What are the histologic features of suggestive of Takayasu arteritis in the vasoocclusive stage?

Updated: Nov 14, 2018
  • Author: Jefferson R Roberts, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

In the vasoocclusive stage, the lesions are characterized by occlusion and signs of ischemia. The adventitia and media are replaced by fibrous scarring, the vasa vasorum are obliterated, and the intima undergoes irregular thickening. Medial degeneration, disruption of the elastic lamellae, and thrombosis can occur. Aneurysms can form, but no aneurysms attributed to Takayasu arteritis have been identified in the intracranial circulation. The literature reports a few cases of intracranial aneurysms that are considered to be incidental.

The ground substance in the intima is increased markedly, histochemically showing a basophilic acid mucopolysaccharide in a state of gelatinous swelling.

An increase in CD4 and decrease in CD8 lymphocytes, along with reduced B lymphocytes, have suggested a defect in T-cell regulation (cell-mediated immunity). Biopsy samples exhibit infiltrates of lymphocytes and monocytes in both the vessel walls and a peripheral nerve vasculitis. Lymphocytes and monocytes are attracted to the vessel wall either by an infectious agent or an autoimmune response, modulated by intercellular adhesion molecules (ICAMs).


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