MICROCYSTIC MENINGIOMA - CLINICOPATHOLOGICAL FEATURES OF 6 CASES

The clinical and morphological features of 6 patients with unusual men ingiomas with extensive microcystic formation are presented. There wer e 4 males and 2 females, ranging in age from 30 to 64 years. The clini cal and neuro-imaging features of these tumours were identical with th ose of meningiomas in general. Morphological examinations disclosed th at the tumour cells in 4 cases had many ultrastructural characteristic s in common with the arachnoid cap cells, viz. prominent and complex i nterdigitation of the fine cytoplasmic processes, many desmosomes, and intracytoplasmic microfilaments. in contrast, the tumour cells of 2 c ases had characteristic structures in common with trabecular arachnoid cells, viz. stellate in shape, a small number of intracytoplasmic fil aments, relatively thick cytoplasmic processes, and occasional desmoso mes. The tumour cells in these 2 cases were considered to recapitulate the subarachnoid structure and showed microcystic appearance. Althoug h the histogenesis of microcysts in meningiomas is considered not to b e uniform, the biological behaviour of these 6 tumours corresponded to those of meningiomas in general.