A 40-year-old woman presents with myasthenia gravis (generalized, anti-AChR positive). She fails pyridostigmine and prednisolone and requires multiple PLEX cycles. Thymectomy is planned. Which finding on CT chest would provide the STRONGEST indication for thymectomy?
- A Thymoma (encapsulated, Masaoka Stage II) ✓
- B Normal thymus on CT
- C Thymic hyperplasia only
- D Thymolipoma
Explanation
The MGTX trial established thymectomy as beneficial even in non-thymomatous MG (improved 3-year outcomes vs. prednisone alone). However, the absolute mandatory indication for thymectomy is the presence of thymoma, as thymoma carries risk of local invasion and metastasis regardless of MG status—all patients with thymoma and MG require surgical resection. Encapsulated Masaoka Stage II thymoma (minimal capsular invasion) still requires complete resection. Thymic hyperplasia benefits from thymectomy but is not as urgent as thymoma. Thymolipoma is a benign fatty tumor that rarely causes MG.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.