Image Description
Endodermal sinus (perivascular) pattern in a post-pubertal yolk sac tumor of the testis. Numerous Schiller-Duval bodies are present. They have a single central thin-walled vessel in a hyalinized stroma surrounded by a layer of columnar or cuboidal cells. The tumor cells have large vesicular nuclei and prominent nucleoli. The papillary structures are contained within cystic spaces.