Human meningiomas: immunohistochemical localization of progesterone receptor and heat shock protein 27 and absence of estrogen receptor and PS2.

Formalin-fixed, paraffin-embedded tumor specimens from 64 human meningiomas of various histologic types were immunostained using a streptavidin-peroxidase method and monoclonal antibodies for estrogen receptors (ER) and progesterone receptors (PgR) and hormone-induced proteins PS2 and heat shock protein 27 (Hsp27). The immunohistochemical analysis was scored in a semiquantitative fashion incorporating both the intensity and distribution of specific staining (score). Strong PgR nuclear immunoreactivity (mean score, 54.2) was observed in 51 of 64 meningiomas (80%). Meningiomas with atypical features were negative for PgR. Low Hsp27 cytoplasmic immunoreactivity (mean score, 9.8)--irrespective of histologic type--was observed in 26 of 64 meningiomas (40%). Whor1 formations in transitional meningiomas were Hsp27-positive. Hsp27 immunoreactivity was observed in tumor blood vessels. All neoplasms were negative for ER and PS2. Normal arachnoid tissue was positive for PgR and negative for ER, PS2, and Hsp27. Compared with previously reported data on gliomas, the results of this study indicate that meningiomas show a clear out difference concerning the expression of PgR and Hsp27.