PATHOLOGICAL SIGNIFICANCE OF MENINGEAL ENHANCEMENT (FLARE SIGN) OF MENINGIOMAS ON MRI

BACKGROUND The purpose of this study was to clarify the pathologic fea tures and clinical significance of the meningeal enhancement surroundi ng meningiomas (''flare sign'') on contrast-enhanced T-1-weighted magn etic resonance images (MRI). METHODS The marginal dura mater of tumors was resected from nine cases of meningioma exhibiting a flare sign an d used for histopathologic evaluation, RESULTS Connective tissue proli feration was found in the dura mater in all cases, vascular proliferat ion was found in three, and tumor cell nests were observed in four cas es. In one case, tumor cells were found 4.5 mm from the edge of the tu mor. In another case, a meningothelial cell cluster was found, CONCLUS IONS These results suggest that tumor cell nests are present frequentl y in dura mater that exhibits the flare sign, and that the dura mater near these lesions should be resected as widely as possible. (C) 1997 by Elsevier Science Inc.