PERICYTOSIS AND EDEMA GENERATION - A UNIQUE CLINICOPATHOLOGICAL VARIANT OF MENINGIOMA

OBJECTIVE: We report a group of eight patients with a distinctive hist ological variant of meningioma that is associated with severe peritumo ral edema. The clinical presentation, radiographic findings, and histo logy of this type of tumor may lead to misdiagnosis as an aggressive o r malignant process. METHODS: We reviewed the histology from patients who had removal of meningiomas performed in our institution between 19 78 and 1992. Tumors having abnormal proliferation of cells in the intr amural vascular spaces were selected for study; case histories and rad iographs were reviewed. Tumor material was subjected to special stains , immunocytochemical examination, and electron microscopy. RESULTS: Se veral lesions were misread radiographically as being malignant. Patien ts underwent craniotomy with complete excision of the tumor. All lesio ns were small (less than or equal to 3 cm), and no brain invasion, unu sual tumor vascularity, or dural sinus involvement was noted in any ca se. Histologically, the meningioma pattern in each case was meningothe lial and benign in appearance. The immunocytochemical and electron mic roscopic features of the unusual cells in the blood vessel walls are m ost consistent with their being of pericytic origin. All patients have remained asymptomatic and without evidence of tumor recurrence with f ollow-up from 3 to 12 years. CONCLUSION: These tumors showed prolifera tion of pericytes in blood vessel walls and represent a new subtype of meningothelial meningioma. The apparently benign nature of these lesi ons necessitates their recognition. Characteristic findings of pericyt ic proliferation associated with edema generation have led us to descr iptively term this the PEG variant of meningioma.