Mastocytoma

**Semantic type:** Neoplastic Process

**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.

**Synonyms:** - Benign Mastocytoma - MAST CELL TUMOR, BENIGN - Mastocytoma, NOS - mastocytoma