Congenital Retroperitoneal Teratoma in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is caused by mutations in the tumor suppressor gene NF1. The increased tumor risk in affected individuals is well established, caused by somatic biallelic inactivation of NF1 due to loss of heterozygosity. Pediatric teratoma has not been reported in individuals with NF1 previously. We report a case of congenital teratoma in an infant with a heterozygous maternally inherited pathogenic NF1 mutation (c.[1756_1759delACTA] and p.[Thr586Valfs*18]). We detected a "second hit" in the form of mosaic whole NF1 deletion in the tumor tissue using multiplex ligation-dependent probe amplification, as a proof to support the hypothesis of NF1 involvement in the pathogenesis of teratoma.