Definition

A rare condition in which too many mast cells (a type of white blood cell) build up in certain tissues and organs in the body, including the bone marrow, lymph nodes, bone, liver, spleen, and small intestine, and may damage them. In systemic mastocytosis with associated hematologic neoplasm, this mast cell buildup occurs together with another blood disorder, usually a myelodysplastic syndrome, myeloproliferative disorder, or acute myeloid leukemia (AML). Systemic mastocytosis with associated hematologic neoplasm usually occurs in adults. Also called SM-AHN.