Ectopic Thymoma in the Thorax With Associated Myasthenia Gravis

A 52-year-old man presented with a one-year history of episodic unilateral facial numbness, jaw weakness, ptosis, and hoarseness. Brain imaging was unremarkable and an 11.5cm right lower thoracic mass was discovered on chest x-ray, which was further evaluated by CT and MRI radiology. The lesion was biopsied, and histopathological examination revealed a thymoma. A diagnosis of ectopic thymoma with paraneoplastic myasthenia gravis was supported by positive anti-acetylcholine receptor and anti-titin serum antibodies. Paraneoplastic syndromes are rarely reported in association with ectopic thymoma, making this case unusual. We discuss the nuances of diagnosis, classification, and staging of this rare case, as well as the patient's subsequent management by cardiothoracic surgery and neurology specialists.