A Quiet Rupture: Hemodynamically Stable Ruptured Descending Thoracic Aortic Aneurysm Presenting as Lower Respiratory Tract Infection.

The rupture of a descending thoracic aortic aneurysm (DTAA) is a rare but critical vascular emergency that requires immediate recognition and action. It usually presents as a sharp, severe pain in the chest or back; however, some individuals exhibit non-typical symptoms resembling respiratory infections, leading to misdiagnosis and delays in definitive treatment. A 63-year-old male with a history of hypertension and smoking presented with left-sided chest pain to another hospital, where he was diagnosed with unstable angina based on clinical suspicion and managed conservatively with anti-anginal medication. Over the next three days, the patient developed a persistent cough, low-grade fever, and pleuritic pain, prompting referral to our hospital, where a lower respiratory tract infection (LRTI) was considered. On arrival, he was hemodynamically stable with a systolic BP of 100 mmHg and was managed with intravenous fluids, antibiotics, and nebulizers. Chest X-ray revealed moderate left pleural effusion with tracheal deviation, and thoracic ultrasound confirmed internal echoes suggestive of hemorrhagic content. Diagnostic thoracentesis yielded hemorrhagic fluid, prompting high-resolution computed tomography (HRCT), which showed a partially thrombosed 54 mm × 49 mm saccular aneurysm of the descending thoracic aorta with left lung collapse. Despite the rupture, the patient remained hemodynamically stable, suggestive of a contained event. A subsequent computed tomography angiogram (CTA) confirmed rupture into the pleural space and was the imaging modality that established the final diagnosis. The patient underwent thoracic endovascular aortic repair (TEVAR) using a 30 mm × 30 mm × 120 mm Ankura graft, selected for its conformability and effective sealing profile in emergencies. Postoperative recovery was uneventful. A CT aortogram on day three confirmed complete exclusion of the aneurysm with no endoleak, and a follow-up chest X-ray at two weeks showed full resolution of the hemothorax. This case illustrates the diagnostic challenge posed by atypical ruptured DTAA presentations and reinforces the importance of early CTA in unexplained pleural effusions, even in stable patients. Structured post-TEVAR surveillance remains critical to ensure long-term outcomes.