Typical and atypical MR imaging features of intracranial epidermoid tumors.

OBJECTIVE: We categorized the MR imaging characteristics of intracranial epidermoid tumors. MATERIALS AND METHODS: MR images from 23 cases of intracranial epidermoid tumors were reviewed retrospectively. Signal intensities of tumor relative to surrounding structures were noted, as were the internal architecture of the tumors and the presence and degree of hydrocephalus. RESULTS: Seventeen (74%) of 23 cases of intracranial epidermoid tumors were revealed as slightly hyperintense relative to CSF on T1-weighted MR images. Nineteen (95%) of 20 cases were hyperintense relative to CSF on proton density-weighted MR images. Fifteen (65%) of 23 cases were isointense to CSF on T2-weighted MR images, whereas the remaining eight cases (35%) were hyperintense to CSF on T2-weighted MR images. One (4%) of 23 cases showed signal intensity that was isointense to CSF on all pulse sequences. Fifteen (65%) of 23 cases showed heterogeneous signal characteristics on either T1-weighted or proton density-weighted MR images, or both. Eight (35%) of 23 cases showed a rim of hyperintensity on proton density-weighted MR images. Five (33%) of the 15 cases that received gadolinium showed rim enhancement. Five (22%) of 23 cases were multilocular, with different regions of tumors showing highly variable imaging characteristics. Two (9%) of 23 cases showed high signal intensity on T2-weighted MR images in the adjacent brain parenchyma. Two (9%) of 23 cases showed mild hydrocephalus. Six (43%) of 14 tumors that either originated in or secondarily involved the cerebellopontine angle also extended into the ipsilateral Meckel's cave. CONCLUSION: On T1-, proton density-, and T2-weighted MR images intracranial epidermoid tumors usually showed heterogeneous signal intensity that was hyperintense to CSF. On all spin-echo pulse sequences epidermoid tumors with signal characteristics isointense to CSF were unusual. Hydrocephalus, even in the setting of marked displacement and compression of the brainstem, was not usually seen on MR imaging. Meckel's cave was often involved secondarily with epidermoid tumors that involved the cerebellopontine angle.

Primary central nervous system lymphoma with systemic metastasis: case report and review.

Primary central nervous system lymphoma (PCNSL) almost always remains confined to the nervous system. We report a patient with well documented PCNSL who responded to treatment, but subsequently developed pathologically confirmed systemic metastases without repeated local failure 35 months after initial diagnosis. In a review of the world's literature we identified 5 other cases of PCNSL with histologically confirmed antemortem systemic metastases and a total of 62 cases of central nervous system (CNS) lymphoma in some way associated with extraneural lymphoma. These cases are classified and discussed. Clinicians caring for PCNSL patients must remain alert to the possibility of systemic metastasis, especially as local control of PCNSL improves.