Giant cell tumor

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Giant cell tumor of a dog bone[1]

Canine giant cell tumors (Osteoclastoma) are a rare benign tumor of bones[2].

These tumors usually present as mono-ostotic nodular masses arising from the distal metaphysis and epiphysis of long bones and arise from mesenchymal cells that differentiate into fibroblast-like stromal component and multinucleated cells resembling osteoclasts.

Lameness is a common presenting feature and obvious swelling is usually noticeable in the affected area[3].

Radiographic findings usually reveal osteolysis with little evidence of metastases in other organs.

These tumors should be distinguished histologically from osteosarcomas which may contain numerous giant cells. However, within the giant cell tumors little or no matrix will be produced[4]. Osteoclastomas appear as highly vascularized stroma with extensive proliferation of ovoid-shaped cells regularly interspersed with giant cells.

A similar non-pathogenic bone disease has been noted in flat bones, referred to as giant cell reparative bone granuloma. This disease, which is usually an incidental findings in some dogs, originates preferentially in flat bones on the skull and mandible as a result of trauma-associated intraosseous hemorrhage, with new bone formation and sclerosis[5].

Treatment of giant cell tumors usually requires surgical excision of the affected bone. If the tumor involves a large portion of the femur/tibia or radius/ulna, ostectomy or amputation may be required.


  1. University of Pennsylvania
  2. Garman RH et al (1977)
  3. Berg J et al (1990) Giant cell tumor of the accessory carpal bone in a dog. J Am Vet Med Assoc 197(7):883-885
  4. Garman RH et al (1977) Malignant giant cell tumor in a dog. J Am Vet Med Assoc 171:546
  5. Trigo FJ et al (1983) A comparison of canine giant cell tumor and giant cell reparative granuloma of bone. Vet Pathol 20(2):215-222