Mature Teratoma of Posterior Mediastinum in a Newborn: A Case Report.

Teratomas are germ cell tumors that can appear in different parts of the body, most often in the ovaries or testes. Treatment depends on whether the tumor is mature or immature: mature teratomas are usually removed surgically, while immature ones often require chemotherapy as well. Teratomas located in the mediastinum, particularly in the back part (posterior mediastinum), are rare. These tumors are typically discovered by chance during imaging exams, and only a few cases cause noticeable symptoms. In this report, we describe a rare case involving a 9-day-old female newborn with no prior medical issues, who was brought to the pediatric emergency department with acute breathing difficulties. Her condition required admission to the neonatal intensive care unit due to respiratory failure. On examination, she had signs of respiratory distress, including a Silverman score of 6/10, fast breathing, and low oxygen levels. A chest X-ray revealed a mass in the left side of her chest, causing a shift in the mediastinum. A CT scan of the chest confirmed the presence of a large mass with both solid and cystic components in the posterior mediastinum, suggesting a mature teratoma. The baby underwent successful surgery to remove the tumor. Pathology confirmed it was a mature teratoma, showing a mass made up of different tissue types but no glial tissue. Her recovery went smoothly, with no complications during follow-up. This case underscores how unusual it is for newborns to have symptomatic mature teratomas in the mediastinum. It also highlights the importance of considering this diagnosis in infants with breathing problems and shows that early surgical treatment can lead to a good outcome.