Unusual Presentation of Giant Cell Arteritis With Localised Temporal Artery Aneurysm

Giant cell arteritis (GCA) is a granulomatous vasculitis of medium and large-sized arteries occurring in older adults. Skip lesions are well described, but to our knowledge, localised aneurysm formation in the context of normocalcaemic, non-progressive GCA has not been reported. We report a case of a 74-year-old male who presented with painless left-sided temporal artery swelling, with an aneurysm and halo sign on ultrasound Doppler (US Doppler). Inflammatory markers were normal. Biopsy of the affected segment confirmed granulomatous inflammation with giant cells. Without treatment, he remained well with subsequent normal inflammatory markers and the US Doppler and positron emission tomography (PET)-CT scan showing no progression of the disease.  This case illustrates the wide spectrum of giant cell arteritis, with the inflammation here being restricted to a focal segment of the superficial temporal artery with normal inflammatory markers and no apparent progression or similar isolated pockets in other areas. The temporal artery aneurysm is also a complication that has not been seen before in the context of GCA. This highlights the importance of considering a diagnosis of GCA, even in the absence of a classical presentation and laboratory findings, based on a potential complication that can help uncover the underlying issue.