Non-thymoma thymic morphology in patients with Myasthenia Gravis / 中华胸心血管外科杂志

ABSTRACT

Objective:To investigate the non-thymoma thymic morphology in patients with Myasthenia Gravis(MG), and provide the theoretical basis for extended thymectomy.Methods:From September 2008 to March 2018, extended thymectomy had been performed for 150 patients with MG in our department. In order to achieve maximal benefit, combined thoracoscopic and mediastinoscopic approach had been adopted to completely remove both thymus and ectopic thymic tissue in the neck and the anterior mediastinum. Cervical and mediastinal tissue including fat from the thyroid isthmus to the diaphragm was swept away from above the phrenic nerve. The regions containing mediastinal fat were divided into 12 stations.Results:There was no mortality. Pathology reports revealed 126(84.0%) patients with MG had hyperplastic thymus, 17(11.3%)cases with involuted thymus and 7 (4.7%)cases with normal thymus. 98 (65.3%)cases had more than two superior horns, and 59(39.3%) patients had ectopic thymic tissue in the mediastinum and in the neck. Positive rates of ectopic thymic tissue in the 12 cervical-mediastinal fat stations were 7.8%, 10.0%, 8.8%, 3.8%, 3.0%, 2.5%, 0, 0, 0.7%, 13.3%, 12.3% and 9.1%, respectively. After a follow-up period of 2-12 years, the rate of complete stable remission was 44.7%(59/132), and the effective rate was 89.4%(118/132).Conclusion:It is very meaningful to study non-thymoma thymic morphology in patients with MG in order to guide the performance of extended thymectomy and improve its outcome. For the purpose of minimally invasion, one side of mediastinal pleural should be carefully protected.