[Giant cell arteritis diagnosed by a temporal artery biopsy without abnormal imaging and physical findings in an elderly patient presenting with fever].

Giant cell arteritis (GCA) is considered in the differential diagnosis of fever of unknown origin in the elderly. We describe the case of an 83-year-old man with GCA diagnosed by temporal artery biopsy (TBA), who did not exhibit abnormal physical and imaging findings. The patient had fever and elevated C-reactive protein (CRP), which had persisted for two months. He was examined and treated with antibiotics and antipyretic analgesics in a local clinic, but they had little effect. He was referred to us. He showed no abnormal physical findings. Image examinations, including ultrasonography, CT, MRI, and PET-CT, showed no abnormal findings. We performed TBA. The histological examination of the artery showed inflammatory cell invasion and rupture of the internal elastic membrane, indicating GCA. We initiated oral corticosteroid treatment. The patient's fever quickly disappeared and his CRP level returned to normal. TBA has been the gold standard for the diagnosis of GCA. However, TBA is an invasive procedure and the sensitivity depends on the operator's skill level. Recently, imaging examinations have frequently been used for the diagnosis of GCA. The sensitivity of imaging examinations is similar to that of TBA. However, our case did not show any abnormal imaging findings and was only diagnosed by TBA. This case suggested that TBA remains a useful examination for elderly patients with fever that persists for a long time.