Clinicopathological Features in Thymoma-Associated Autoimmune disease

Abstract

Objectives: The WHO classification of thymic epithelial neoplasms was published by Rosai et al. in 1999, leading to a tentative standardization. There have only been a few reports about the usefulness of the WHO classification for thymoma in patients with concomitant autoimmune disease. The prognosis of typical thymoma in patients with concurrent autoimmune diseases was assessed based on the WHO classification in the present study. Subjects : Of 100 patients with thymic epithelial neoplasms that were surgically removed at our department between October 1983 and February 2002, 97 were included in this study. The three excluded patients had thymic cancer. The other 97 patients included 57 men and 40 women, ranging from 19 to 76 years old (mean: 50.8 years). Fifty-six patients had concurrent myasthenia gravis (MG), 4 had pure red cell aplasia (PRCA), and 1 had hypogammaglobulinemia. Methods : The 97 thymoma patients were divided into groups based on their concurrent autoimmune diseases and the WHO classification of their tumors. Then the survival rate of the 56 and 41 patients with or without MG, respectively, as well as the 4 and 93 patients with or without PRCA, was compared retrospectively. Results: MG was frequently associated with WHO type B1, B2, or B3 thymomas. According to the Masaoka staging system, the mean stage of thymomas associated with MG was 1.79, while the mean stage of thymomas without MG was 1.37.Among the 4 thymomas associated with PRCA, one was type AB, one was type B2, and two were type B3.The 56 patients who had thymomas associated with MG did not show a significant difference in survival from the 41 patients who had thymoma without MG (P=0.4240). However, there was a significant difference in survival between the 4 patients who had thymoma associated with PRCA. and the 93 patients without PRCA (P=0.0030). Conclusion: MG was common in patients with WHO type B1, B2, or B3 thymomas. The presence of MG had no significant influence on survival relative to that of thymoma patients without MG. The survival of patients who had thymoma with concurrent PRCA was significantly worse than that of patients without concurrent PRCA.