A case of neonatal mature teratoma transformed to malignancy in the neck extending to the mouth floor.

A case with neonatal teratoma originating from the cervicofacial region which transformed to be malignant during treatment is reported. The case is a full-term baby girl with swallowing difficulty and has a mass at the floor of her mouth with the right neck swelling. The mass was revealed to be multi-cystic and extending deep into the sublingual space and protruding outside. Puncture and marsupialisation of the cyst could not relieve her symptom and the tumor was resected in three occasions and was diagnosed as mature teratoma without malignant component. However, three months after the last resection, the solid right neck mass enlarged rapidly and the serum alpha-fetoprotein level was elevated. Biopsied specimen demonstrated the mass to be germ cell tumor with embryonal carcinoma and yolk sac tumor component. Eight courses of JEB regimen with recurrent mass resection successfully lead to complete regression without compromising patient growth as well as cosmetics. Head and neck teratomas in children are mostly benign amenable to curative excision but its rarity and site and size of the tumor make its treatment challenging. It is important to have multi-disciplinary management for the disease from neonatal period until growth has finished. There exists a relationship between the age at diagnosis and outcome of a patient with teratoma and head and neck teratomas in neonate are mostly benign but should be removed completely as soon as the patient condition is stabilized to reduce the risk of malignant change.