Epithelioid cellular chordoma of the sacrum: a potential diagnostic problem.

We describe a sacral chordoma composed of solid nests of epithelioid cells. The tumor originated in the presacral area. Extensive clinical workup did not reveal any other lesion in the patient. In contrast to typical chordomas, this tumor contained only rare physaliferous cells, had no myxoid stroma, and was immunohistochemically unreactive with the antibody to S-100. The diagnosis of chordoma was supported by electron microscopy, which showed that the tumor cells contained numerous mitochondria surrounded by profiles of rough endoplasmic reticulum. The abundance of mitochondria, the narrow intercellular spaces, combined with a lack of glycogen, and a lack of extracellular myxoid material accounted for the epithelioid appearance of the tumor. We report this case to point out that the cellular chordomas can appear epithelioid in the sacrum and they may resemble metastatic squamous or transitional cell carcinomas.