Adult extrarenal Wilms tumor of the uterus with teratoid features.

The present article reports for the first time a case of an extrarenal teratoid Wilms tumor in the uterus of a 62-year-old woman. It had triphasic histology with epithelial areas composed of metanephric tubules harboring glomerular structures, adamantine patterns, neural type rosettes, blastema, and a primitive, myxoid type stroma. Abundant heterologous elements such as cartilage, striated muscle, squamous epithelium, and an alpha fetoprotein and TTF1-positive early endodermal epithelium were also present. Immunohistochemistry in Wilms tumor areas showed positivity for markers also indicative of peripheral primitive neuroectodermal tumors such as neuron-specific enolase, CD99, and CD56. However, nuclear positivity for Wilms tumor antigen together with the presence of glomeruli and the absence of endometrioid tumor areas and the organoid arrangement of tissues excluded peripheral primitive neuroectodermal tumors, carcinosarcoma, and teratoma, respectively. Although the diagnosis of female genital tract Wilms tumors is difficult in cases where glomerular structures are lacking, it should be considered because these neoplasms have a better therapeutic response than peripheral primitive neuroectodermal tumors and carcinosarcoma.