Abstract
Heterogeneous masses developing in the pleural cavity are most often malignant and can pose diagnostic challenges. Fibrous tumors of the pleura, liposarcoma, thymoma or lipoma most frequently affect this anatomic area. Surgical exploration and resection are often mandatory to make the definitive diagnosis. We report the case of a 54-year-old women who presented with an epigastric and right sub costal pain. A complete preoperative workup revealed a large tissular and fatty mass in the right costo-diaphragmatic angle suggestive of liposarcoma. Surgical resection resulted in the surprising diagnosis of hamartochondroma.