The histopathological structures of the extrapleural hematoma wall: A case report.

Extrapleural hematoma is a rare condition in which blood is present in the extrapleural space, which sometimes causes death due to respiratory failure. Although a single low-density stripe, called a "displaced extrapleural fat sign," can be detected in chest computed tomographic (CT) scans, no reports have confirmed this structure histopathologically. We performed an autopsy on a patient with extrapleural hematoma who died of respiratory failure. An extrapleural fat sign was detected on the antemortem CT. We investigated the wall structure histopathologically. The hematoma wall was composed of parietal pleura, a sub-pleural layer, an extrapleural fat layer and endothoracic fascia. The case indicated that extrapleural hematoma occurs at the endothoracic fascia.