[Intratumoral hemorrhage associated with cystic meningioma under observation: a case report].

Cystic meningiomas are not commonly encountered and are said to account for only 1 to 2% of all types of meningioma. There have been several reports on them and most of them were discussed under the aspect of the mechanism of cystic formation. Though few reports present the process of cystic formation, here we were able to present the process of cystic formation with intratumoral hemorrhage. The case was a 56-year-old man who presented with urinary incontinence. MRI revealed a large cystic tumor in the right frontal lobe and he was admitted to another hospital. After 20 days, MRI incidentally revealed hematoma near the intratumoral cyst. Two weeks later, MRI revealed that the hematoma flowed out the cyst and the cavity of the hematoma communicated with the cyst. Angiography showed that the tumor was fed by the left anterior ethmoid artery. After surgical removal of the tumor, histopathological diagnosis was that the tumor was a transitional meningioma and there were no findings of malignancy. Commonly, intratumoral hemorrhage is unusual for a meningioma but we suspect that there are not a few cases in which small hemorrhage occurred without symptoms and the hematoma cavity joined the intratumoral cyst while the cyst grew gradually.