Fig. 2

Acute endotheliitis. (A) In midbrain tegmentum, a thin-walled microcirculatory channel has many karyorrhectic PMNs including some fragmenting into dot-like nuclear dust (Case 10). (B) Similar finding as in (A) is seen here in subarachnoidal microvessels between folia of the cerebellar superior vermis (Case 10). (C) Small microcirculatory channel with mural collagenosis in medial temporal subependymal white matter has intraluminal karyorrhectic PMNs and mononuclear cells (Case 14). (D) In lateral temporal white matter, a dilated thin-walled microvessel is filled with PMNs, many with karyorrhexis, and mononuclear cells. There is scattered ‘nuclear dust’ (black arrow) and a few karyorrhectic PMNs appear to be transmigrating into fibrous adventitia (white arrow) (Case 14). (E) Mixture of karyorrhectic PMNs, some ‘nuclear dust’, and many mononuclear cells in very dilated microvessel in internal capsule near hypothalamus (Case 23). (F) Pyknotic and karyorrhectic PMNs arrayed along luminal border of microvessel in lateral hypothalamus (Case 34). Scale bars: 10 μm in (A–C, E and F); 20 μm in (D)