Sequential development of diffuse panbronchiolitis and myasthenia gravis after thymectomy for thymic neoplasm: a case report

Abstract

Abstract Background Myasthenia gravis (MG) is the most common paraneoplastic disorder associated with thymic neoplasms. MG can develop after thymectomy, and this condition is referred to post-thymectomy myasthenia gravis (PTMG). Diffuse panbronchiolitis (DPB), is a rare form of bronchiolitis and is largely restricted to East Asia, has been reported in association with thymic neoplasms. To our knowledge, only three cases of combined MG and DPB have been reported. Case presentation: A 45-year-old Taiwanese woman presented to our hospital with productive cough, rhinorrhea, anosmia, ear fullness, shortness of breath, and weight loss. The patient had a history of thymoma, and she underwent thymectomy with adjuvant radiotherapy 7 years ago. Physical examination revealed coarse breathing sounds with inspiratory crackles. Chest computed tomography scan revealed progressive diffuse bronchitis and bronchiolitis. DPB was confirmed on video-assisted thoracoscopic surgery lung biopsy, and sputum culture showed the presence of Pseudomonas aeruginosa. The patient’s respiratory symptoms improved after treatment with oral azithromycin, levofloxacin, and the transient use of inhaled amikacin. Three months after DPB diagnosis, she developed ptosis, muscle weakness, and hypercapnia, with an arterial partial pressure of carbon dioxide measuring 78.6 mmHg, requiring the use of noninvasive positive pressure ventilation. MG was diagnosed based on the acetylcholine receptor antibody and repetitive stimulation test results. Muscle weakness responded to pyridostigmine and corticosteroids. However, she was readmitted after several months because of another episode of P. aeruginosa-related respiratory infection. Currently, she is in stable condition with long-term maintenance therapies comprising pyridostigmine, corticosteroid, azithromycin, and inhaled amikacin. Conclusions To best of our knowledge, this might be the first case of sequential development of DPB followed by PTMG. The coexistence of DPB and PTMG poses a therapeutic challenge for balancing infection control for DPB and immunosuppressant therapy for MG.