Parachordoma or chordoma periphericum? Case report of a tumor of the thoracic wall

Abstract We report the findings from an aspiration biopsy and resection of a chordoma‐like tumorous mass in the wall of the thorax of a 36‐yr‐old man with immunohistochemical, ultrastructural, and cytogenetic studies. The 4‐cm oval tumor was an incidental finding on physical examination, and no other lesions were identified after comprehensive radiologic studies. The aspirate was composed of sheets and nests of cells with distinct borders in a myxoid and fibrillary extracellular matrix. The neoplastic cells were uniform and round or polygonal with abundant pale blue vacuolated cytoplasm and small round, central or eccentric nuclei. On electron microscopy, mitochondrial rough endoplasmic reticulum complexes were seen in neoplastic cells. These features were similar to those of a conventional chordoma. However, the cytogenetic pattern, 43,XY,‐1,‐2,der (5)t(1p;5q),‐6,add(8p),add(10q), was not typical. In addition, the neoplastic cells were positive for vimentin, S‐100, AE1/AE3, CAM 5.2, and CK 19; were focally positive for EMA and smooth muscle actin; and were negative for cytokeratin 1 and 10 (34βE12), CK 7, CK 8 (35H 11B), CK 17, and CK 20. The cytogenetic and immunohistochemical patterns were different from conventional chordoma and its peripheral counterpart, chordoma periphericum, suggesting the diagnosis of parachordoma. To the best of our knowledge, this is the first report of fine‐needle aspiration of this newly defined and rare entity. Diagn. Cytopathol. 2003;29:18–23. © 2003 Wiley‐Liss, Inc.