title: Disseminated pleomorphic myofibrosarcoma in a grizzly bear (Ursus arctos horribilis).
abstract: The pathological and diagnostic features of a widely disseminated pleomorphic high-grade myofibroblastic sarcoma are described in a 23-year-old male brown bear (Ursus arctos horribilis). Firm, solid, white to tan neoplastic nodules, often with cavitated or soft grey-red necrotic centres, were observed throughout most internal organs, subcutaneous tissues and skeletal muscles on gross examination. Microscopically, the tumour consisted of pleomorphic spindle cells forming interlacing fascicles with a focal storiform pattern with large numbers of bizarre polygonal multinucleate cells, frequently within a collagenous stroma. Immunohistochemistry, Masson's trichrome stain and transmission electron microscopy designated the myofibroblast as the cell of origin. This is the first case of a high-grade myofibrosarcoma in a grizzly bear.
authors.affiliation: California Animal Health and Food Safety Laboratory, University of California, W Health Sciences Dr, Davis, CA, USA. amete@ucdavis.edu
authors.forename: A
authors.initials: A
authors.lastname: Mete
authors.forename: L
authors.initials: L
authors.lastname: Woods
authors.forename: D
authors.initials: D
authors.lastname: Famini
authors.forename: M
authors.initials: M
authors.lastname: Anderson
mesh_terms: D000008:Abdominal Neoplasms / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D017809:Fatal Outcome; D005354:Fibrosarcoma / Q000473:pathology / Q000662:veterinary*; D018219:Histiocytoma, Benign Fibrous; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D018482:Muscle, Skeletal / Q000473:pathology; D058628:Myofibroblasts / Q000648:ultrastructure; D009217:Myosarcoma / Q000473:pathology / Q000662:veterinary*; D012983:Soft Tissue Neoplasms / Q000473:pathology / Q000662:veterinary*; D001503:Ursidae