Dog with metastatic papillary mesothelioma causing abdominal swelling

Abstract

A six-year-old female Dachshund presented intense abdominal distension caused by hemorrhagic effusion. Cytological examination of the fluid was performed and suggested a carcinoma. The animal was submitted to exploratory laparotomy and histological examination of the substantially altered spleen revealed epithelioid mesothelioma. Owing to a poor prognosis, poor response to chemotherapy, and development of thoracic effusions that required daily drainages, the owners decided for euthanasia. At necropsy, besides a 600 mL of sera‐hemorrhagic abdominal fluid, no abnormal gross finding was identified in the abdominal cavity. The thoracic cavity was also filled with approximately 200 mL of effusion with same features as those detected in the abdominal fluid. A few firm white-to-gray nodules, with sizes ranging from 0.1 to 0.3 cm, were found in the lungs and diaphragm. Samples of the nodules were stained for routine histopathology and submitted to immunohistochemistry (IHC) assays using the antibodies vimentin, PAN Cytokeratin, calretinin, and TTF-1. Histopathology and IHC findings confirmed the diagnosis of metastatic papillary mesothelioma.