types
Last reviewed 01/2018
Thymomas display a spectrum of neoplastic behaviours. Three main types are recognised:
- benign - the most common, accounting for 80-90% of thymomas. Characterized by a diffuse proliferation of neoplastic thymic epithelial cells and an abundance of lymphocytes. There is no capsular invasion.
- malignant type I - cytologic features are identical to the benign thymoma but with additional invasion of the capsule. Occasionally, there may be metastases to the lungs and bone.
- malignant type II - known as thymic carcinoma. There is capsular invasion and cytologic pleomorphism. The tumour often resembles a squamous cell carcinoma.