A 45-year-old woman presents with right orbital pain worsening on eye movement, scalp tenderness, and jaw claudication. ESR is 98 mm/h and CRP 66 mg/L. Temporal artery biopsy is being planned. What histological finding is diagnostic of giant cell arteritis (GCA)?
- A Granulomatous inflammation with disruption of internal elastic lamina and multinucleate giant cells ✓
- B Neutrophilic infiltration of all layers with fibrinoid necrosis — classic polyarteritis pattern
- C Concentric intimal hyperplasia without inflammatory cells — characteristic of Takayasu
- D IgA deposits in small vessel walls — diagnostic of IgA vasculitis
Explanation
GCA is a granulomatous vasculitis of medium and large vessels; temporal artery biopsy characteristically shows transmural granulomatous inflammation with giant cells (multinucleate histiocytes), disruption and fragmentation of the internal elastic lamina, and intimal hyperplasia causing luminal narrowing. Skip lesions occur, so biopsy length should be ≥ 2 cm and bilateral biopsy improves sensitivity. Fibrinoid necrosis with neutrophils suggests polyarteritis nodosa. Takayasu shows adventitial fibrosis and intimal hyperplasia but with different vessel distribution. IgA deposits are diagnostic of IgA vasculitis (Henoch-Schönlein).
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.