Halo Sign on Temporal Artery Ultrasound Aids in Prompt Diagnosis of Giant Cell Arteritis

Giant cell arteritis (GCA) is the most common form of systemic vasculitis in individuals over 50 years old. The most feared complication of GCA is permanent blindness, which can be prevented by prompt diagnosis and immediate treatment. For many years, temporal artery biopsy (TAB) was considered the gold standard for diagnosing GCA. However, TAB can produce considerable false negatives if unaffected arterial segments are sampled. Several studies have shown that temporal artery ultrasound (TAUS)-a noninvasive, inexpensive, and quick diagnostic procedure-offers great sensitivity and enables efficient and prompt diagnosis. Additionally, it helps in identifying the diseased arterial segments sampled with TAB. For these reasons, TAUS is an appropriate complement or possible alternative to biopsy. However, the sequence in which these modalities are performed is crucial: performing the TAB first causes occlusion of the temporal artery, making it impossible to properly conduct the TAUS afterwards. Here, we present a case of a 70-year-old woman who showed symptoms indicative of GCA. In this case, the TAB was delayed twice, thereby allowing TAUS to be performed first and promptly. The presence of a halo sign on the TAUS confirmed GCA, which was later validated via TAB. This case highlights the advantages and benefits of conducting the less-invasive TAUS before the TAB.