Parachordoma--a clinicopathologic, immunohistochemical, electron microscopic, flow cytometric, and cytogenetic study.

A case of parachordoma in a 45-year-old female was described. Histologically, the recurrent lesion, in comparison with the primary tumor, demonstrated an increased cellular atypia and mitotic rate. The tumor cells expressed EMA, vimentin, S 100 protein, and also a trace desmin content was present. Electron microscopic study provided no characteristic features of the tumor type studied. Flow cytometric evaluation of the DNA demonstrated a diploid histogram with the relatively high S-phase. Cytogenetic analysis revealed normal karyotype, but a deviation from the diploid state in the form of aneuploid metaphases with non-clonal structural chromosomal aberrations was observed.