Frontal chondrosarcoma in a cat.

In this case, chondrosarcoma, detected on the frontal bone of a 12-year-old female cross-bred cat was examined clinically and histopathologically. After being processed routinely, specimens were stained with Hematoxylin & Eosin and Crossman Modification of Mallars Triple Stain. The neoplasm was composed of numerous fusiform mesenchymal cells intimately associated with the formation of lobular structure, separated by thin fibrous septae. In the center there were observed atypical chondrocytes, forming the matrix of the tumoral mass, surrounded by round-ovoid, fusiform mesenchymal cells having interference with the septal tissue at the periphery. Few mitotic figures were detected in these areas. The tumors pattern, localization, the species and the age of the animal were consistent with those of multilobular chondroma known as chondroma rodens. Although the mitotic figures and the wide atypia indicated that the entity was a neoplasm of malign type, it was more likely considered to be the malign transformation of chondroma rodens. The post-surgical outcome of the patient was observed, and recurrence on the same site was reported within 2 months.