Introduction: Sarcoidosis is a multisystem granulomatous disease with heterogeneous clinical expression. Although cardiac involvement is well established, large-vessel sarcoidosis, particularly aortic involvement, remains rare and underrecognized. Vascular involvement may be associated with structural aortic complications, including aneurysm formation and valvular dysfunction, potentially leading to adverse outcomes. 18F-FDG PET-CT is a key imaging modality for detecting active inflammation and unsuspected vascular involvement.

Clinical Case Description: We report a case series of three patients with systemic sarcoidosis in whom PET-CT demonstrated metabolic activity involving the thoracic aorta. Clinical, imaging, and therapeutic data were retrospectively reviewed.

A 64-year-old woman with long-standing multisystem sarcoidosis and prior supraventricular tachycardia requiring ablation developed progressive aortic valve disease and ascending aortic involvement requiring surgical replacement. Histopathology revealed non-caseating granulomas. 18F-FDG PET-CT showed persistent uptake in the ascending aorta (SUVmax 6.57) and aortic valve region (SUVmax 4.27). She had been managed without systemic corticosteroids, receiving only inhaled therapy.

A 54-year-old woman with biopsy-proven pulmonary sarcoidosis was asymptomatic and receiving methotrexate after disease relapse. PET-CT demonstrated heterogeneous FDG uptake along the ascending thoracic aorta (8–9 cm; SUVmax 6.6) with additional uptake at the aortic valve (SUVmax 4.3), consistent with active large-vessel inflammation.

A 57-year-old woman with sarcoidosis and prior breast cancer was asymptomatic and only on inhaled treatment. 18F-FDG PET-CT demonstrated focal uptake in the ascending aortic wall despite unremarkable conventional imaging.

Conclusions: This case series highlights the rarity of aortic involvement in sarcoidosis, which is often asymptomatic and incidentally detected. 18F-FDG PET-CT identifies subclinical large-vessel disease, expanding the recognized spectrum of sarcoidosis. Aortic involvement has been associated with structural complications and potential vascular risk, supporting the need for close clinical and imaging surveillance. Further studies are required to clarify its prognostic significance.