Atypical fibrous histiocytoma with myxoid stroma: a rare lesion arising from dura mater of the brain.

Intracranial fibrohistiocytic tumors are rare. This report is concerned with a 24-year-old white male who had an 8 month history of intermittent visual disturbance. Craniotomy revealed a large, completely intradural lesion on the floor of the left anterior cranial fossa without involvement of the leptomeninges or brain parenchyma. Gross and microscopic examination revealed that the fibrogenic portion of the tumor was composed of spindle shaped neoplastic cells arranged in storiform pattern, a hallmark of fibrohistiocytic tumor. In contrast to three previously reported cases of "fibrous xanthomas" involving the leptomeninges and superficial cortex of the brain, the present lesion is clearly originated from mesenchymal stem cell of the dura. The other distinct gross and microscopic feature was the presence of myxoid component which constituted about 40% of the entire lesion. The myxoid component had not been observed in previous 5 reported cases of intracranial fibrohistiocytic lesions. Since there was cellular pleomorphism with extremely rare mitosis, it was felt that the lesion be best designated as atypical fibrous histiocytoma with myxoid stroma.