Objective: To investigation the clinical characteristics in myasthenia gravis (MG) patients with thymomas.
Methods: A total of 856 MG patients admitted to the department during 2008.7 - 2010.12 were reviewed retrospectively. The patients with MG were divided into two groups based on thymic pathology, which were 162 cases with thymoma and 694 cases without thymoma. We compared the different clinical features including the gender, age of onset, MG symptoms and the incidence rate of myasthenia crisis. And the relationship between the WHO types, Maosaoka stages of thymoma and the severe of MG was also studied.
Results: The percentage of thymoma-associated MG patients was 18.9 percent of hospitalized MG patients at the same period. Of the 162 thymoma-associated patients, 94 were male and 68 were female, with a ratio of 1.38:1 and a mean age of (42.9 ± 12.4) years old. Thymoma was more frequent in middle-old aged patients than in children. Compared with non-thymoma MG, more thymomatous patients showed generalised MG, but not only ocular muscles weakness (90.1% vs 62.4%, P < 0.001). There were significant differences of the incidence rate of myasthenic crisis in the two groups (14.8% vs 2.3%). (2) WHO type B2 and Maosaoka I, II thymoma were the commonest types among all potentially MG-associated thymoma. No differences of Osserman MG classification was found in thymomatous patients with different pathologic changes.
Conclusions: The thymomatous MG patients had its distinctive clinical features: thymomas occurred in about 19.7% of MG patients with more men than women, more common in generalized, higher incidence of myasthenia crisis, with B2 type thymic pathology and Maosaoka I, II stages. No correlation was found between pathologic and clinical stages.