From Dog
Osteoma showing proliferation of trabeculae of mature bone[1]

Osteoma are a rare, benign inflammatory tumor of canine bone.

These tumors, which commonly affect the flat bones of the canine skull[2], facial bones, tongue[3] and skin (multifocal osteoma cutis)[4].

Osteomas are protruding tumor masses composed of abnormally dense, but otherwise normal bone formed in the periosteum[5]. They may resemble exostoses in structure and frequently cannot be differentiated from them on histopathologic examination. Multilobular osteoma (chondroma rodens) has also been reported[6].

Osteomas frequently protrude from the underlying bony surface. The excised tumor is extremely hard, with a smooth surface that is covered by a zone of connective tissue.

These slowly growing tumors will cause clinical signs only when they impinge on adjacent structures.

Diagnosis is based on clinical presentation with supportive radiography which often displays bony protruberance over normal bone.

Radiographs are necessary to determine possible secondary metastases.

Diagnosis usually requires histopathological examination of bone biopsy. These tumors have a characteristic appearance, with wide trabeculae of mature bone in an irregular pattern. These trabeculae may be lined by mature osteoblasts[7].

A differential diagnosis would include myxosarcoma[8], giant cell tumor, bone cyst, fibrosarcoma, osteochondroma, chondrosarcoma, polyostotic lymphoma and Spirocerca lupi.

Treatment usually involves wide-margin surgical resection, or use of long-term non-steoridal anti-inflammatory drugs[9]. In cranial osteomas, cranioplasty is usually required with use of a preformed molded polymethylmethacrylate implant[10].

The prognosis is usually good following crudescence of the tumor.


  1. Uni of Pennsylvania
  2. Johnson KA et al (1996) Zygomatic osteoma with atypical heterogeneity in a dog. J Comp Pathol 114(2):199-203
  3. Fernandez M et al (2012) Lingual osteoma in a dog. J Small Anim Pract 53(8):480-482
  4. Martin DM et al (2006) Multifocal osteoma cutis in a golden retriever. Can Vet J 47(4):360-362
  5. 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
  6. Fukui K & Takamori Y (1986) Multilobular osteoma (chondroma rodens) in a pekingese. Vet Rec 118(17):483
  7. Foley RH (1978) Osteoma in two young dogs. J Am Anim Hosp Assoc 14:253
  8. Khachatryan AR et al (2009) What is your diagnosis? Vertebral mass in a dog. Vet Clin Pathol 38(2):257-260
  9. Grozdanic S et al (2012) Successful medical treatment of an orbital osteoma in a dog. Vet Ophthalmol May 25
  10. Bryant KJ et al (2003) Cranioplasty by means of molded polymethylmethacrylate prosthetic reconstruction after radical excision of neoplasms of the skull in two dogs. J Am Vet Med Assoc 223(1):67-72