Yolk Sac Tumor : Polyvesicular Vitelline
Yolk sac tumor (YST) of the testis shows a variety of architectural patterns that are admixed in varying proportions. Polyvesicular vitelline: This uncommon pattern shows vesicles lined by flattened bland tumor cells surrounded by loose myxoid or fibrous stroma. Some of the vesicles have constriction creating a dumbbell or figure of 8 appearance. The epithelium is AFP positive. The vesicles may contain hyaline globules.