MACROSCOPIC APPEARANCES

Arthrogryposis, pterygia, muscular hypoplasia, and pulmonary hypoplasia are found at necropsy (Fig. 7.1a). Bubble-like hemispheres that are macroscopically indistinguishable from those seen in encephaloclastic hydranencephaly have a diaphanous pallium studded with calcifications (Fig. 7.1b).

MICROSCOPIC APPEARANCES

The thin, disorganized pallium has a narrow immature cortical plate. Glomeruloid endothelial vasculopathy, which is unique to this disorder, is prominent throughout the CNS (Fig. 7.2). Endothelial cells in the glomeruloid structures have PAS-positive intracytoplasmic inclusions, which appear on electron microscopy as homogeneous granular material surrounded by rough endoplasmic reticulum (Fig. 7.3).

MACROSCOPIC APPEARANCES

Potter’s facies, contraction deformities of the limbs, pulmonary hypoplasia, and bilateral renal agenesis are found at necropsy, but there are no cutaneous vascular nevi.

The leptomeninges are extremely vascular, and in some cases there is subarachnoid hemorrhage. The circle of Willis is normal. The brain is small and gyral atrophy is evident. In the cerebrum, there is cortical and white matter necrosis, with or without hemorrhage and calcification.

MICROSCOPIC APPEARANCES

There is diffuse angiodysplasia, consisting of ectatic capillaries and veins. These are present in the leptomeninges, cerebral cortex, cerebellum, and brain stem. The angiodysplasia is complicated by thrombosis, infarction, hemorrhage, hemosiderin-laden macrophages, gliosis and calcification in the cerebral cortex and white matter (Fig. 7.4).

MACROSCOPIC AND MICROSCOPIC APPEARANCES

The vascular malformation is fed by one or both of the posterior cerebral arteries or their branches resulting in dilatation of the vein of Galen and enlargement of the cerebral venous system and sinuses (Fig. 7.5). The enlarging vascular mass may compress the aqueduct causing hydrocephalus, or may undergo calcification or thrombosis. Microscopically, veins show the typical changes of ‘arterialization’, e.g. hyperplasia and hypertrophy of the intima and muscularis, that result from increased intraluminal pressure.

MACROSCOPIC AND MICROSCOPIC APPEARANCES

Lymphocytic infiltration of the media and destruction of the elastica of affected vessels are associated with giant cells and followed by fibrosis and thickening. The blood vessels are further narrowed by superimposed intimal proliferation and atheroma. Thromboembolic disease leads to cerebral ischemia. Only rarely does the arteritic process directly involve cerebral vessels (Fig. 7.6).

MACROSCOPIC AND MICROSCOPIC APPEARANCES

In fatal cases, there is coronary arteritis with thrombosis and aneurysm formation, interstitial myocarditis, and myocardial infarction. Various medium-sized arteries can be involved, including cerebral vessels (Fig. 7.7).

MACROSCOPIC AND MICROSCOPIC APPEARANCES

Hyaline eosinophilic platelet thrombi occlude small arteries and arterioles, which also show striking endothelial swelling. Multiple microinfarcts are present in cerebral and cerebellar gray matter (Fig. 7.8).