|Arrow points to a giant cell in a temporal artery wall|
(from Robbins Basic Pathology, 10th edition)
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.