HISTOLOGICAL AND IMMUNOHISTOCHEMICAL FEATURES OF A PLURIVISCERAL METASTATIC MAMMARY CARCINOSARCOMA IN A DOG

A case of mammary carcinosarcoma is reported in a 11-year-old, Terrier crossbreed dog, which was mastectomy operation had been performed 2 years ago. The patient presented extensive and coalescent nodules in all MG. ThoracicX-ray was performed and multiple opaque areas was seen in the lung. The patient's health condition deteriorated despite all medical supports. As a result of this the patient was euthanized. Microscopically, the neoplasm had infiltrative growth with a solid pattern and was composed of a cell population. There were also neoplastic areas with a myxoide matrix differentiated chondroid, osteoid, or adipose tissue. The mammary masses showed strongly and diffusely positive immunolabeling for anti-cytokeratin and anti-vimentin. All the metastatic lesions that mesenchimal component predominates were positive for vimentin. As opposed to the no cytokeratin-positive cells were observed in this areas. These findings were considered compatible with metastatic osteosarcomatous component of a primary mammary tumor. Carcinosarcoma of the MG is a biphasic and its nature must be confirmed using immunohistochemistry. Metaplastic changes may have malignant potential but should not be considered as malignant lesions. The most significant histopathological parameter is the identification of transitional zones between the epithelial and mesenchymal cells. Primary carcinosarcoma of the MG is a rare tumor with aggressive biological behavior and sarcomatous component of this present tumor has a high metastatic potential. The patients should be closely monitored due to the unknown or unpredictable biological behavior of this tumor.