Michael is a junior doctor working at Sir Charles Gairdner Hospital with a special interest in education and physician medicine.
Giant Cell Arteritis- A Diagnostic Challenge Affecting The Elderly
A 78-year-old man presented to hospital with a one-month history of headache, insomnia and documented high-grade fevers. His chief complaint was a persistent, central headache localised to the vertex. He described recent unintentional weight loss of 30kg in the preceding six months. He denied jaw claudication and scalp tenderness.
Initial bloodwork showed a mild normocytic anaemia. C-reactive protein was 264 mg/L (RI, <10 mg/L) and erythrocyte sediment rate was 95 mm/hr (RI, 1-30 mm/hr). Extensive imaging including temporal artery ultrasound and positron emission scanning were normal.
A blind temporal artery biopsy was performed, demonstrating giant cell arteritis (GCA). The patient was commenced on 50mg prednisolone daily with rapid resolution of his headache and no further febrile episodes.
In the absence of characteristic symptoms, GCA can be an exceedingly elusive diagnosis, likely contributing to its underdiagnosis in the community. However, timely diagnosis is crucial in preventing potentially catastrophic sequelae including stenosis, aneurysm formation and irreversible blindness. Temporal artery ultrasonography has relatively poor sensitivity for GCA, especially in those with low to moderate pre-test probability. Meta-analysis has shown that 18F-fluorodeoxyglucose positron emission/computed tomography (FDG PET) has a sensitivity of just 83.3% and specificity of 89.6% for giant cell arteritis.
Biopsy remains the gold standard for definitive GCA diagnosis. It is therefore crucial for physicians to be aware of the limitations of ultrasonography and PET scans in diagnosis and progress to biopsy if clinical suspicion remains.
Clinical Practice Points: