Zygomatic Arch Parosteal Osteosarcoma in Dogs and a Cat

Vet Pathol. 2019 Mar;56(2):274-276. doi: 10.1177/0300985818798110. Epub 2018 Sep 24.


Parosteal osteosarcoma is a rare, slow-growing tumor most commonly arising from the surface of long bones. Tissue or histological sections from 5 dogs and 1 cat with zygomatic arch masses were examined. Clinical presentations varied from chronic sneezing to facial swelling. Imaging consistently demonstrated osseous proliferation in the area of the zygomatic arch. Histologically, the masses were characterized by well-differentiated fibro-osseous and chondroid components that radiated outward from the periosteum of the zygomatic bone. Cellular atypia and mitotic figures were uncommon. Parosteal osteosarcomas have previously been reported in the skulls of dogs and cats, but only 1 has been reported on the zygomatic arch. Initially, these tumors are of low histologic low grade, but with time, they can show more aggressive behavior and invade the underlying bone.

Keywords: cat; dog; maxilla; neoplasia; osteosarcoma; parosteal; zygomatic arch.

MeSH terms

  • Animals
  • Bone Neoplasms / diagnosis
  • Bone Neoplasms / diagnostic imaging
  • Bone Neoplasms / pathology
  • Bone Neoplasms / veterinary*
  • Cat Diseases / diagnosis
  • Cat Diseases / diagnostic imaging
  • Cat Diseases / pathology*
  • Cats
  • Dog Diseases / diagnosis
  • Dog Diseases / diagnostic imaging
  • Dog Diseases / pathology*
  • Dogs
  • Female
  • Male
  • Osteosarcoma / diagnosis
  • Osteosarcoma / diagnostic imaging
  • Osteosarcoma / pathology
  • Osteosarcoma / veterinary*
  • Tomography, X-Ray Computed / veterinary
  • Zygoma* / diagnostic imaging
  • Zygoma* / pathology