Thursday, June 14, 2018

A Primer on Giant Cell (Temporal) Arteritis

Neuropathologists are often tasked with handling ophthalmic pathology at their institutions. As such, they are assigned all cases submitted by ophthalmologists -- including temporal artery biopsies for determination of the presence of active giant cell (temporal) arteritis. What follows is a quick reference on the important points to remember about giant cell arteritis. (If there are things I am forgetting, please add your comments.):

Arrow points to a giant cell in a temporal artery wall
(from Robbins Basic Pathology, 10th edition)
Refering to the condition as "temporal arteritis" is not entirely accurate as giant cell arteritis is a granulomatous inflammatory disorder that can affect a variety of large and small arteries in the head. In addition to the temporal artery, ophthalmic arteries can be affected (which is the reason ophthalmologists are often the clinicians performing biopsies in suspected cases). Additionally, vertebral arteries and even the aorta (giant cell aortitis) can be involved. Since ophthalmic arteritis can lead to sudden and irreversible blindness, affected patients must be promptly diagnosed and treated. A negative biopsy result does not entirely exclude the diagnosis as the distribution of inflammation is often patchy.

Because pathologic changes tend to be patchy, examination of several cross-sectional levels is required. Involved segments exhibit nodular intimal thickening (and occasional thromboses). Most lesions exhibit granulomatous inflammation within the inner media which disrupts the internal elastic lamina. A minority of cases do not show either granulomas or giant cells, instead exhibiting only a non-specific acute and chronic inflammatory infiltrate. Healing is characterized by intimal thickening, medial thinning, and adventitial fibrosis.

Reference: Kumar V, Abbas AK, and Aster JC (eds.) Robbins Basic Pathology, Chapter 10 "Blood Vessels", 10th Edition (2018) pp. 384-5.

No comments: