Unexpected Preoperative Regression of a Thymoma: A Case Report

Abstract

We report a case of unexpected spontaneous regression of thymoma in a 44-year-old patient, referred with clinical, biological, and electrophysiological findings of Myasthenia gravis. The patient was stable on synthetic Acetylcholesterase inhibitors, immunosuppressants, and corticosteroids. A chest computed tomography (January 2020) revealed a well-defined tumor in the anterior mediastinum. Surgical removal was decided. Unfortunately, because of the covid 19 pandemic, the surgical activity of the department of thoracic surgery was suspended. The patient was discharged and re-admitted nine months later. A new chest computed tomography (September 2020) was performed, revealing a net regression of the anterior mediastinal tumor. The long axis of the tumor decreased from 97mm to 28mm. A Video-assisted thoracoscopic thymothymectomy was performed. The histopathological study of the specimen revealed a Thymoma B3, according to the world health organization (WHO) classification, without any necrosis, hemorrhagic or sclerotic cells. The spontaneous regression of thymic epithelial tumors is reported as rare. Surgical excision should be performed, even if tumor volume regression is observed. After surgical resection, the anatomopathological studies of the specimens could sometimes find some elements that explain the regression of these tumors. In our case, we suppose that the intake of corticosteroids by our patient could have played a role in this tumor regression.