Systemic mastocytosis (SM) comprises a heterogeneous group of rare acquired and chronic hematological malignancies that are related to an abnormal proliferation of mast cells in tissue, including bone marrow, with or without skin involvement. The disease is systemic mastocytosis (MONDO_0016586, a Monarch Disease Ontology id). Also known as: SMCD - systemic mast cell disease, systemic tissue Mast cell disease, systemic tissue mast cell disease.