Metastatic epithelioid mesothelioma in a dog.

Mesotelioma epitelioide metastático em um cão. (Portuguese)

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 [ABSTRACT FROM AUTHOR]

Mesotelioma é uma neoplasia considerada infrequente em caninos. A sua localização peritoneal não é comum em cães quando comparada à origem pleural. Este estudo objetiva relatar um caso de mesotelioma epitelioide trabecular metastático em um cão, diagnosticado através de exame anatomopatológico e imuno-histoquímico. O paciente foi hospitalizado e tratado, mas apresentou piora do quadro clínico, optando-se pela eutanásia. Na necropsia os principais achados foram abdômen e tórax com presença de nódulos tumorais de consistência macia e aos cortes eram de coloração pardo-rosada. Histologicamente eram constituídos de células mesoteliais malignas, predominando células epitelioides arranjadas em cordões. Havia metástase nos pulmões, rins e em vasos linfáticos do coração. Amostras foram submetidas à análise imuno-histoquímica e as células tumorais apresentaram imunorreação citoplasmática para anti-célula mesotelial humana (HBME-1) e anti-citoqueratina (AE1/AE3), além de moderado índice proliferativo evidenciado pela reação contra o antígeno nuclear de proliferação celular (PCNA). Não houve marcação para vimentina e anti-antígeno epitelióide (EMA). Assim, a análise anatomopatológica e imuno-histoquímica evidenciou tratar-se de mesotelioma epitelioide trabecular de moderado índice proliferativo com múltiplos sítios metastáticos. [ABSTRACT FROM AUTHOR]

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