Immature teratoma of the ovary with microscopic yolk sac tumor in children and adolescents: A multi-institutional study

Objective: Immature teratoma (IT) of the ovary is an uncommon tumor with controversial management. The significance of microscopic yolk sac tumor (YST) within ovarian IT is unclear. We therefore aim to review the characteristics, management and outcomes of pediatric and adolescent patients with ovarian IT containing microscopic foci of YST and compare these patients to those without microscopic foci of YST, with a specific focus on recurrence-free survival (RFS). Methods: A multicenter review was performed by 29 institutions participating in the Pediatric Surgical Oncology Research Collaborative of females <18 years with ovarian IT diagnosed between 2010 and 2022. Patients with microscopic foci of YST (defined as ≤5% or documented by the institutional pathologist as a microscopic, single focus) were compared to those without. Results: We identified 143 females with ovarian IT, with 16 (11.1%) containing microscopic foci of YST. Patients with microfoci of YST were more likely to have higher-grade, higher-stage tumors, and higher alpha fetoprotein values at diagnosis than those without microscopic YST. Those with microscopic YST were more likely to receive chemotherapy (68.8%). There were 3 overall recurrences in the YST group (18.8%). There was no difference in RFS between those with and without YST; malignant recurrence was seen in 6.25% of those with YST vs. 7.1% of those of without. Conclusions: Children and adolescents with ovarian IT containing microscopic YST have favora