Table 5.

Main histopathological findings from biopsy and postmortem brain tissue samples. PubMed research ranged from January 2016 to May 2021

Study	Histological findings on biopsy and postmortem tissue
Wang et al. [42]	Brain tissue edema Degeneration Necrosis Glial cell hyperplasia Tissue cell response Scattered lymphocytic infiltration Vascular wall thickening Intra-vascular and perivascular lymphocytes Few granulocytes
Sundaram et al. [43]	Lymphocytic, necrotizing, and granulomatous patterns
Suthiphosuwan et al. [56]	Vasculocentric trans-mural lymphocytic infiltration CD20 + (B-cell lymphocytes), CD3 + (T-cell lymphocytes) Macrophages (CD163 +)
Caputi et al. [44]	Angiocentric trans-mural lymphocytic infiltration CD3 +
Salvarani et al. [45]	Granulomatous inflammatory pattern with deposits of β-amyloid peptide A granulomatous and necrotizing pattern Acute necrotizing pattern Lymphocytic pattern
Chang et al. [6••]	Demyelination Lymphocytic vasculitis Necrotic vasculitis with inflammation and fibrinoid necrosis Granulomatous vasculitis (granuloma with lymphocytes and macrophages)
Takatsu et al. [46]	Vasculitis with fibrinoid necrosis
Denny et al. [47]	Chronic inflammatory infiltrate with CD3-positive T cells including both CD4 + and CD8 + and CD20 + (B cells), and macrophages (CD68 +)
Wilson et al. [48]	Perivascular and intramural chronic inflammation with stenosis of the lumen
Spence et al. [49]	Mural thickening with diffuse lymphocytic infiltration with fibrinoid necrosis
Benson et al. [50]	Transmural lymphocytic infiltration
Han et al. [51]	Inflammatory infiltration and granulomas
Van Rooij et al. [52•]	Thickening of the tunica intima with inflammatory cells in the tunica media