Orthopaedic Pathology

Chordoma is an uncommon malignant tumor that originates from the remnants of the embryonic notochord. In most of the reported cases, chordomas occur at the skull base or in the sacrococcygeal spine, but rarely in the thoracic spine. We report the case of a young man with a large thoracic chordoma. Materials and Methods: A 26 year-old man was admitted to the hospital complaining of intermittent chest pain and progressive dyspnoea. Clinical examination revealed diminished breath sounds. CT scan of the chest showed a large, well-defined extrapulmonary tumor (8 cm in diameter) at the Th6 and Th7 level, and a defect of the anterior margin of the thoracic vertebra was observed. Results: The surgical specimen revealed a partially encapsulated, gray-tan tumor (8 · 6 · 5.5 cm). Cut section appeared nodular and was composed of grayish-yellow soft tissue with areas of hemorrhage and necrosis. Light microscopy showed lobules and nests of variably sized, polygonal cells embedded within an abundant mucoid matrix. Scattered throughout were large cells featuring bubbly, vacuolated cytoplasm characteristic of physaliphorous cells. Areas of necrosis and hemorrhage were identified within the tumor. The tumor cells stained strongly positive for epithelial markers (pancytokeratins and epithelial membrane antigen) and mesenchymal markers (vimentin and S-100 protein). Conclusion: Chordoma is a rare malignant bone tumor that originates from notochordal remnants. Intra-thoracic mediastinal chordomas are extremely rare, representing only 3% of all chordomas.