RESUMO
BACKGROUND Castleman's disease is defined as a benign lymphoproliferative disorder of uncertain origin. It is most commonly found in the area of mediastinum. Castleman's disease is classified based on pathological features into hyaline-vascular, plasma cell, and mixed variants, which the hyaline-vascular variant is the commonest in association with Myasthenia Gravis. Castleman's Disease have been very rarely reported in Myasthenia Gravis, as it is associated with various clinical abnormalities. The enlarged localized lymph node is mainly diagnosed by incidental radiological findings due to the enlargement of thymus gland or by compression symptoms. CASE REPORT Here we report a case revolves around a 31-year-old Saudi woman who presented with a 2 years history of exertional dyspnea associated with mouth and eye ulcers. There were no other associated symptoms such as muscular weakness, rapid fatigue or drooping of the eyelids. She was referred to our institution for further investigations and management. She was diagnosed with a mediastinal thymoma that was detected based on a positive serology of antibody anti-acetylcholine receptor (AChR) testing and a computed tomography (CT) scan findings, she eventually underwent a bilateral thoracoscopic thymectomy. CONCLUSIONS The aim of this case report is to add more to the literature by reporting a rare case of an asymptomatic subclinical Myasthenia Gravis associated with Castleman's disease. It highlights the importance of considering a Castleman's Disease in an asymptomatic case who presented with a mediastinal mass and in order to avoid an unusual intraoperative finding such as massive bleeding by performing a biopsy and an angiography preoperatively.