Giant cell arteritis (GCA) affects large and medium vessels, particularly the superficial temporal, ophthalmic, and posterior ciliary arteries in patients over 50. The most feared complication is irreversible vision loss. Which histological finding in a temporal artery biopsy is most specific for GCA versus other granulomatous vasculitides?

• A Transmural infiltration by neutrophils and fibrinoid necrosis of the media, as seen in microscopic polyangiitis
• B Concentric intimal proliferation with luminal compromise and no inflammatory infiltrate (endarteritis obliterans), as seen in Buerger disease
• C Fibrinoid necrosis of adventitial vessels (vasa vasorum) with eosinophil-rich infiltrate, as seen in Churg-Strauss syndrome
• D Granulomatous inflammation centered on the internal elastic lamina with multinucleated giant cells, disruption of the IEL, and lymphocytic infiltration of the media; skip lesions on biopsy (alternating involved and uninvolved segments) are characteristic ✓

Explanation

Temporal artery biopsy in GCA shows panarteritis (all three layers involved) but with a predilection for the inner media and internal elastic lamina (IEL). Hallmarks are granulomatous inflammation with Langhans-type or foreign-body-type multinucleated giant cells clustered at the IEL, fragmentation and disruption of the IEL (on EVG stain), lymphocytes (predominantly CD4+ Th1 and Th17 cells), and macrophages. Intimal proliferation causes luminal narrowing. Skip lesions (segments of normal artery between inflamed segments) mean a negative biopsy does not exclude GCA — a long biopsy (>2 cm) is recommended. Steroid therapy must be started urgently to prevent ischemic optic neuropathy before biopsy confirmation.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.