A colloid cyst of the third ventricle -- the cause of episodic headache and sudden unexpected death in an adolescent girl.

An 18-year-old girl was found dead in her bed. The autopsy revealed a colloid cyst of the third ventricle. The cyst obstructed the flow of cerebrospinal fluid, leading to prominent internal hydrocephalus with consecutive brain edema and compression of the caudal medulla at the foramen magnum. The girl's only previous complaints were episodic headaches for the previous 2-3 years. Computed tomography and magnetic resonance imaging were not performed prior to her death. This case report highlights the importance of early diagnosis of colloid cyst of the third ventricle and the need to perform computed tomography and magnetic resonance imaging in patients with episodic headaches even when they show no neurologic deficit. Although it is a very rare disorder, it should be included in the differential diagnosis of headaches in children and young adults, and also in the differential diagnosis of conditions causing increased intracranial pressure, in view of the life-saving management required to prevent a fatal outcome.