Which histologic findings indicate late giant cell arteritis (GCA) (temporal arteritis)?

Updated: Sep 10, 2020
  • Author: Mythili Seetharaman, MD; Chief Editor: Herbert S Diamond, MD  more...
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All layers are affected in late cases or regions of arteries with marked involvement. There are widespread areas of necrosis of portions of the arterial wall. The elastic laminae usually are involved, and granulomas containing multinucleated histiocytic and foreign body giant cells, histiocytes, predominantly helper T-cell lymphocytes, and some plasma cells and fibroblasts are usually present.{ref7

Weyand and colleagues have extensively described the distribution and function of inflammatory cells in the artery wall. [140] Eosinophils may be seen in the specimen section, but polymorphonuclear leukocytes (PMNs) are rare. Thrombosis may develop at the sites of active inflammation. These areas with thrombosis may recanalize later.

It has been observed that the inflammatory process is usually most marked in the inner portion of the media adjacent to the internal elastic lamina. This has led to the belief that the internal elastic lamina plays a central role in the initiation of the inflammatory process. Fragmentation and disintegration of elastic fibers occur. This is closely associated with an accumulation of giant cells, which often seem to engulf parts of the internal elastic lamina.

The giant cells are difficult to find in some cases, and their absence does not exclude the diagnosis if other features are present. Fibrinoid necrosis is seen less commonly in necrotizing arteritis.

The more sections that are examined in the area of arteritis, the more likely it is that giant cells will be found. What is needed is transmural acute and chronic inflammation for acute diagnosis or evidence of previous repair. Healed or subacute phase shows fibrosis, fragmented internal elastic lamina, chronic inflammatory cells in the intima or media, and ideally neovascularization. Long breaks in internal elastic lamina favor healed arteritis over atherosclerosis.

Intimal proliferation is often marked. However, intimal proliferation is a nonspecific feature in the elderly, and does not suggest past or present arteritis if found alone.

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