Pulmonary vasculitis mimicking chronic thromboembolic disease.

A 29-year-old female patient presented with chest pain, breathlessness and syncope on the background of constitutional symptoms, oral ulceration and a rash. Multiple investigations were performed, including a CT pulmonary angiogram (CTPA) that was initially felt to show imaging features consistent with a diagnosis of chronic thromboembolic disease (CTED). The patient was referred to a tertiary pulmonary hypertension centre and the possibility of pulmonary vasculitis was raised. Subsequent positron emission tomography (PET)-CT revealed imaging features supporting this diagnosis. The patient was treated with intravenous cyclophosphamide infusions, following which her symptoms improved. A repeat PET-CT 6 months after treatment showed resolution in pulmonary artery and mediastinal uptake, but persistence of pulmonary artery occlusions on a repeat CTPA. A final diagnosis of pulmonary vasculitis secondary to Behçet's disease was made. This case report aims to raise awareness of the imaging features of CTED and its mimics.