Divergent differentiation in choroid plexus papilloma. An immunohistochemical study of five cases.

Intermediate filament and S100 expression was studied in five cases of choroid plexus papilloma. All the cases showed positivity for S100 and Nimentin. Cytokeratin and glial fibrillary protein (GFAP) intermediate filaments were present in 80 pc of the cases. None of the cases expressed epithelial membrane antigen. These results confirm the divergent differentiation of choroid plexus tumours.