Case Report of a Giant Mediastinal Neurofibroma Misdiagnosed as Massive Pleural Effusion.

Mediastinal neurogenic tumors are benign neoplasms commonly found along nerves in the posterior mediastinum, with rare malignant transformation. We report a case of a 36-year-old woman admitted to the respiratory department with complaints of chest tightness, cough, and sputum production. Chest CT revealed a large hypodense lesion in the left thoracic cavity with scattered streaky hyperdense shadows, initially suspected as massive pleural effusion. Thoracentesis failed to aspirate fluid. Subsequent ultrasound and contrast-enhanced CT identified a giant mediastinal mass, prompting referral to thoracic surgery for resection. The tumor was successfully removed, and postoperative pathology confirmed neurofibroma. The patient recovered well and was discharged. For unexplained hypodense lesions in the thoracic cavity, ultrasound and contrast-enhanced CT aid in reducing misdiagnosis. For large intrathoracic tumors, successful resection requires thorough preoperative evaluation, preparation, and optimal surgical access to ensure safe and complete removal.