Bronchial Artery-Pulmonary Artery Fistula Masquerading as Pulmonary Embolism: A Diagnostic Pitfall in Patients with Chronic Lung Disease

Background: Bronchial artery pulmonary artery fistula (BPAF) is a rare vascular malformation characterized by abnormal communication between the bronchial and pulmonary arteries. In the pulmonary arterial phase of computed tomography pulmonary angiography (CTPA), BPAF can present as a "segmental filling defect," which is easily diagnosed as pulmonary embolism (PE). Critically, misdiagnosis as PE may lead to the initiation of anticoagulation therapy, posing a risk of inducing or exacerbating hemoptysis. Methods: We retrospectively analysed data from 15 patients initially diagnosed with PE based on CTPA but subsequently confirmed BPAF by digital subtraction angiography (DSA). Clinical presentations, imaging characteristics, and outcomes were evaluated. Results: All patients had underlying chronic respiratory diseases (chronic obstructive pulmonary disease [COPD]: 40%, bronchiectasis: 73%, pulmonary tuberculosis: 20%, interstitial lung disease [ILD]: 7%). The main symptoms included dyspnea (60%), hemoptysis (80%), and chest pain (7%). Initial CTPA suggested PE in all patients, but subsequent DSA confirmed BPAF without evidence of thrombi. Hemostasis was achieved immediately after embolization in all patients with hemoptysis. Misdiagnosis led to inappropriate anticoagulation therapy in 14 patients (93%), with one experienced worsened hemoptysis. Conclusion: BPAF is an underrecognized PE mimic in patients with chronic lung disease. DSA is crucial for definitive diagnosis to avoid harmful anticoagulation. Clinicians should maintain a high index of suspicion for BPAF when encountering PE-like imaging findings in patients with structural lung disease.