Meningioma: a clinicopathological evaluation

Abstract

As yet no unifying grading system for meningiomas has been adopted. We evaluate epidemiologic factors of meningioma in Iran & degree of agreement between the two commonly used grading systems namely WHO (2000) and Mahmood systems. During a 6-year period 238 meningiomas were selected and reviewed by two independent pathologists using both grading systems. 205(86.1%) cases were benign, 19(8%) atypical and 14(5.9%) malignant. 181(18%) cases were primary and 51(27%) secondary; 35(68%) of the latter benign, 7(14%) atypical and 9(18%) malignant. All intraspinal meningiomas were benign. In benign cranial and spinal types female to male ratios were 1.9: 1 and 1.3: 1 ; while in atypical and malignant types were 1 :1.4 and 1:3.1 respectively. Mean ages were 49.9 for benign. 41.1 for atypical and 50 for malignant types. The most frequent site of involvement in all grades of intracranial tumors was cerebral convexity (31.1 %). The most common subtype was menigothelial (65.1%). Female preponderance seen in benign nonrecurrent meningioma became increasingly less prominent and even reversed in recurrent, atypical and malignant forms. Benign recurrent tumors were similar to non-recurrent tumors microscopically. Kappa value comparing two grading systems was 0.947, so good agreements were found between Mahmood and WHO grading systems.

Keywords: Mahmood grading system; WHO grading system; brain tumor; intracranial; intraspinal; meningioma.

Figure 1 :

Some histologic features of different grades of meningioma: 1a numerous mitotic figures seen in malignant meningioma. 1b invasion of atypical meningioma (darker area) into the brain parenchyma (lighter area). 1c characteristic whorls of benign meningothelial meningioma.