Metastatic epithelioid mesothelioma in a dog

Resumen

Mesothelioma is a neoplasm considered infrequent in canines. Its peritoneal location is not common in dogs when compared to the pleural origin. This study aims to report a case of metastatic trabecular epithelioid mesothelioma in a dog, diagnosed through anatomopathological and immunohistochemical examination. The patient was hospitalized and treated, but his clinical picture worsened, and euthanasia was chosen. At necropsy, the main findings were the abdomen and thorax with the presence of tumor nodules of soft consistency, and the cuts were pinkish-brown in color. Histologically, they were composed of malignant mesothelial cells, predominantly epithelioid cells arranged in cords. There was metastasis in the lungs, kidneys, and lymphatic vessels of the heart. Samples were submitted to immunohistochemical analysis and tumor cells showed cytoplasmic immunoreaction for anti-human mesothelial cell (HBME-1) and anti-cytokeratin (AE1/AE3), in addition to a moderate proliferative index evidenced by the reaction against the proliferation nuclear antigen cellular (PCNA). There was no staining for vimentin and anti-epithelial antigen (EMA). Thus, the anatomopathological and immunohistochemical analysis showed that it was a trabecular epithelioid mesothelioma with a moderate proliferative index and multiple metastatic sites.