Journal of Pediatric Surgery Case Reports (Mar 2025)
Posterior mediastinal Müllerian duct cyst in a child: A case report
Abstract
Introduction: Müllerian duct cysts were described in 2005 and are most common in peri- and postmenopausal women. Müllerian cysts have not been described in young children. Case presentation: A previously healthy 4-year-old girl with bronchitis was admitted to our hospital. A plain chest X-ray showed an abnormal mediastinal shadow. A contrast-enhanced computed tomography of the chest revealed a homogeneous tumor in the left posterior mediastinum, showing no contrast enhancement or calcifications. The tumor measured 9.1 × 4.7 × 3.8 cm and extended from the 5th to the 10th vertebral bodies. A chest magnetic resonance imaging confirmed the cystic posterior mediastinal mass with low signal intensity on T1-weighted and high signal intensity on T2-weighted images. With the presumed diagnosis of lymphangioma, the patient was taken to the operating room for a thoracoscopic mediastinal tumor resection. The patient was placed in right lateral decubitus and three ports were placed in the left pleural space. We found the cyst on the dorsal side of the lower lobe of the left lung. The cyst was not adherent to the diaphragm or the lower lobe itself, but was located near the intercostal arteries and veins, hemiazygos vein, and the sympathetic trunk. The cyst was carefully dissected off all surrounding structures. We opened the cyst, drained its serous fluid, and removed it entirely. The pathological analysis showed a monolayer of cuboidal cells with atypical round nuclei covering the cyst wall. The immunohistochemical analysis revealed positivity for PAX8 and estrogen receptor, and negativity for progesterone receptor and calretinin. These findings confirmed the diagnosis of a Müllerian duct cyst. The postoperative course was uneventful, and the patient was discharged home on the fifth postoperative day. At 6 months follow-up, no recurrence has been observed. Conclusion: Müllerian duct cysts are extremely rare in the pediatric population but should be considered in the differential diagnosis of mediastinal cysts in children.
