Sudden Death Due to Recent Hemorrhage From an Intrathoracic Chronic Expanding Hematoma

Chronic expanding hematoma (CEH) is a rare disease that can develop in any region of the body, but it most frequently develops in the thorax. When intrathoracic CEH is left untreated, gradually expanding hematoma can be life‐threatening, leading to respiratory failure or hemoptysis. We encountered an 89‐year‐old man with cardiopulmonary arrest on arrival. He had been healthy, and it was unclear whether CEH had previously been detected. A very large mass was observed on chest computed tomography (CT), but the cause of death could not be determined. In the autopsy, this mass was identified as CEH and no malignant findings were noted. A fresh hemorrhage had occurred in the hematoma and perforated the bronchial lumen, which caused airway obstruction/asphyxia and resulted in sudden death. CEH should be suspected when a very large tumorous lesion occupying the entire hemithorax is observed on chest imaging, and it is important to recognize that sudden death can occur in the natural course of CEH.