Immunohistochemical and Histopathological Findings of Chondrosarcoma in Mammary Gland of A Dog: A Case Report

Chondrosarcoma is a malignant tumor of chondrocytes and occurs most commonly on the flat bones and the nasal cavity. Mammary chondrosarcoma is an uncommon tumor in canine practice. The aim of present paper is to report a case of mammary chondrosarcom in a 10-year-old German shepherd bitch. The dog with a mass in her right caudal thoracic mammary gland which grown gradually in 8 months, was referred to the veterinary teaching hospital. The mass and local lymph nodes were resected by complete mastectomy and were sent to department of veterinary pathology for histopathological examination. Macroscopically, the mass was fluctuant containing firm mases in it, totally measuring 5x4x5 cm in diameter. The cross section was yellow and there were many cavernous structures which were filled with grayish fluid. Microscopic examination revealed a mass of large mature cartilage structures with lacunae and chondrocytes and chondroblastes with new forming structures of cartilage. Immonohistochemical investigation revealed that the tumor is negative for Estrogen receptor (ER) expression. According to macroscopic and microscopic investigations chondrosarcoma was diagnosed.