Immature teratoma of the maxillary sinus: a rare pediatric tumor.

IMPORTANCE Noncongenital immature teratomas in the head and neck are extremely rare, and to our knowledge have not previously been reported in the maxillary sinus of a pediatric patient. OBSERVATIONS Teratomas are neoplasms that contain tissue from more than 1 embryonic cell layer that is foreign to the location where they arise and are most commonly found in the sacrococcygeal and gonadal regions in children. We present an unusual case of an immature teratoma in the maxillary sinus of a 10-year-old boy and discuss the diagnostic workup, management, and clinical course. CONCLUSIONS AND RELEVANCE Immature teratomas represent a subset of benign teratomas with immature elements that may carry a worse prognosis.