Encephalic meningioangiomatosis in a cat

Abstract

Meningioangiomatosis (MA) is a rare proliferative meningovascular entity that has been described mainly in humans and dogs. Here we describe MA in a 13-y-old spayed female domestic shorthaired cat that died 5 d after acute change in behavior, open-mouth breathing, seizures, hyperthermia, and inability to walk. On MRI, the lesion appeared predominantly as extraparenchymal hemorrhage. Autopsy changes consisted of a dark-red, hemorrhagic plaque that expanded the leptomeninges and outer neuroparenchyma of the right piriform and temporal telencephalic lobes, chalky white nodules in the peripancreatic fat, and yellow fluid in the abdomen. Histologically, the lesion in the brain consisted of leptomeningeal thickening by spindle cells that effaced the subarachnoid spaces and extended perivascularly into the underlying cerebral cortex. Spindle cells were arranged as streams or whorls around blood vessels, and had slender eosinophilic cytoplasm and elongated nuclei with coarsely stippled chromatin and 1 or 2 distinct nucleoli. There was extensive hemorrhage, clusters of hemosiderin-laden macrophages, and mineralization throughout. Spindle cells had positive immunolabeling for vimentin. A striking MRI and gross feature in our case was the extensive hemorrhage associated with the MA lesion. Additional findings included suppurative pancreatitis with peritonitis and supraspinatus myonecrosis.

Keywords: cats; meningeal proliferation; meningioangiomatosis; neurology; neuropathology.

Figures 1–3.

Encephalic meningioangiomatosis in a cat. Figure 1. Transverse MRI of the head at the level of the piriform lobes of the cerebrum. On T2-weighted (1a) and T2-weighted fluid attenuated inversion recovery image (1b), there is a right-sided, extraparenchymal, plaque-like hypointense lesion (arrow) overlying the temporal lobe. The internal capsule and corona radiata are T2-hyperintense (asterisk), consistent with vasogenic edema. On T1-weighted images (1c), the lesion is heterogeneously iso- to hypointense with focal regions of hyperintensity (arrowhead). Following contrast administration (1d), ill-defined, regions of focal contrast enhancement in the parenchyma surround the plaque-like lesion (arrowhead). Figure 2. A poorly demarcated, dark red area of hemorrhage (asterisk) affects the right temporal and part of the right occipital lobe of the telencephalon. Figure 3. A coronal section of the brain at the level of the thalamus reveals a dark red plaque (arrowhead) that expands the leptomeninges and involves the outer cerebral cortex.

Figures 4–7.

Encephalic meningioangiomatosis in a cat. Figure 4. Extensive leptomeningeal thickening by proliferated spindle cells with extensive hemorrhage. The lesions expand and efface the subarachnoid spaces and extend into the underlying cerebral cortex. H&E. Figure 5. Streams and perivascular clusters of spindle cells expand and efface the leptomeninges (top) and cerebral cortex (bottom). H&E. Figure 6. Spindle cells in the outer cerebral cortex are interspersed with remnants of gray matter. H&E. Figure 7. Spindle cells have slender eosinophilic cytoplasm with indistinct cell margins and elongated nuclei with coarsely stippled chromatin. H&E.