title: Fibroma with osseous metaplasia of external auditory canal in a dog.
abstract: The present report describes a case of fibroma with osseous metaplasia of the external auditory canal in a 7-year-old male Pomeranian dog. Upon otoscopic examination, the right external auditory canal was almost completely obstructed by a well-circumscribed mass adjacent to the eardrum. The mass was surgically excised. Grossly, it was well demarcated, firm when cut, pink, and measured 0.3 cm x 0.2 cm x 0.7 cm. The cut surface of the mass exhibited a central portion of homogeneously white osseous components surrounded by brown to pink soft tissue. Microscopically, the resected external auditory canal mass mainly consisted of fibroblastic spindle cells showing differentiation to metaplastic osteoblast-like cells. Metaplastic osteoblasts and osteoclasts lining the osteoid bony trabeculae were also observed. Bony trabeculae and spicules were separated by abundant collagen and neoplastic fibroblastic cells. Fibromatous components, irregular formation of woven bone spicules, and the presence of osteoblasts lining bony trabeculae led to a diagnosis of fibroma with osseous metaplasia.
authors.affiliation: College of Veterinary Medicine, Kyungpook National University, Daegu City 702-701, Republic of Korea.
authors.forename: Jin-Kyu
authors.initials: JK
authors.lastname: Park
authors.forename: Seung-Keun
authors.initials: SK
authors.lastname: Lee
authors.forename: Sang-Joon
authors.initials: SJ
authors.lastname: Park
authors.forename: Il-Hwa
authors.initials: IH
authors.lastname: Hong
authors.forename: Kyu-Shik
authors.initials: KS
authors.lastname: Jeong
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000473:pathology; D004283:Dog Diseases / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D004285:Dogs; D004424:Ear Canal / Q000473:pathology*; D004428:Ear Neoplasms / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D005350:Fibroma / Q000662:veterinary*; D008297:Male; D008679:Metaplasia / Q000175:diagnosis / Q000473:pathology / Q000601:surgery / Q000662:veterinary