Image Description
Polyembryoma is a distinct histologic form of mixed germ cell tumor. It consists of embryonal carcinoma and yolk sac tumor components arranged in organoid structures called embryoid bodies that resemble early embryo (13 to 18 days of gestation). Numerous embryoid bodies are seen in this image.
Usually, it is present along with other germ cell components but may be the dominant pattern in rare cases. The embryoid bodies consist of a central semicircular plate of cuboidal or columnar embryonal carcinoma cells, a dorsal space lined by flattened epithelium (reminiscent of amniotic sac), and a ventral yolk sac tumor component with reticular and myxomatous architecture. The embryoid bodies are surrounded by loose vascular tissue resembling extraembryonic mesenchyme.
Usually, it is present along with other germ cell components but may be the dominant pattern in rare cases. The embryoid bodies consist of a central semicircular plate of cuboidal or columnar embryonal carcinoma cells, a dorsal space lined by flattened epithelium (reminiscent of amniotic sac), and a ventral yolk sac tumor component with reticular and myxomatous architecture. The embryoid bodies are surrounded by loose vascular tissue resembling extraembryonic mesenchyme.