-year-old male suffering from hypertension and a treatedmyelodysplastic syndrome (MDS-EB2) by an allograft 3 years beforethe current presentation was presented with a deteriorating generalcondition and asthenia. A blood work-up was done where hypereosinophilia (24 × 103/µl) was incidentally found, hardly attributableto a postallogeneic peripheral blood stem cell transplantation [2].Thepatient was then referred to our hematology department for furtherinvestigation. Upon admission, a myelogram revealed 7% of mastocytes, often in aggregates, some showing atypical forms (hypogranulation, spindle-shape, and hypersegmentation of nucleus) (Figure 1A,B),and 51% of eosinophilic lineage. Flow cytometry (FC) showed 7% ofmast cells with CD2 and CD25 aberrant expression. No genetic abnormalities including typical c-KIT mutation were shown by NGS (wholeexome) and PCR (only mutation c.2447A>T (p.D816V)). Fluorescencein situ hybridization (FISH) technique showed no translocation involving FIP1L1, PDGFRA, or PDGFRB. Molecular chimerism was completewith a sensitivity threshold of 5%. With major criteria, the diagnosis of systemic mastocytosis with eosinophilia was retained. This diagnosis was supported by hepatosplenomegaly and signs of symmetrical medullary recruitment in the long bones. Given the patient’s initialdiagnosis, serum tryptase (higher than 20 ng/ml) could not be used as avalid minor criterion [1, 3].