INTRAVASCULAR MALIGNANT T-CELL LYMPHOMA (MALIGNANT ANGIOENDOTHELIOMATOSIS) IN A CAT

A 7-year-old spayed female Siamese cat was presented with a 7-day hist ory of ataxia, circling to the right, and involuntary micturition and defecation. Cerebrospinal fluid analysis showed increased protein cont ent and relative eosinophilia. At necropsy, there was flattening of th e cerebral cortical gyri of the right frontal and parietal lobes, and both kidneys had multiple wedge-shaped cortical indentations. Histolog ically, the cerebral cortex contained several extensive malacic foci, and the kidneys had multifocal parenchymal degeneration and atrophy. T here was multifocal partial to complete thrombosis of renal interlobar arteries and of the right middle cerebral artery and meningeal branch es; these thrombi contained large anaplastic round cells, which often invaded the arterial wall. Many smaller vessels within the kidneys and brain were occluded with clusters of similar cells, without thrombosi s or vascular wall invasion. The neoplastic round cells had immunohist ochemical staining properties of T lymphocytes.