Thymic tumours associated with Myasthenia gravis: A long term observation study of operated patients

Abstract

Primary tumours of thymus, thymoma and thymic carcinoma, are very rare, they represent less than 1 % of all neoplasms. The most common manifestation of thymoma with appearance of 40 to 50 % of the neuromuscular autoimmune disease is myasthenia gravis (MG). The performance of acomplete resection is the most predictive indicator for long-term survival of patients with thymic tumour, also important prognostic factors are the histological type of thymic tumour and its invasiveness. The aim of our study is to study the long-term survival of patients after the resection of the tumour, as well as enhanced efficiency of radical thymectomy in the complex treatment of myasthenia gravis. From 1989 to 2010 we operated on 369 patients with MG. Out of 49 patients (13.7 %) 38 cases (76.6 %) were thymomas and 11 cases (23.4 %) thymic carcinomas. Complete removal of tumours (stage I, II, and III) were performed in 45 (92 %) cases. Of the41 living patients (83.7 %), three (7.3 %) were diagnosed with metastatic thymic carcinoma or thymoma, and treated with adjuvant therapy. In one case, the patient died due to generalization of the thymic carcinoma. Statistical analysis with Kaplan- Meier method showed better overall survival of patients with thymoma than patients with thymic carcinoma. The difference in survival curves was not significant. (Mantel-Cox p = 0.479, Generalized Wilcoxon p = 0.326). In terms of treatment of Myasthenia gravis associated with thymoma, we achieved 70 % successfulclinical and pharmacological remission. On the other hand, paraneoplastic MGAT has the worst prognosis of all the other forms of MG. The difference between MGAT to every other form of MG wasstatistically significant.