Vnitr Lek 2026, 72(5):E27-E33 | DOI: 10.36290/vnl.2026.065

Giant cell arteritis with a mixed cranial and large-vessel phenotype presenting with atypical retroauricular headache and fever of unknown origin

Marcel Pavlík¹, Oliver Kuchař¹, Róbert Novotný²

¹ Interní klinika Fakultní nemocnice Bulovka a 3. LF UK, Praha

² Chirurgická klinika 3. LF UK a Fakultní nemocnice Královské Vinohrady, Praha

Giant cell arteritis is the most common primary large-vessel vasculitis affecting individuals older than 50 years. The classical cranial form is typically associated with temporal headache, jaw claudication, scalp tenderness, visual disturbances, and the risk of irreversible vision loss. However, the disease may also present as fever of unknown origin accompanied by a marked systemic inflammatory response without typical temporal artery involvement, leading to substantial diagnostic delay. We present the case of a 62-year-old woman with an approximately two-month history of right-sided retroauricular and occipital headache, daily febrile episodes, C-reactive protein levels repeatedly exceeding 100 mg/L, erythrocyte sedimentation rate above 100 mm/h, normocytic anemia, and reactive thrombocytosis. Repeated courses of antibiotic therapy were ineffective. Extensive infectious, otorhinolaryngological, neurological, and cardiological investigations, including brain CT and CT angiography, echocardiography, and basic oncological screening, failed to identify the cause of her symptoms. Ultrasonography of the temporal arteries did not demonstrate the characteristic halo sign, and temporal artery biopsy showed no histopathological evidence of vasculitis. During the diagnostic workup, the patient developed unilateral visual impairment of the right eye with visual field defects and findings consistent with ischemic optic neuropathy. After exclusion of the major infectious differential diagnoses, systemic glucocorticoid therapy was initiated immediately because of a strong clinical suspicion of giant cell arteritis. Subsequent ^18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) revealed active large-vessel vasculitis with diffuse increased FDG uptake in the aortic wall and its major branches, most prominently in both subclavian arteries, without evidence of malignancy or an infectious focus. This case illustrates giant cell arteritis with a mixed cranial and large-vessel phenotype, in which extracranial involvement predominated in extent and imaging conspicuity, whereas cranial ischemic manifestations were clinically decisive. It also demonstrates that neither a negative temporal artery ultrasound examination nor a negative temporal artery biopsy excludes the diagnosis. In patients older than 50 years presenting with fever of unknown origin, newly developed headache, markedly elevated inflammatory markers, and ischemic ocular symptoms, FDG PET/CT may provide decisive diagnostic information and substantially contribute to establishing the correct diagnosis.

Keywords: giant cell arteritis, large-vessel vasculitis, fever of unknown origin, FDG PET/CT, ischemic optic neuropathy, temporal arteritis.

Accepted: August 20, 2026; Published: August 27, 2026  Show citation