Journal of Immunology and Immunopathology

Pleural mesotheliomas in dogs are typically infrequent and rare. This report focuses on a nine-year-old male Labrador Retriever dog presenting with a history of dyspnea and reluctance to move. Clinical and ultrasound examinations revealed pleural effusion. The effusion was aspirated via ultrasound-guided thoracocentesis and subjected to further laboratory investigations. Cytological examination of the fluid and cell block technique confirmed the presence of numerous variably sized clusters of neoplastic mesothelial cells. Immunohistochemistry using Mesothelin demonstrated positive expression with a brown color reaction in both the membrane and cytoplasm. Based on the cytology, cell block technique, and positive reactivity to Mesothelin by immunohistochemistry, the case was diagnosed as pleural mesothelioma.