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Parachordoma of the buttock: an immunohistochemical case study and review.

We report a case of parachordoma occurring in the buttock of a 43-year-old man, and review 20 cases of parachordoma reported in the English literature. The tumor in our case was grossly 3 cm in dimension, solid, lobulated and grayish-white in color. Microscopically, the tumor consisted of epithelioid and spindle cells, and fibromyxoid stroma. The epithelioid cells were immunohistochemically positive for vimentin, S-100 protein, neuron-specific enolase, keratin, carcinoembryonic antigen and epithelial membrane antigen, and negative for HMB45. These findings are similar to those for chordoma rather than extraskeletal myxoid chrondrosarcoma. Although the etiopathogenesis of parachordoma remains obscure, Schwann cells or some other neuron-related cell origin are suspected.