Lack of alkaline phosphatase activity predicts meningioma recurrence.

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.