Abstract
Fever of unknown origin is challenging to diagnosis, we have to distinguish between infections, malignancies, especially lymphoma, and autoimmune diseases such as vasculitis. Giant cell arteritis (GCA) is a chronic vasculitis of large and medium sized vessels, and can cause fever of unknown origin in elderly patients. A 78-year old female patient complained of fever and dry cough that persisted for more than two months without visual disturbance, polymyalgia rheumatica or new onset of localized headache. Her physical examination did not show any tenderness or reddishness of the temporal artery. Laboratory tests showed an elevated erythrocyte sedimentation rate (ESR) of 127 mm/hr, elevated C-reactive protein (CRP) of 6.4 mg/dL, and decreased serum albumin of 2.4 g/dL. FDG-PET showed subclinical inflammation in the aorta, and the sub-clavian, axillary, iliac, and femoral arteries, the common carotid and temporal arteries, although neither computed tomography nor Gallium scintigraphy showed any significant findings. A temporal artery biopsy confirmed the diagnosis of GCA. Brain magnetic resonance imaging showed a single small subacute cerebral infarction of the pons without any neurological abnormality. After oral administration of 40 mg-per-day of prednisolone, fever and dry cough disappeared in two days. Six months later, she has no symptoms under the administration of 15 mg-per-day of prednisolone, without any elevation of ESR or CRP. FDG-PET has a high sensitivity for the rapid detection of inflammatory sites through the body, which makes it a valuable diagnostic modality when used as a guide for early diagnosis of GCA.
