A Case of Giant Cell Arteritis Presenting With a Hyperechoic Wall Thickening on Temporal Artery Ultrasonography.

Giant cell arteritis (GCA) is a type of systemic vasculitis in older adults that requires prompt diagnosis to prevent ischemic complications. Temporal artery (TA) ultrasonography is widely used as an initial diagnostic tool and typically demonstrates a hypoechoic halo sign. We report the case of a 91-year-old man with polymyalgia rheumatica who developed fever, malaise, proximal joint pain, and jaw claudication during steroid tapering. TA ultrasonography (linear 25 MHz, short-axis, non-compressible) revealed circumferential hyperechoic wall thickening rather than the typical halo sign, raising the suspicion of atherosclerotic changes. However, positron emission tomography-computed tomography demonstrated fluorodeoxyglucose uptake in the bilateral TAs and periarticular regions, and a TA biopsy confirmed GCA with lymphocytic infiltration and multinucleated giant cells. The patient was treated with high-dose prednisolone and tocilizumab and subsequently showed clinical improvement. This case highlights the atypical sonographic presentation of GCA mimicking degenerative arterial changes. Awareness of such atypical findings and the integration of clinical, imaging, and histopathological findings are crucial to avoid misdiagnosis and ensure timely management.