Pathological and immunohistochemical studies of nephroblastoma in an adult chicken

Nephroblastoma or embryonal nephroma or Wilm's tumour is one of the most common types of renal neoplasm observed in young chickens. It originates from normal nephrogenic blastema and the proliferation of epithelial structures and supporting stroma of mesenchymal elements leading to tumour formation. This study describes the pathomorphology and immunohistochemical findings of nephroblastoma in an adult chicken. Grossly, the tumour appeared as solitary irregularly round growth in cranial lobe of the left kidney. Histopathologically, it revealed irregular masses of tubules comprised of large, irregular, cuboidal and undifferentiated cells with hyperchromatic nuclei surrounded by marked fibrous connective tissue proliferation. At places, the epithelial cells of few tubules showed keratinization as a result of metaplasia. Based on gross and microscopic findings, it was diagnosed as nephroblastoma. The immunohistochemical studies revealed moderate to intense cytoplasmic immunoreactivity for pan-cytokeratin (PCK) in the epithelial components of well-formed tubules. However, mild to moderate PCK immunoreactivity was observed in poorly differentiated deformed tubular structures, while no immunoreactivity was observed in the primitive glomeruli-like structures. Immunoreactivity to cytokeratin-14 and p53 immunomarkers was also not observed in any component of the tumour.