Tumors of the thymus

Thymic neoplasms are a common cause of an anterior mediastinal mass and may be benign or malignant. Thymic cysts are congenital or acquired and may be associated with a thymic malignancy. True thymic hyperplasia and thymic ly mphoid hyperplasia may enlarge the thymus and simulate a neoplasm. Thymoma and thymic carcinoma are epithelial malignancies with distinct clinicopatho logic features. Thymic carcinoid is a rare aggressive neuroendocrine malign ancy associated with multiple endocrine neoplasia 1. Thymolipoma is a benig n neoplasm. Hodgkin and non-Hodgkin lymphoma may primarily or secondarily i nvolve the thymus. Primary mediastinal germ cell tumors may arise primarily within the thymus and include mature teratoma, seminoma, and non-seminomat ous malignant germ cell tumors.