A Rare Case of Sudden Death due to Rupture of Saccular Descending Thoracic Aortic Aneurysm with Dissection.

Ruptured descending thoracic aortic aneurysm (DTAA) is a rare event and remains asymptomatic in over 95% of cases, often leading to the under-detection of most thoracic aortic aneurysms (TAAs) unless incidentally discovered during routine imaging, medical examinations, or autopsy following sudden death. This case report presents a 56-year-old male with a history of hypertension and diabetes mellitus who was managed with regular medication, collapsed suddenly, and was found unconscious. Emergency medical services declared him dead on arrival. An autopsy examination disclosed 2750 g of blood in the left pleural cavity and a 2.5 cm transverse tear in a saccular aneurysm on the descending thoracic aorta with aortic dissection (AD). Histopathological analysis confirmed necrosis, fibrosis, and a mixed inflammatory infiltrate at the rupture site, with features consistent with healed myocardial infarction and grade VII atherosclerosis. This case underscores the importance of recognizing the silent yet fatal nature of saccular aneurysms in the descending thoracic aorta.