A thymic cyst presenting as first episode 'status epilepticus'

and importance: We report a rare case of unusual initial neurologic presentation of congenital thymic cyst, which generally is asymptomatic and therefore require additional radiological evaluation. The diagnosis, however, is by histological confirmation after surgical excision.

Our patient presented with first time status epilepticus from an infected congenital thymic cyst, resulting in acute cerebral edema. Although initially missed, a careful re-evaluation of chest X-ray provided the diagnostic clue of a mediastinal mass effect on cerebral venous drainage. Cyst excision resulted in clinical and radiological resolution of cerebral edema.

Although superior mediastinal masses are known to cause convulsions from cerebral edema, congenital thymic cysts rarely cause neurological symptoms and are therefore least expected to present in the emergency department with first time status epilepticus. However, a careful evaluation of the superior mediastinum on chest radiographs is helpful to identify such an example of extra-cranial etiology of this neurological emergency.

Acute increase in pressure and or size from localized cyst infection of a congenital thymic cyst may cause acute cerebral edema from acute SVC obstruction, with resultant acute neurological symptoms.