Multilobular tumor of bone in a dog

Multilobular tumor of bone in a dog
Judith Akins, DVM, MS

Tissue from a mass on the dorsal head of a twelve-year-old spayed female, mixed breed dog was submitted to the histopathology section at the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) for examination. The mass on the head was noticed by the owner approximately two months before removal and it had grown noticeably during that time. A radiograph of the skull showed the mass was attached to the skull. There was no evidence of metastasis on a radiograph of the lungs.  The histopathology showed the mass was composed of multiple lobules of cartilage separated by thin bands of collagen. The centers of the lobules often are mineralized. There were no mitotic figures seen in multiple high-power fields. The diagnosis was multilobular tumor of bone.

Multilobular tumor of bone (other past terms include chondroma rodens, calcifying aponeurotic fibroma, multilobular chondroma or osteoma) is a slow growing mesenchymal cell tumor that most typically occurs in the skull of dogs with reported growth also in the maxillae and mandible. It has also been reported occasionally in cats and horses. This tumor is more typically benign but does have the potential to become malignant. Even if metastasis does not occur, continued growth may be destructive or impair the function of adjacent structures. Complete excision is the treatment of choice. Re-growth of the mass is likely following incomplete excision.

For more information about this case, contact Dr. Judith Akins, anatomic pathologist at the College Station laboratory. To learn more about TVMDL’s test offerings, visit tvmdl.tamu.edu or call one of the agency’s full-service laboratories.

Reference
Thompson, K.G. and Dittmer, K.E. In: Donald Meuten, ed. Tumors in Domestic Animals, 5^th ed. Ames, IA: John Wiley & Sons, 2017. pp. 409-411.