NCIt definition : A usually localized tumor composed of sheets of mast cells without atypia. It includes
the cutaneous mastocytoma which involves the dermis and subcutaneous tissue, and the
extracutaneous mastocytoma. Most cases of extracutaneous mastocytoma have been reported
in the lung.;
Alternative definition : NCI-GLOSS: A growth or lump of mast cells (a type of white blood cell). Mast cell
tumors can involve the skin, subcutaneous tissue, and muscle tissue.; CDISC: A benign neoplasm composed of mast cells.;