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Meningiomas usually are benign intracranial tumors. However, some recur despite gross total resection, invade surrounding structures, or, rarely, metastasize. Reduced expression of the nonspecific tissue-type alkaline phosphatase (Pal) has been reported in high-grade meningiomas. To search for a predictor for recurrence, we studied Pal expression by histoenzymology in a series of 54 meningiomas with gross total removal. Pal expression was mostly altered in grades II and III meningiomas (P = .000014) and meningiomas with high MIB-1 values (P = .001). Pal expression correlated with cytogenetic data (P = .000033) and with recurrence (P = .0064); all tumors that recurred had abnormal Pal expression (13/13). In univariate analysis, Pal expression was the only variable correlated with recurrence-free survival (P = .035). Histochemical detection of Pal is a useful, easy, and low-cost technique to predict recurrence in meningiomas.

CD44, a family of cell surface glycoproteins involved in cell–cell and cell–extracellular matrix adhesion, is widely expressed in the white matter of the normal brain and in astrocytic gliomas under its standard form (CD44s also called CD44H). On the other hand, several variants have been found in brain metastases and rarely found in gliomas. We have investigated by immunohistochemistry CD44H and CD44v6 expression in 28 oligodendrogliomas. All tumors were CD44v6 negative whereas nearly all tumors were immunolabelled with anti-CD44H antibody. Immunostaining increased in parallel with grade and was particulary strong around vessels and in tumoral subpial nodules. Western blot analysis showed that oligodendrogliomas expressed the same 80-kDa CD44 isoform as normal brain. Since gliomas may arise from a dividing progenitor cell, we also studied CD44H expression during the oligodendrocyte lineage in vitroin parallel with specific markers of the O-2A cells. Precursor cells (PSA–NCAM positive), O-2A progenitor cells, as well as preoligodendrocytes (A2B5 positive cells) and immature oligodendrocytes (O4 positive cells), coexpressed CD44H. Our data showed that CD44H is expressed by cells of the oligodendrocyte lineage in vitroand by oligodendrogliomas in vivoespecially in sites of dissemination such as subpial spaces. This suggests that CD44H could play a role in migration of tumor cells in oligodendrocytic tumors.

Meningiomas usually are benign intracranial tumors. However, some recur despite gross total resection, invade surrounding structures, or, rarely, metastasize. Reduced expression of the nonspecific tissue-type alkaline phosphatase (Pal) has been reported in high-grade meningiomas. To search for a predictor for recurrence, we studied Pal expression by histoenzymology in a series of 54 meningiomas with gross total removal. Pal expression was mostly altered in grades II and III meningiomas (P = .000014) and meningiomas with high MIB-1 values (P = .001). Pal expression correlated with cytogenetic data (P = .000033) and with recurrence (P = .0064); all tumors that recurred had abnormal Pal expression (13/13). In univariate analysis, Pal expression was the only variable correlated with recurrence-free survival (P = .035). Histochemical detection of Pal is a useful, easy, and low-cost technique to predict recurrence in meningiomas.