Abstract: Background and purpose: Microcystic meningioma is a rare subtype of meningiomas, which is rare in domestic and foreign reports, and is mostly reported in cases. This study aimed to explore the clinicopathological features and identification of microcystic meningioma. Methods: We retrospectively analyzed two cases of microcystic meningioma including their clinical manifestations, histological features and immunohistochemical phenotypes, and reviewed the relevant literature. Results: Two cases were middle-aged patients, one male and one female. The male patient was diagnosed as having traumatic brain hemorrhage whereas the female patient was treated for headache. The lesions were located in the left frontal and right frontal areas, the maximum diameters were 5.75 and 5.47 cm respectively. Imaging changes showed “brain tumor”. Microscopically, tumor cells were loosely arranged to form microcapsules of different sizes with the cavity containing powdered slurry, and the tumor cells had vacuolar cytoplasm and slender cytoplasmic processes without typical swirling structures and psammoma body. Immunohistochemistry showed vimentin, epithelial membrane antigen (EMA) and progesterone receptor (PR) were positive, S-100, glial fibrillary acidic protein (GFAP), CD34 and creatine kinase (CK) were all negative, and positive rate of Ki-67 was 3%-5%. Both patients underwent surgical treatment and were followed up for 5-6 months. Before submission of this article in January 2018, both patients were generally in good condition, and no tumor recurrence was observed. Conclusion: Microcystic meningioma is a special subtype of meningiomas, and histopathology and immunohistochemistry can confirm the diagnosis. The current treatment is mainly surgery, and the prognosis is good.

Key words: Brain tumor, Microcystic meningioma, Immunohistochemistry, Pathological diagnosis