A case of paravertebral mediastinal chordoma without bone destruction.

We report a unique case of mediastinal paravertebral chordoma without bone destruction in a 47-year-old Japanese woman. She was admitted to hospital after a tumor was incidentally detected on a chest radiograph. The tumor was located in the paravertebral region of the mediastinum and did not show any destruction of the thoracic vertebra radiologically. The tumor was clinically diagnosed as a benign neurogenic tumor and the tumor was easily removed surgically. Microscopically, the tumor mainly consisted of tumor cells with extensively vacuolated cytoplasm, arranged in cord- and nest-like fashion against a myxoid matrix background. Immunohistochemically, the tumor cells showed diffuse positivity for pancytokeratin (AE1/AE3) and vimentin. The tumor cell nuclei were positive for brachyury, which is a key transcription factor of notochordal development. These results confirmed the tumor to be an extraosseous chordoma in the paravertebral mediastinal region, which is an extremely rare location for a chordoma.