Thymomas are rare neoplasms that can be benign or malignant. In one third to one half of cases, thymomas are associated with myasthenia gravis as an initial presentation (as in this case). Benign thymomas have a mixed population of lymphocytes and epithelial cells and are circumscribed, whereas malignant thymomas are invasive and have atypical cells. Thymic carcinomas resemble squamous cell carcinomas. Granulomas can have epithelioid macrophages and lymphocytes, but the thymus is an unusual location for them. Hodgkin lymphoma involves lymph nodes in the middle or posterior mediastinum, with a component of Reed-Sternberg cells. Lymphoblastic lymphoma of the T-cell variety is seen in the mediastinal region, including thymus, in children, but it has no epithelial component. Metastases to the thymus are quite unusual. An organizing abscess could have granulation tissue at its edge, with a mixture of inflammatory cell types, but not atypical cells.