Immunohistochemical and histopathological characters of renal mesenchymal tumor in a Wistar rat

A 15 weeks old male Wistar rat was having abdominal distention. Postmortem examination revealed a highly expansile mass with large cystic cavities and nodular growths on the abdominal wall. The tumor mass caused enlargement of the abdomen and nearly replaced the right kidney. The lesion was diagnosed as renal mesenchymal tumor by histomorphological examination which was aided by immunostaining. The distinctive feature of the present case was that the tumor was positive S100 and cytokeratin immunostaining, which has not been reported earlier.