Neoadjuvant chemotherapy enabling resection of stage IVA thymoma with myasthenia gravis and systemic lupus erythematosus: a case report

Background: Thymomas are rare epithelial tumors of the anterior mediastinum associated with autoimmune disease, particularly myasthenia gravis (MG). The coexistence of thymoma, MG, and systemic lupus erythematosus (SLE) is uncommon and can complicate diagnosis due to overlapping autoimmune manifestations. Management of advanced thymoma is challenging given limited prospective data and an uncertain optimal role for neoadjuvant therapy. Case presentation: A 32-year-old woman with systemic lupus erythematosus (SLE) presented with progressive proximal muscle weakness, diplopia, and dysphagia. Examination and serologic testing confirmed MG with elevated acetylcholine receptor antibodies. Chest computed tomography showed an anterior mediastinal mass (8.7 × 6.0 × 8.8 cm) abutting major mediastinal vessels, including the left superior pulmonary vein, main pulmonary artery trunk, left atrial appendage, and left brachiocephalic vein with concern for vascular invasion, along with pleural drop metastases. CT-guided core needle biopsy demonstrated thymoma, and the disease was staged as clinical stage IVA (cT2N0M1a). She received four cycles of cisplatin, doxorubicin, and cyclophosphamide (CAP) followed by two cycles of carboplatin and paclitaxel. Neoadjuvant therapy led to significant clinical improvement, near-complete resolution of dysphagia and weakness, marked radiographic tumor regression, and disappearance of pleural lesions. She subsequently underwent median sternotomy with extended thymectomy and en bloc resection of involved mediastinal tissues. Final pathology confirmed predominantly type B3 thymoma with negative margins. Postoperative radiotherapy was administered. At latest follow-up, she had complete resolution of MG symptoms and no radiographic evidence of recurrent disease. Conclusion: stage IVA thymoma with concurrent autoimmune disease and demonstrates that neoadjuvant chemotherapy can enable complete resection of advanced disease. Unlike our prior rheumatologic report on this patient, which focused on the SLE-MG coexistence, this report emphasizes multidisciplinary oncologic management of stage IVA thymoma, including neoadjuvant chemotherapy, surgical resection, adjuvant radiotherapy, and oncologic outcomes. Detailed reporting of such cases remains important to guide treatment strategies for advanced thymoma.