Pulmonary artery pseudoaneurysm with massive hemoptysis secondary to lung adenocarcinoma: A case report and literature review.

RATIONALE: Pulmonary artery pseudoaneurysm (PAP) is a rare but life-threatening vascular complication, often associated with infections, trauma, or malignancies. Rupture of PAP can lead to massive hemoptysis with high mortality. Lung cancer-related PAP is exceptionally rare, particularly in adenocarcinoma, and is underrecognized due to its small size and subtle imaging findings. PATIENT CONCERNS: A 47-year-old woman with low back pain for 3 months was diagnosed with right lower lobe lung adenocarcinoma (cT2bN0M1, IVa). After chemoradiotherapy, the tumor regressed but formed a cavity. She subsequently developed sudden massive hemoptysis (400 mL), leading to airway obstruction and death. DIAGNOSES: Imaging revealed a soft-tissue mass invading the right lower pulmonary artery, with subsequent formation of a small PAP (0.5 × 0.4 cm). Biopsy confirmed lung adenocarcinoma. Retrospective computed tomography analysis identified the PAP, attributed to tumor invasion and treatment-induced vascular damage. INTERVENTIONS: The patient underwent intensity-modulated radiotherapy (40Gy/20F) followed by 4 cycles of chemotherapy (pemetrexed, bevacizumab, and cisplatin). After hemoptysis, PAP embolization was planned but not performed due to rapid clinical deterioration. OUTCOMES: Despite initial tumor stabilization, the patient succumbed to fatal hemoptysis caused by PAP rupture. A posthumous multidisciplinary review confirmed the pseudoaneurysm as the cause. LESSONS: Enhanced vascular monitoring is essential in lung cancer patients, especially during tumor regression and posttreatment phases. Small PAPs, though subtle, carry lethal potential. Early detection and multidisciplinary intervention are critical to prevent fatal outcomes.