INNV-41. SUCCESSFUL TREATMENT OF EXTREMELY RARE CASE OF PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOPLASMACYTIC LYMPHOMA WITH BENDAMUSTINE-RITUXIMAB REGIMEN: A CASE REPORT

Lymphoplasmacytic lymphoma (LPL) is an uncommon low-grade non-Hodgkin B-cell lymphoma, with an annual incidence rate of 3 to 4 cases per million people. Primary central nervous system lymphoplasmacytic lymphoma (PCNSLPL) is even rarer, with fewer than 30 cases documented in the literature so far, to our knowledge. We report a case of a 40-year-old Caucasian male who presented with headaches and mild short-term memory problems. CT was suggestive of a right parietal mass. MRI revealed a right parietal homogeneously contrast-enhancing mass with T2 and flair changes extending to the right lateral ventricle, suggestive of vasogenic edema. An open biopsy was performed, and immunohistochemical analysis of the sample indicated lymphoplasmacytic lymphoma. PET scan was negative for hypermetabolic lesions. Bone marrow biopsy, serum protein electrophoresis, urine protein electrophoresis, and CSF analysis were unremarkable. A diagnosis of primary central nervous system lymphoplasmacytic lymphoma (PCNSLPL) was given after comprehensive workup. Treatment with 10 cycles of bendamustine and rituximab (BR regimen) resulted in a good response. The patient has been clinically stable and improving for over a year. Radiologically, there has been interval shrinkage of the right parietal mass and follow-up scans continue to be stable. The plan is to continue maintenance rituximab for 2 years. Although extremely rare, PCNSLPL should be considered in differential diagnoses of hematolymphoid tumors of the CNS and bendamustine with rituximab as induction treatment followed by maintenance rituximab might be considered.