Pediatric Head and Neck Germ Cell Tumors: Current Management and Risk of Malignant Transformation.

Background And Aims: Head and neck germ cell tumors (HN-GCTs), excluding the central nervous system, are rare and frequently contain mature or immature teratoma (MIT) compounds. The aims of this study were to analyze the risk of malignant transformation after MIT HN-GCTs, to describe treatments and sequelae, and to propose recommendations for the follow up of these patients.

Methods: National multicentric retrospective study of all patients aged from birth to 17 years, treated in France between 2000 and 2021 for a HN-GCT of all histotypes. Patients were selected from various sources: French National Registry of Childhood Cancers, SFCE (Société Française des Cancers de l'Enfant) centers and pediatric ENT (ear, nose and throat) surgical centers.

Results: A total of 152 patients were selected. Median age at diagnosis was 9 months (range, 0-190), with 34 diagnosed antenatally. Overall, 150 tumors contained MIT and two were malignant yolk sac GCT (YST). All patients, except for two cases with early postpartum death, underwent surgery, preceded in 12 cases by an EXIT (Ex Utero Intra Partum) procedure. After a median follow-up of 47 months (range, 11-124), four patients with MIT developed a localized mature teratoma relapse, three developed a localized secreting malignant HN-GCT (including two malignant degenerations after MIT), and one had a thoracic neuroblastoma. All patients survived. 9% of survivors developed moderate to severe sequelae.

Conclusions: Due to the low rate of malignant degeneration (two out of 148, 1.3%), this study does not support systematic oncologic long-term monitoring after neonatal MIT HN-GCT. However, regular clinical examination is required to detect and treat locoregional sequelae.