[Primary malignant lymphoma in the dura and subdural space along the superior sagittal sinus. Case report]

A 56-year-old male with a 11-month history of late-onset epilepsy was hospitalized because of status epilepticus. The physical examination and laboratory data were normal. Neurological examination revealed weakness of the right leg. Coronal computed tomography showed a mass of slightly high density in the bilateral parietal convexity, with homogeneous enhancement by contrast medium. Magnetic resonance imaging disclosed an en-plaque epidural tumor in the parietal region along the superior sagittal sinus, which was normointense on T1- and T2-weighted images. Conventional and digital subtraction angiography showed an avascular mass between the superior sagittal sinus and the inner table of the skull at the parietal region. The mass was thought to be situated in the parietal epidural space. On surgery, however, the tumor was found to be located mainly in the dura and subdural space. The histological diagnosis was malignant lymphoma of the B cell type. Ga-scintigraphy, physical examination, and bone marrow and peripheral blood examinations disclosed no systemic abnormalities. Therefore, the tumor was interpreted as a primary intracranial malignant lymphoma. Reports of primary intracranial malignant lymphoma have been increasing, but most have been located in the cerebrum. The dural-subdural location in this case is evidently rare.