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Equine Protozoal Myeloencephalitis (view source)
Revision as of 22:32, 8 July 2010
, 22:32, 8 July 2010→Pathology
====Biopsy====
====Biopsy====
====Pathology====
====Pathology====
CNS lesions in the horse often extesnive. Mutlifocal areas of H+ to light discoloration of brain or spinal cord may be visble on gross exam. Lesions may be microscopic to several cm wide. Brasintem and spinal cord affected most often but lesions have been seen in perpheral nerves. Microscopically lesions are focal to diffuse areas of nonsuppurative inflammation and necrosis with perivascualr infiltration of mononclear cells, including lymphocuytes, macs and plasma cells. Giant cells, eosinphils and gitter cells are also present in inflamatory infiltrates. Grey or white matter or both affected. organsisms have been ofund in neurons, leukocytes and vascualr endothelium, but tend to devlop most often in neurons.
Lesions: There is focal discoloration, hemorrhage, and/or malacia of CNS tissue. Histologically, protozoa are found in association with a mixed inflammatory cellular response and neuronal destruction. Schizonts, in various stages of maturation, or free merozoites commonly are seen in the cytoplasm of neurons or mononuclear phagocytes. Also parasitized are intravascular and tissue neutrophils and eosinophils and, more rarely, capillary endothelial cells and myelinated axons. Merozoites may be found extracellularly, especially in areas of necrosis. In at least 75% of cases, protozoa are not seen on H&E-stained sections, and the diagnosis is made on the basis of characteristic focal or multifocal inflammatory change.
Lesions: There is focal discoloration, hemorrhage, and/or malacia of CNS tissue. Histologically, protozoa are found in association with a mixed inflammatory cellular response and neuronal destruction. Schizonts, in various stages of maturation, or free merozoites commonly are seen in the cytoplasm of neurons or mononuclear phagocytes. Also parasitized are intravascular and tissue neutrophils and eosinophils and, more rarely, capillary endothelial cells and myelinated axons. Merozoites may be found extracellularly, especially in areas of necrosis. In at least 75% of cases, protozoa are not seen on H&E-stained sections, and the diagnosis is made on the basis of characteristic focal or multifocal inflammatory change.