Further expanding the clinical spectrum of giant cell arteritis: Non-classical organ involvement and uncommon complications.

The increasing use of imaging techniques, particularly 18F-FDG PET-CT, together with autopsy findings, has significantly expanded our understanding of the clinical spectrum of giant cell arteritis (GCA). This study aimed to assess the frequency and spectrum of non-classical manifestations and other infrequent complications of the disease METHODS: This retrospective study analyzed a consecutive cohort of 174 patients with proven GCA diagnosed between 2005 and 2024. Among 174 GCA patients, 52 (29.9%) presented with one or more non-classical organ manifestations, including cardiac involvement in 7.5% (ischaemic heart disease or pericarditis), primary respiratory disease in 13.8% (pleural disease, sore throat, persistent dry cough, interstitial lung disease, and pulmonary inflammatory nodules), neurological complications beyond strokes in 2.3% (peripheral neuropathy, epilepsy, and spinal cord infarction), gastrointestinal involvement in 1.1%, and increased 18F-FDG uptake in salivary glands in 5.7%. Beyond these manifestations, PET-CT at diagnosis revealed uncommon medium-to-large vessel involvement, including renal artery vasculitis in 2.9% (without renal insufficiency or urinary abnormalities) and asymptomatic splanchnic involvement (coeliac trunk or superior mesenteric artery) in 4.6%. Other infrequent manifestations included secondary amyloidosis in 1.1%, necrosis or involvement of the scalp, tongue, or lips in 2.3%, carotidynia in 5.2%, overt audiovestibular involvement (including sensorineural hearing loss or vestibular dysfunction) in 3.4%, musculoskeletal symptoms beyond PMR in 10.3% (peripheral arthritis and remitting distal extremity swelling with pitting oedema), diffuse increase in bone marrow 18F-FDG uptake in 15.5%, and polyautoimmunity in 10.3%. Beyond the classical cranial and extracranial patterns, which often coexist, a significant proportion of GCA patients may present with atypical or non-classical complications, sometimes as the initial manifestation. These should be considered during evaluation and follow-up, as early recognition and treatment are key to reducing morbidity and mortality.