From Dog
Osteochondroma in the central hard palate of a dog[1]
Multilobular osteochondroma of the canine skull[2]

Multilobular osteochondroma are a rare, invasive tumor of skeletal cartilage and bone affecting appendicular bone, vertebrae, trachea[3] and skull[4].

These tumors, which commonly affect the flat bones of the canine skull, are slow growing, locally invasive, and have the potential to metastasize to distant sites, particularly the lungs[5].

The tumor most commonly affects middle-aged to older, medium- to large-breed dogs and has no apparent sex or breed predisposition. The tumor may be either solitary, a monostotic osteochondroma, or multilobular, polyostotic osteochondromas (osteochondromatosis) or multiple cartilaginous exostosis.

Polyostotic osteochondromas are a heritable entity in dogs[6].

Clinically affected dogs usually present with multiple soft-tissue masses in the affected area with regional swelling and pain. Symptoms are associated with compression and distortion of adjacent structures. Vertebral osteochondromas usually result in spinal compression with hemiparesis or ataxia[7][8]. When the CNS is involved, seizures are a common presenting sign.

Diagnosis is based on clinical presentation with supportive radiography which often displays osteolyis of neighboring bone and osteolytic regions associated with the tumor. The tumors usually appear smoothly contoured, nodular subperiosteal masses of dense fibrocartilaginous and osseous tissue[9].

Pulmonary radiographs are necessary to determine possible secondary metastases. CT scans will assist in the assessment of any intracranial metastases.

A definitive diagnosis requires histopathology.

A differential diagnosis would include myxosarcoma[10], giant cell tumor, osteoma, osteosarcoma, chondrosarcoma, polyostotic lymphoma and Spirocerca lupi.

Treatment usually involves wide-margin surgical resection. In cranial masses, cranioplasty is often required, using polypropylene mesh and polymethyl methacrylate[11].

Adjuvant therapy including radiation treatment and chemotherapy has been reported, but little is known with respect to its effect on local recurrence, metastasis, and survival time[12].


  1. Dicks N & Boston S (2010) The use of an angularis oris axial pattern flap in a dog after resection of a multilobular osteochondroma of the hard palate. Can Vet J 51(11):1274-1278
  2. Kosvi.com
  3. Beck JA et al (1999) Surgical management of osteochondromatosis affecting the vertebrae and trachea in an Alaskan Malamute. Aust Vet J 77(1):21-23
  4. Green EM et al (1999) Malignant transformation of solitary spinal osteochondroma in two mature dogs. Vet Radiol Ultrasound 40(6):634-637
  5. Goldschmidt MH & Thrall DE (1985) Benign bone tumors in the dog. In: Newton CD, Nunamaker DM, editors. Textbook of Small Animal Orthopedics. Philadelphia: JB Lippincott. pp:899–907
  6. Pool RR (1978) Tumors of bone and cartilage. In Moulton J (ed): Tumors in Domestic Animals, 2nd ed. Berkeley, University of California Press. pp:89-149
  7. Ness MG (1993) Osteochondroma causing progressive posterior paresis in a lakeland terrier puppy. Vet Rec 132(24):608-609
  8. Caporn TM & Read RA (1996) Osteochondromatosis of the cervical spine causing compressive myelopathy in a dog. J Small Anim Pract 37(3):133-137
  9. Mozos E et al (2002) A newly recognized pattern of canine osteochondromatosis. Vet Radiol Ultrasound 43(2):132-137
  10. Khachatryan AR et al (2009) What is your diagnosis? Vertebral mass in a dog. Vet Clin Pathol 38(2):257-260
  11. Mouatt JG (2002) Acrylic cranioplasty and axial pattern flap following calvarial and cerebral mass excision in a dog. Aust Vet J 80(4):211-215
  12. Dernell WS et al (1998) Multilobular osteochondrosarcoma in 39 Dogs: 1979–1993. J Am Anim Hosp Assoc 34:11–18