Yolk Sac Tumor : Parietal Pattern
Yolk sac tumor (YST) of the testis shows a variety of architectural patterns that are admixed in varying proportions. Parietal pattern: There is large amount of dense, eosinophilic basement membrane material surrounding individual tumor cells or groups of cells. In extreme cases, the tumor is hypocellular and consists of only scattered neoplastic cells in an abundant eosinophilic matrix. This pattern is rare and is seen more commonly after chemotherapy in metastases or late recurrences.
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