title: Primary intra-axial leiomyosarcoma with obstructive hydrocephalus in a young dog.
abstract: A female Chihuahua dog aged 2 months had a 3-week history of progressive neurological signs (abnormal behaviour, disorientation, left-sided circling, and incessant whimpering). Necropsy revealed a primary leiomyosarcoma in the midline of the posterior thalamus with secondary obstructive hydrocephalus of the lateral ventricles. Grossly, an infiltrative, grey-white tumour had partly invaded the third ventricle. Histologically, the tumour formed hypercellular, interlacing bundles of neoplastic spindle cells with blunt-ended nuclei. Neoplastic cells were strongly immunoreactive for vimentin and both muscle-specific and alpha-smooth muscle actin; MIB-1 immunoreactivity indicated a proliferative index of up to 5%. Leiomyosarcoma should be included in the differential diagnosis for primary brain tumours and hydrocephalus in young dogs.
authors.affiliation: Pathology Service, Veterinary Medical Teaching Hospital (VMTH), School of Veterinary Medicine, University of California-Davis, Davis, CA 95616-8747, USA.
authors.forename: T S
authors.initials: TS
authors.lastname: Zabka
authors.forename: J A
authors.initials: JA
authors.lastname: Lavely
authors.forename: R J
authors.initials: RJ
authors.lastname: Higgins
mesh_terms: D000199:Actins / Q000032:analysis; D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis; D001932:Brain Neoplasms / Q000150:complications / Q000473:pathology / Q000662:veterinary*; D049109:Cell Proliferation; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D017809:Fatal Outcome; D005260:Female; D006849:Hydrocephalus / Q000209:etiology / Q000473:pathology / Q000662:veterinary*; D007890:Leiomyosarcoma / Q000150:complications / Q000473:pathology / Q000662:veterinary*; D013788:Thalamus / Q000737:chemistry / Q000473:pathology*; D014746:Vimentin / Q000032:analysis
chemical_list: D000199:Actins; D014408:Biomarkers, Tumor; D014746:Vimentin