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 SM-AHN, this mast cell buildup occurs together with another blood disorder, usually a myelodysplastic syndrome, myeloproliferative disorder, or acute myeloid leukemia (AML). SM-AHN usually occurs in adults. Also called systemic mastocytosis with associated hematologic neoplasm.