Abstract

We report a case of systemic mastocytosis associated with a clonal hematological non-mast-cell lineage disease (SM-AHNMD) where the associated disease is acute erythroid leukemia (erythroid/myeloid type). Interestingly, molecular studies showed the KIT^D816V+ mutation not only in the mast cells, but also, in the myeloid blast population and the leukemic erythroid cells. As is the case with most erythroid leukemias, the patient had a very aggressive clinical course and died shortly after diagnosis. To the best of our knowledge, this is the first reported case of systemic mastocytosis with erythroid leukemia where the KIT^D816V+ mutation was detected in all three cell types. Our molecular findings provide evidence for derivation of these seemingly morphologically distinct lesions from the same clonal precursor cell. From a practice standpoint, this case illustrates the importance of definitively diagnosing the associated non mast-cell-lineage disease due to its prognostic implications.