Giant cell arteritis (GCA) / temporal arteritis
Both terms can be used interchangeably.
GCA is a serious form of vasculitis which typically affects the temporal arteries.
Tunica Intima
Comprises a single layer of endothelial cells supported by a basement membrane.
Internal elastic lamina
Distinguishes the boundary between the intima and media
Tunica media
Composed of smooth muscle cells
Adventitia
Merges with the surrounding collagenous tissue. Contains the vasa vasorum ‘vessels of vessels’ which are a capillary network that supply oxygen and nutrients to the artery.
Granuloma
Collections of mononuclear cells (lymphocytes and macrophages, with or without the formation of giant cells.
Multinucleated giant cells
refer to large cells with multiple nuclei.
Panarteritic pattern GCA
This term is used when inflammatory cells are seen distributed in all layers of the arterial wall.
Concentric bilayer pattern GCA
This term is used when inflammatory cells are present in the adventitia and the tunica intima. Crucially, there is no infiltration of inflammatory cells into the tunica media.
Adventitial invasive pattern GCA
This term is used when inflammatory cells are present in the adventitia with focal extension into the tunica media.
The integrity of the tunica intima remains intact with no inflammatory cells present in this layer.
Adventitial pattern GCA
This term is used when inflammatory cells are restricted to the adventitia only.
Neoangiogenesis
The formation of new capillaries.
Periarteriolar lymphocytic infiltrate
This term is used when small focus of lymphocytes are seen in the distant connective tissues or around small vessels of distant connective tissues.
