Fig. 1

Histology of the four DCT cases. Case 1 (a and b): a small arteries with organized thrombosis are occasionally observed (a). b The basilar artery showed no active inflammation and was dilated with irregular thickening of endothelial layer (arrow) and disruption of elastic layer. Case 2 (c and d): c the arteries showed still active inflammation with disruption of elastic layer (arrow) and thrombosis (star). f Infarction in basal ganglia. Case 3 (e and f): e larger meningeal arteries show often circumferential thickening of intima (arrow) and active inflammation in the media (arrow). f Many smaller arteries in the vicinity of the inflamed or destructed arteries show thrombosis with neutrophil infiltrates. Case 4 (g and h): g a severely inflamed artery with vascular destruction and obstruction in the meningeal pus pocket at the frontal lobe showing organization. h The basilar artery showed chronic active inflammation and dilatation with disruption of elastic layer (arrows), partially obstructed by thromboembolus (star) with leucocyte clearance. Similarly observed pathologies in non-DCT control meningitis cases (i and j): i active vascular inflammation of a meningeal artery with thickening of intima and inflammation of tunica media. j thrombosis of small parenchymal vessel