title: Aggressive spindle cell rhabdomyosarcoma in an 11-month-old boxer dog.
abstract: Rhabdomyosarcoma (RMS) is a malignant neoplasm derived from mesenchymal tissue with a tendency toward myogenic differentiation associated with the embryogenesis of skeletal muscle. According to the histological features, it can be classified in embryonal, botryoid, alveolar, and pleomorphic, which usually correspond to clinical behavior and prognosis. The spindle cell (SCRMS) variant is a rare subtype of the embryonal RMS and is considered to be less aggressive lesion. The aim of the present paper is to report an unusual case of SCRMS in an 11-month-old male boxer dog diagnosed as extensive SCRMS that affected the frontal region of the skull. Due to the aggressive nature of the lesion and poor clinical prognosis the dog's owners preferred euthanasia as a treatment. A full postmortem examination was carried out. Microscopically, the lesion was composed of a highly cellular proliferation of spindle cells arranged in long and intersecting fascicles. After performing the immunohistochemical studies (HHF-35, smooth muscle actin, desmin and MyoD1), the present case was diagnosed as SCRMS.
authors.affiliation: School of Veterinary Medicine, Federal University of Goiás, Goiânia-GO, Brazil. marcelloroza@gmail.com
authors.forename: Marcello Rodrigues
authors.initials: MR
authors.lastname: da Roza
authors.forename: Rivadávio Fernandes Batista
authors.initials: RF
authors.lastname: de Amorim
authors.forename: Fabiana Pirani
authors.initials: FP
authors.lastname: Carneiro
authors.forename: Nara
authors.initials: N
authors.lastname: Benatto
authors.forename: Mauricio
authors.initials: M
authors.lastname: Barriviera
authors.forename: Márcia Cristina da Costa
authors.initials: MC
authors.lastname: Miguel
mesh_terms: D000818:Animals; D001344:Autopsy; D003893:Desmin / Q000032:analysis; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005065:Euthanasia; D008297:Male; D008437:Maxilla / Q000473:pathology; D018233:Rhabdomyosarcoma, Embryonal / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D012886:Skull / Q000473:pathology
chemical_list: D003893:Desmin