[Imaging diagnosis of central nervous system malignant lymphoma]

With a typical case, imaging diagnosis of central nervous system malignant lymphoma is not difficult. High density on non contrast CT, periventricular location, homogenous contrast enhancement, iso- to hypointensity to gray matter on T(2) weighted MR imaging and high intensity on diffusion weighted MR imaging are characteristic findings. Hemorrhage is rare. When a patient is immunocompromised, irregular ring enhancement is noted on enhanced study. Intravascular lymphomatois is a rare type of lymphoma. A variety of imaging findings are reported. Differential diagnosis are many. Most difficult to distinguish is a tumefactive multiple sclerosis. Most of the reported cases of tumefactive multiple sclerosis are diagnosed by brain biopsy when the brain tumor, especially malignant lymphoma is suspected. CLIPPERS (chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids) has been recently identified. However, there still remains whether CLIPPERS is an actual new disease entity or represents overlapping disease.