What is your diagnosis? Intracranial mass in a cat

Abstract

A 14-year-old female spayed cat was presented with a 3-4-month history of circling to the left and intermittent head pressing. Neurologic examination findings localized the lesion to the left supratentorial region. Using magnetic resonance imaging, an extra-axial mass was found on the dorsal aspect of the brain at the level of the frontal and parietal lobes, compressing and displacing the brain ventrally and caudally. Craniectomy was performed and the mass was submitted for cytologic and histopathologic evaluation. Impression smears revealed abundant cholesterol crystals and loose clusters of mildly pleomorphic spindle cells, compatible with a meningioma. The histopathologic diagnosis was meningioma with psammoma bodies and numerous cholesterol clefts. Abundant cholesterol crystals within meningiomas in cats may present a diagnostic challenge when nucleated cells are scant. Other differential diagnoses for abundant cholesterol crystals in an intracranial mass include cholesterol granulomas and keratinizing cysts.

Coextensive Meningioma and Cholesterol Granuloma in the Forebrain of a Cat

“…Rarely, solitary cholesterol granuloma formation occurs in the brain of cats . Cholesterol cleft formation occurs as a pathologic change within some meningiomas . However, the extensiveness of cholesterol granuloma formation in this cat was considered noteworthy.…”

“…Another hypothesis is chronic deposition of cholesterol crystals as a result of localized chronic inflammation or hemorrhage, cysts, and neoplasms. Erythrocyte and other cellular membrane breakdown could result in accumulation of cholesterol crystals that elicit a foreign body granulomatous reaction . Cholesterol crystals might develop as a degenerative/senile change within the choroid plexus presumably from prior hemorrhage…”