Giant mediastinal lipoma with bilateral hemithoracic extension in a young woman: a case report

BACKGROUND: Mediastinal lipomas are rare benign tumors that usually remain asymptomatic until they reach a considerable size. Giant mediastinal lipomas can cause progressive respiratory symptoms and present diagnostic challenges by mimicking malignant lipomatous tumors. CASE PRESENTATION: We report a 33-year-old Iranian woman presenting with progressive dyspnea for one year. Chest radiography and contrast-enhanced CT revealed a giant, well-encapsulated fat-density mass in the anterior mediastinum, measuring approximately 214 × 123 × 159 mm, extending to the diaphragmatic level and into the contralateral hemithorax, without invasive features. The patient underwent complete surgical excision via median sternotomy. Intraoperatively, a large encapsulated fatty mass with minimal adhesions and no signs of invasion was identified. Histopathological examination confirmed a benign lipoma composed of mature adipocytes. The postoperative course was uneventful, with complete resolution of symptoms. CONCLUSIONS: Giant mediastinal lipomas are rare but should be considered in the differential diagnosis of fat-containing mediastinal masses. Cross-sectional imaging plays a pivotal role in diagnosis, while complete surgical resection provides definitive treatment with excellent outcomes.