Systemic mastocytosis (SM) consists of a group of disorders exhibiting excessive mast cell accumulation, typically in bone marrow and other extracutaneous tissues.
There are four distinct forms of SM (table 1):
●Indolent systemic mastocytosis (ISM)
●Systemic mastocytosis with an associated hematologic nonmast cell lineage disorder (SM-AHNMD)
●Aggressive systemic mastocytosis (ASM)