Myasthenia gravis

In practice, myasthenia gravis is mainly an “imaging the thymus” disease.

Common

• Thymic follicular hyperplasia / Thymic hyperplasia (often diffuse, symmetric; can show chemical-shift signal drop)
• Thymoma (anterior mediastinal mass; classic association)

Uncommon

• Thymolipoma: Fat-containing thymic tumour

Exam trap

• Small cell lung cancer is classically linked to Lambert-Eaton, not MG (different NMJ problem, easy to mix up).
• Thymic carcinoma (MG association is very rare, largely case reports; don’t treat it as a typical pairing)