Primary intracranial mucosa-associated lymphoid tissue lymphoma. A report of two cases and literature review.

Low-grade B cell non-Hodgkin lymphomas typically arise from the marginal zone of the secondary lymphatic follicles. Their intracranial expression is very rare, most frequently affecting the dura mater and the choroid plexus glomi in the lateral ventricles. Their initial evaluation requires the exclusion of more common extra-axial lesions, such as meningiomas, dural metastasis, granulomatous lesions or secondary lymphoproliferative dural extension from body lymphomas. Whenever a ventricular lesion is present, the patient's age and lesion location help narrow the differential diagnosis. Dural-based lymphomas and ventricular/choroid plexus lymphomas are slow-growing lesions with imaging features similar to meningiomas, which is typically their main differential consideration. Diffusion-weighted images frequently show restricted diffusion behaviour on lymphomas, helping to differentiate them from the typical meningiomas.