Thymoma is associated with:
Approximately 75% of the patients with myasthenia gravis may have thymic abnormalities. About 30% of the patients with myasthenia gravis have thymoma. So Myasthenia gravis is the single best answer of choice. Ref: Harrison's Principles of Internal Medicine, 16th Edition, Page 2521
Myasthenia gravis
Hypergammaglobulinemia
SLE
Multiple sclerosis