Cystic meningiomas: Radiological and pathological correlation with surgical implications.

INTRODUCTION: Meningiomas associating prominent cystic changes (CM) have challenged neurosurgeons since the beginning of this surgical discipline. We present the experience in the diagnostic and therapeutic management of this entity in our institution.

MATERIAL AND METHODS: A review of our patient database was carried out, searching for those CM that were operated on in the last 15 years. Relevant clinical data were recorded and analyzed for each case, with special emphasis in the correlation of radiological and pathological findings. Cystic changes were classified according to the scheme proposed by Nauta et al. RESULTS: A total of 11 patients were gathered, which represents 1.8% of the meningiomas operated on in our department during the period studied. All were adults, predominantly female patients (8 cases). Among the clinical symptoms a high rate of epileptic seizures was observed while only one patient developed acute intracranial hypertension. Morphologically, most tumors corresponded to type 2 CMs, followed by types 1, 3 and 4. In only five patients an unequivocal radiological diagnosis of meningioma could be made. All neoplasms were surgically removed and there were no records of recurrence (mean follow-up: 52.8 months). Microscopic findings were consistent with the pathological diagnosis of atypical meningioma in 4 cases, while the remaining tumors corresponded to OMS grade I neoplasms with variable microscopic patterns.

CONCLUSIONS: Meningiomas can exceptionally associate cystic changes, both intra and/or extratumoral, in variable number and size. When cystic changes become too prominent (a large number or big-sized cysts), a serious preoperative diagnostic dilemma may arise. The surgical management of those CMs displaying a peripheral, thin-walled cyst (types 2 and 3) is especially complex, as contrast enhancement of the tumor wall did not correlate strictly with neoplastic invasion; even in the absence of this feature free floating islands of meningothelial cells intermixed with cyst fluid can be found. Consequently both surgical biopsy of every suspicious tissue and copious irrigation of the surgical cavity are strongly recommended for these CM types.