Waldenström's disease is a B-cell, low grade lymphoma, secreting an immunoglobulin M, and is called immunocytoma. Neurological complications are frequent, but encephalopathies due to lymphoplasmocytoid infiltration are rare (Bing-Neel syndrome). Tumors, probably arising from confluence of infiltrative areas, are exceedingly rare. The authors report the case of a 70-year-old man, suffering from a Waldenström's immunoglobulinemia, who underwent surgery for a right sided rolandic tumor involving the vault, the dura-mater, and the cortex. On the CT scan, the tumor mimicked a meningioma. Histological study and immunohistologic stains confirmed the monoclonal nature of the tumor. Based on the review of the literature, clinical and neuroradiological features of these infiltrative and tumoral rare lesions, as well as their histopathogenesis and treatment, are discussed.