[Polyneuropathy as a sole syndrome in malignant thymoma]

Up to 40% of patients with malignant thymoma suffer from paraneoplastic symptoms (90% myasthenia, 10% other symptoms). A 55-year-old patient developed ascending symmetrical sensorimotor tetraparesis. A malignant thymoma without metastases was diagnosed 6 months later. Despite thymectomy followed by radiation and high-dose corticosteroid therapy, the polyneuropathy progressed. Six months after onset, the patient was bound to a wheelchair. Immunosuppressive therapy with cyclophosphamide was initiated, leading to marked remission. After ten cycles, the patient was able to walk independently with walking aids. After the sixth and tenth cycle, respectively, attempts to discontinue immunosuppression led to relapse. In several diagnostic workups, however, there was no tumour relapse. After 13 cycles, cyclophosphamide was replaced by immunoglobulins (0.4 g/kg per day i.v. for 5 days/month) due to progressive renal failure. The patient died just before the second course of this treatment. In conclusion, in the differential diagnosis of rapidly progressive polyneuropathy, a malignant thymoma should be considered, even in the absence of myasthenia. Immunosuppression with cyclophosphamide resulted in amelioration of symptoms in this patient.