Thymoma Type AB

**Semantic type:** Neoplastic Process

**Definition:** A thymic epithelial neoplasm characterized by the presence of a lymphocyte-poor component similar to that seen in type A thymoma and a lymphocyte-rich component which contains neoplastic small polygonal epithelial cells. It may be associated with myasthenia gravis and pure red cell aplasia. The majority of cases occur in the anterior mediastinum as Masaoka stage I tumors. A minority of the cases occur as stage II or stage III tumors. The overall survival is reported to be 80-100% at 5 and 10 years.

**Synonyms:** - Mixed Type Thymoma - Thymoma, type AB, NOS