[Pubmed] Chemotherapy-induced myasthenia gravis presenting as isolated bulbar palsy in a patient with WHO type B3 thymom

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Medicine (Baltimore). 2026 Aug 14;105(33):e50223. doi: 10.1097/MD.0000000000050223.

ABSTRACT

RATIONALE: Myasthenic crisis rarely manifests exclusively as isolated bulbar palsy in patients with WHO type B3 thymoma undergoing neoadjuvant chemotherapy, often leading to misdiagnosis as chemotherapy toxicity or infection.

PATIENT CONCERNS: A 55-year-old man with an invasive anterior mediastinal mass developed progressive dysphagia and dysarthria 5 days after the first cycle of CAP (cyclophosphamide, doxorubicin, cisplatin) chemotherapy, raising concerns for acute neurological deterioration.

DIAGNOSES: Neurological examination localized to bulbar involvement. Elevated anti-acetylcholine receptor antibodies (1.03 nmol/L), a positive ice-pack test, and objective improvement with the neostigmine test confirmed a chemotherapy-induced myasthenic crisis. A core-needle biopsy had previously established a WHO type B3 thymoma diagnosis.

INTERVENTIONS: The patient was placed nil by mouth with nasogastric decompression and correction of cisplatin-associated hypomagnesemia. Immunomodulation included pulsed methylprednisolone, intravenous immunoglobulin, and oral pyridostigmine. After symptom resolution, he completed a second CAP cycle followed by R0 video-assisted thoracoscopic thymectomy and adjuvant radiotherapy (60 Gy).

OUTCOMES: Bulbar symptoms resolved completely within 4 days of immunomodulation. At 29 months of follow-up, neither local tumor recurrence nor myasthenia gravis relapse was observed, with excellent performance status.

LESSONS: Isolated bulbar palsy can be the sole inaugural sign of chemotherapy-triggered myasthenic crisis. Clinicians should rapidly screen for acetylcholine receptor antibodies in thymoma patients receiving cytotoxic therapy. Integrating baseline serological risk assessment before chemotherapy may prevent life-threatening delays in care.

PMID:42601737 | DOI:10.1097/MD.0000000000050223


Source: https://pubmed.ncbi.nlm.nih.gov/4260173 ... 3&v=2.20.1