Normal ESR, CRP and Platelet Count in Giant Cell Arteritis and Polymyalgia Rheumatica: A Diagnostic Conundrum

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are both rheumatological diseases of the elderly with a strong association with each other and which rarely present with normal inflammatory markers. Here we present the case of a 61-year-old Caucasian woman who had typical symptoms of both diseases. At the time of presentation, her blood work showed normal inflammatory markers, but because of the high clinical suspicion for GCA, a temporal artery biopsy was done which was positive for giant cells and disruption of the internal elastic lamina. Our patient responded very well to treatment with oral steroids and steroid-sparing medication and was able to return to her normal life without experiencing any complications of the disease. By sharing our case, we aim to increase the awareness of medical personnel regarding the importance of focusing on the clinical presentation as well as the laboratory and pathological aspects of diagnosing GCA and PMR. LEARNING POINTS: Normal levels of inflammatory markers like C-reactive protein and the erythrocyte sedimentation rate do not rule out the diagnosis of giant cell arteritis (GCA). We aim to increase clinician recognition and awareness of other parameters, particularly the clinical presentation, that should be considered when diagnosing GCA or polymyalgia rheumatica. If the index of suspicion for the disease is high, it is crucial to start treatment as early as possible for better management and to avoid harmful complications.