Clinical, cytological and histopathological evaluation of mammary masses in cats from Rio de Janeiro, Brazil

The vast majority of mammary tumors in cats are malignant with high metastatic and mortality rates. This study evaluated clinical, cytological and histopathological aspects of 20 cases of cat mammary masses deriving from the city of Rio de Janeiro. Data on history, macroscopic description, evidence of regional lymph node and distant metastases, clinical examination and treatment were collected. The cats were treated with unilateral mastectomy, unilateral mastectomy plus chemotherapy or chemotherapy alone. Tissues were submitted for cytological and histological evaluation. Histopathological analysis described one case of mammary hyperplasia and 19 cases of adenocarcinoma. Inadequate surgical margins were obtained in two cats while six showed evidence of microscopic invasion in other mammary glands. Multiple mammary involvement and greater tumor size (diameter over 7.05 cm) were correlated with increased chance of local metastases. Ulceration of tumors and metastases were common. These facts support the highly malignant nature of this neoplasia and emphasize the risks associated with delay in diagnosis and treatment of feline patients. In conclusion, mammary palpation should be performed routinely in the clinical practice.