Pulmonary artery aneurysm as a rare manifestation of giant cell arteritis

A female patient in her 70s with a remote history of vocal cord paralysis was incidentally found to have a pulmonary artery aneurysm on a chest CT. Serial imaging performed over 3 years noted enlargement beyond 5.5 cm, prompting surgical repair. Histopathological examination revealed granulomatous arteritis with multinucleated giant cells and disruption of the elastic lamina, consistent with large-vessel giant cell arteritis (GCA). The patient was treated with corticosteroids and subsequently transitioned to subcutaneous tocilizumab, achieving postoperative stability on imaging and normalisation of inflammatory markers.This case highlights an unusual presentation of GCA with isolated pulmonary artery involvement, underscoring the diagnostic value of surgical tissue biopsy and the importance of considering vasculitis in aneurysmal disease, even in the absence of systemic manifestations.