Recurrent meningiomas--the immunohistochemical analysis of angiogenesis and cellular proliferation. Preliminary study.

Meningiomas exhibit a tendency to the local regrowth after their surgical resection, and some of those recurrent tumors show histological malignancy progression. The present study was performed on 10 cases of recurrent meningiomas chosen out of total 122 meningiomas diagnosed in our Department of Pathomorphology in the period 1993-1998. The tissue material from both operations was examined. One patient was operated three times. In three cases at the second operation there was progression from benign to atypical meningioma. The other tumors did not change their histological grade (four benign, one atypical and two anaplastic). The tumor tissue section were stained immunohistochemically with monoclonal antibodies raised against epithelial membrane antigen (EMA), Ki-67 and von Willebrand factor (vWf). The percentage of EMA-positive cells and Ki-67 immunoreactive cells (proliferation cell index--PCI) were counted. The vascular density (number of blood vessels/mm2) was assessed in the preparations stained with anti-vWf, as the measure of the intensity of angiogenesis. The values of the examined parameters were greatly differentiated within both the initial and the recurrent tumor groups. The values of vascular density ranged 12-96 vessels/mm2, the percentage of EMA-positive cells was 0.75%, PCI was from 0.3 to 9.3%. The values of the examined parameters did not differ significantly between initial and recurrent meningiomas groups. It is however worth to point out that PCI in the most recurrent tumors were higher than in their primary counterparts.