A Rare Case of Giant Cell Arteritis Affecting Two Giants: Pulmonary and Root of Aorta Aneurysm.

Aneurysms of pulmonary arteries and aorta are rare, typically caused by infections, congenital heart defects, vascular abnormalities, or medical interventions. This report presents an unusual case of a 72-year-old man with a history of smoking, hypertension, and emphysema, who was found to have a large pulmonary artery aneurysm (63.5 mm) and aortic root dilation (46 mm). Despite normal inflammatory markers and no typical giant cell arteritis (GCA) symptoms, histopathology following surgical repair revealed focal GCA as the underlying cause. The patient underwent successful valve-sparing root replacement and was subsequently treated with prednisone and tocilizumab, showing clinical improvement. This case underscores the existence of a rare GCA phenotype-extracranial GCA-that affects major arteries without cranial involvement and often lacks classic symptoms. Extracranial GCA carries serious risks, including dissection and rupture, particularly in hypertensive individuals. The continuous inflammation in GCA leads to medial degeneration and aneurysm formation. Advancements in imaging have improved early detection and intervention, though the rarity of this condition limits large-scale studies. As a result, diagnosis and treatment rely heavily on case reports. Glucocorticoids and immunomodulators remain the mainstay of therapy, but more research is needed to optimize management for this atypical GCA presentation.