A rare bilateral spontaneous severe hemothorax in intramural hematoma type B with unremarkable aortic histology: a case report and literature review.

Aortic intramural hematoma type B (IMHB) is a serious aortic condition characterized by crescentic thickening of the descending aorta, resulting from hemorrhage within the aortic wall, which may occasionally present with focal intimal disruption while still remaining distinct from classic aortic dissection. We report a fatal case of a 61-year-old male with a history of untreated arterial hypertension who presented with acute chest pain initially mimicking anterior ST-elevation myocardial infarction (STEMI). Computed tomography (CT) revealed an acute type B aortic syndrome with intramural hematoma and a focal entry-like intimal disruption behind the left subclavian artery, associated with suspected extravasation, hemomediastinum, and bilateral spontaneous massive hemothorax. Autopsy confirmed IMHB with rupture and pseudoaneurysm formation, the immediate cause of death was hemorrhagic shock due to aortic rupture. Histologic examination, including special stains (elastic van Gieson and Alcian blue), revealed no elastic fiber fragmentation, no mucoid extracellular matrix accumulation, and no cystic medial degeneration. This case illustrates a rare and fulminant presentation of bilateral spontaneous hemothorax complicating IMHB without identifiable histologic aortopathy. Although overall in-hospital mortality in uncomplicated IMHB is low, complications such as aortic rupture with bilateral hemothorax carry dramatically higher mortality.