mast cell neoplasm (Monarch Disease Ontology term MONDO_0002724) is a heterogeneous group of disorders characterized by the abnormal growth and accumulation of mast cells in one or more organ systems. Recent data suggest that most variants of mast cell neoplasms are clonal disorders. (WHO, 2001). Also known as: Mast cell proliferative disease, Mast cell tumor, Mast cell tumour, mast cell tumor, mast cell tumour, neoplasm of Mast cells, neoplasm of the Mast cells, tumor of Mast cells.