P53 expression in choroid plexus neoplasms: an immunohistochemical study.

OBJECTIVE: To evaluate choroid plexus neoplasms for p53 expression. CASE MATERIAL: We studied 10 choroid plexus tumors (four papillomas and six carcinomas) by immunohistochemistry using the DO7 anti-p53 monoclonal antibody. RESULTS: Three of four choroid plexus papillomas demonstrated no staining. Scattered nuclear and rare cytoplasmic positivity was present in one papilloma, which showed foci of increased mitotic activity (labeling index 2.5%). Six of six carcinomas were immunoreactive for p53, and three cases had labeling indexes of over 70%. All immunopositive choroid plexus tumors (7/7) exhibited nuclear staining. Punctate cytoplasmic positivity was identified in 5 of 7 cases. CONCLUSION: Our study suggests that altered p53 expression is detectable by immunohistochemistry in choroid plexus neoplasms and is consistently present in choroid plexus carcinomas.