Image Description
The microscopic features are similar in both pre- and postpubertal yolk sac tumors (YST). The tumor cells are arranged in a variety of architectural patterns that recapitulate the yolk sac, allantois, and extraembryonic mesenchyme. Multiple patterns coexist within the same tumor in varying proportions. Germ cell neoplasia-in-situ (GCNIS) is not present in the adjacent testis in pure YST in children. In contrast, GCNIS is a constant finding in testicular GCT in adolescents and young adults.
The architectural patterns include (in order of decreasing prevalence): microcystic/reticular, myxomatous, solid, glandular/alveolar, macrocystic, endodermal sinus/perivascular, hepatoid, papillary, sarcomatoid/spindle cell, parietal, and polyvesicular vitelline pattern.
Microcystic (reticular) pattern (most common): The tumor cells have large intracellular vacuoles, compressed nuclei and delicate strands of interconnected cytoplasm creating a spider-web like arrangement, frequently containing hyaline globules. In some areas, there are interconnecting ribbons and cords of tumor cells enclosing round/irregular extracellular spaces and creating a honeycomb-like meshwork. These spaces are often filled with basophilic myxoid material. Microcystic pattern often coexists and intermingles with myxomatous and solid patterns.
The architectural patterns include (in order of decreasing prevalence): microcystic/reticular, myxomatous, solid, glandular/alveolar, macrocystic, endodermal sinus/perivascular, hepatoid, papillary, sarcomatoid/spindle cell, parietal, and polyvesicular vitelline pattern.
Microcystic (reticular) pattern (most common): The tumor cells have large intracellular vacuoles, compressed nuclei and delicate strands of interconnected cytoplasm creating a spider-web like arrangement, frequently containing hyaline globules. In some areas, there are interconnecting ribbons and cords of tumor cells enclosing round/irregular extracellular spaces and creating a honeycomb-like meshwork. These spaces are often filled with basophilic myxoid material. Microcystic pattern often coexists and intermingles with myxomatous and solid patterns.