Immature teratoma with microscopic yolk sac tumor: A case of diagnostic challenge on histology

Abstract

An adolescent girl with raised alpha-fetoprotein (AFP) levels presented with a left-sided large solid ovarian mass. Microscopically, the tumor was composed of a variety of immature and mature tissues derived from the three germ layers having very sparse (single focus of) immature neuroepithelium. Few areas also showed the presence of a reticular pattern of yolk sac tumor (YST). Hence, the tumor was diagnosed as immature teratoma with microscopic foci of yolk sac elements. After 6 months of cisplatin-based chemotherapy, she developed a recurrence which was composed of mature teratoma on histology. In this case, the single focus of immature neuroepithelium caused a difficulty in labeling this tumor as an immature teratoma which otherwise resembled a mature teratoma. The raised AFP levels suggested the presence of yolk sac element, the classical form of which was seen at microscopy in only a few areas. As compared to the markedly elevated serum AFP levels, the classical yolk sac tumorous area was very limited thus advocating the view that differentiated glands with subnuclear vacuoles similar to immature endoderm represent well-differentiated forms of YST.[1]