An Arachnoid Cyst Incidentally Found in a Young Man Who Died of Sudden Cardiac Death

An arachnoid cyst is a rare cerebrospinal fluid–filled non-neoplastic cystic lesion. Most arachnoid cysts are asymptomatic; however, depending on their location and size, they may show various clinical symptoms and rarely can cause serious complications. We report a case of an arachnoid cyst incidentally found in a 25-year-old male soldier, which was not the cause of death. A 2.3×1.7 cm unilocular cystic lesion filled with colorless serous fluid was observed near the interpeduncular fossa of the brain. Microscopy revealed the cyst membrane to be lined by a single layer of meningothelial cells with no edema or inflammatory reaction in the surrounding structures. Considering the medical history, circumstances of death, and autopsy findings, the cause of death was determined to be sudden cardiac death, and the cyst found in the brain was consistent with an arachnoid cyst. Reviewing this case and related literature would help to determine the cause and manner of death if an arachnoid cyst is incidentally found during an autopsy.