Extragonadal Germ Cell Tumors: The Intriguing Pediatric Stories Continue…

Extragonadal germ cell tumors (EGCTs) may develop at unusual locations, with atypical presentations and inconclusive radiological findings, thus being quite baffling for the pediatricians. Overall, germ cell tumors being rare in children, constituting only 1%–3% of childhood tumors,[1] remain largely unsuspected. Unlike in adults, nearly half of the GCTs in children are extragonadal, the latter term being used only in the absence of any primary gonadal GCT. It is postulated that EGCTs develop due to an arrest or aberration in the migration of primordial germ cells while moving from the yolk sac endoderm along the dorsal mesentery to the genital ridge, localizing anywhere along the midline of the body, from the brain to the coccyx. Although the most common anatomical sites for EGCTs include the mediastinum, retroperitoneum, sacrococcygeal area, and brain, they are notorious for their appearance in unusual sites, such as the pineal gland, bladder, vulva, pelvis, uterus, kidney, nasal sinuses, and so on. This issue of the Indian Pediatrics Case Reports publishes a case report[2] of EGCT, in yet another atypical location – the vagina, causing persistent vaginal bleeding in a 7-month-old infant – a picture indeed puzzling for the pediatrician. These tumors are histologically heterogeneous, being broadly of two types: seminomatous and nonseminomatous tumors, the latter group is again heterogeneous including teratoma, embryonal carcinoma, yolk sac carcinoma, and choriocarcinoma. To add to the diagnostic confusion, a single tumor may contain different histological types, referred to as mixed GCTs, a finding seen in a quarter of the pediatric GCT/EGCTs. While the yolk sac tumor is the most common malignant GCT, teratomas (both mature and immature) are considered benign. However, microscopic elements of yolk sac tumor maybe found in immature teratomas, making the latter potentially malignant.[1] Radiological imaging such as ultrasonography and contrast-enhanced computed tomography supplemented with tumor markers such as alpha-fetoprotein (αFP) and beta-human chorionic gonadotropin may provide clues but cannot reveal the diagnosis, αFP levels being physiologically high in young infants. The second case report of EGCT published in this issue[3] highlights this diagnostic challenge in a 3-month-old infant, where even a needle aspiration cytology was inconclusive. The Indian guidelines[4] state that clinical and radiological evidence of a heterogenous tumor in a location consistent with that of GCT with an elevated αFP is enough to diagnose the presence of endodermal sinus elements in the tumor. Treatment is advocated based on staging as per the Children’s Oncology Group and risk stratification. The two cases published here underwent different management strategies – the retroperitoneal immature teratoma was surgically resected with no chemotherapy, whereas the infant with vaginal GCT, possibly an embryonal carcinoma was subjected to chemotherapy; both cases showed favorable outcomes at the last follow-up. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.