Dedifferentiated Liposarcoma Presenting as Dysphagia and Weight Loss: Common Symptoms but an Uncommon Diagnosis.

A 76-year-old woman was referred for 6 months of progressively worsening dysphagia and unintentional weight loss. An esophagogastroduodenoscopy demonstrated an area of extrinsic compression in the lower esophagus measuring 7 cm in greatest dimension. Contrast-enhanced computed tomography revealed a solid homogeneous mass in the lower middle/posterior mediastinum, laterally displacing the esophagus. Endoscopic ultrasound-guided fine-needle biopsy showed a hypocellular infiltrate of pleomorphic cells in a loose collagenous matrix. By immunohistochemistry, neoplastic cells were negative for epithelial, vascular, neural, and melanocytic markers. Fluorescent in situ hybridization detected MDM2 amplification, compatible with a diagnosis of dedifferentiated liposarcoma.