histopathological and radiological diagnosis of canine malignant mixed mammary tumor: case report and literature review

A canine malignant mixed mammary tumor is an uncommon neoplasm of the mammary gland consisting of both carcinoma and sarcoma characteristics (carcinosarcoma). it can be a life-threatening disease by metastasis to regional lymph nodes and lungs. in this study, a case report of a dog with a malignant mixed mammary tumor was diagnosed by histopathological and radiological assessments. a 10-year-old female dog with multiple masses in the abdominal area near to mammary glands was referred to a clinic. the tumors were surgically removed, but after some time there was a recurrence. diagnostic imaging showed multiple superficial homogeneous hypoechoic mass lesions without vasculature in the abdominal wall near to mammary glands. these masses were surgically removed and samples of them were fixed in 10% neutral buffered formalin for microscopic examination. histopathological examination of masses revealed tumor cells with a solid pattern, cellular and nuclear pleomorphism, prominent nucleoli of neoplastic cells, mitosis, extracellular myxoid matrix, differentiated chondroid/osteoid, fibroplasia, necrosis, and hemorrhage. acidophilic cytoplasm of some polyhedral tumor cells with vesicular nuclei similar to epithelial cells were seen and neoplastic cells with scant cytoplasm, and elongated nuclei with pale nucleoli resembling mesenchymal cells were also observed. based on histopathological findings, the disease was diagnosed as a malignant mixed mammary tumor with well-differentiated characteristics. although mixed mammary gland tumors are common neoplasms in female dogs, they have the potential to become malignant. this transformation to malignancy is influenced by factors that are still poorly understood. considering predictive factors for clinical outcome is possible by investigating lymph node metastasis that is related to shorter survival time and death. despite all these considerations, the best approach to deal with such diseases is early prognosis so that better management plans can be implemented.