Abstract
In this study, the authors analyzed the prognostic value of four clinical variables[age and sex of patients, association with myasthenia gravis and clinical stage] and histological type in 30 consecutive patients with thymoma, histologically classified as cortical[10],medullary[5] and mixed[15]type according to Marino and Muller-Hermelink classification. There were significant differences between the histological types in the frequency of the different tumor stages and myasthenia gravis and prognosis.Most of the cortical thymomas were at stage III and all of the medullary and most of the mixed tumors at stage I or II.Myasthenia gravis occurred more commonly in patients with cortical[30%] and mixed thymoma[60%] than in patients with medullary thymoma[10%]. Follow-up was conducted in 30 patients,with follow-up range from 3 months to 120 months[mean,47.3months]. 5 year actuarial survival was 100% for medullary thymoma, 73% for mixed thymoma, and 47% for cortical thymoma.The overall survival curve shows that 87.6% of the patients are alive at 2 years and 72.8% at 5 years. And 7 patients was dead during follow-up periods.By Kaplan-Meier technique, we found that the patients who had myasthenia gravis had better prognosis[P<0.05]. Medullary thymoma is a comparatively rare, benign tumor, and usually not associated with myasthenia gravis. Cortical thymoma must be regarded as malignant. Mixed thymoma is intermediate in its behavior between medullary and cortical thymoma. But these tumors should be considered potentially malignant despite of presence as stage I of II disease. Also, the patients with stageI,II had good prognosis and the patients with total resection had good prognosis[P<0.05].
