Abstract
Giant mediastinal teratomas in the pediatric population are uncommon entities that may grow insidiously and cause significant compression of intrathoracic structures. We report the case of a 10-year-old girl with a two-year history of progressive exertional dyspnea, chest pain, orthopnea, and increasing thoracic enlargement. Chest radiography demonstrated marked mediastinal widening, and contrast-enhanced chest CT revealed a predominantly cystic mediastinal mass measuring approximately 15 × 14 cm, with mediastinal shift and ipsilateral lung collapse. Routine laboratory tests were within normal limits, and surgical resection confirmed a mature mediastinal teratoma. The patient had an uneventful postoperative course, and follow-up CT showed complete pulmonary re-expansion with no residual lesion. This case highlights the clinical and imaging features that should raise suspicion for a giant mediastinal teratoma in children and underscores the importance of reporting these cases given the limited pediatric literature available.