LAUSR

and bone marrow mast cell burden (Table 1). Next, we focused on SM-AHN-myeloid (n = 178), which included 11 (6%) patients with SM associated with acute myeloid leukemia (SM-AML), 50 (28%) patients with SM associated with myeloproliferative neoplasms (SM-MPN), 24 (13%) patients with SM associated with myelodysplastic syndromes (SM-MDS), 39 (22%) patients with SM associated with chronic myelomonocytic leukemia (SM-CMML) and 54 (30%) patients with SM associated with MDS/MPN/unclassified (SM-MDS/MPN/Unclassified). Figure 1C confirms the survival superiority of SM-AHN-lymphoid, compared to any other specific category of SM-AHN-myeloid. Prognostic comparison in SM-AHN-myeloid (Figure 1C) is confounded by significant variation in age and risk distribution of the specific myeloid components but appears to favor SMMPN and SM-MDS over other subcategories, including SM-CMML and SM-MDS/MPN/Unclassified (Figure 1C). We conclude that patients with SM-AHN-lymphoid are phenotypically and prognostically different than those with SM-AHN-myeloid and should be cited as such in both clinical practice and future survival studies in SM. Similarly, prognosis in SM-AHN-myeloid appears to be dictated by the specific AHN component, which underscores the need to be more specific in diagnostic assignment and treatment directions. This is particularly important since sensitivity to drug therapy or to other treatment modalities in SM might be different for neoplastic mast cells vs the associated myeloid neoplasm clone.