Brain Pathology Case of the Month - April 2018


Primary CNS Lymphoplasmacytic Lymphoma.


Other than diffuse large B-cell lymphoma, lymphomas manifesting primarily in the CNS are rare (1). They include low grade B-cell and T-cell lymphomas (3% of all CNS lymphomas), the majority are of B-cell lineage (2). Primary CNS low-grade B-cell lymphomas almost exclusively affect adults. Patients presents with seizures, visual defects, focal neurological findings, and/or memory impairment (1, 2). There is no association with immunodeficiency except in rare cases of extranodal marginal zone lymphoma (MALT lymphoma) (3). As one subgroup of low-grade B-cell lymphomas, primary CNS lymphoplasmacytic lymphomas (LPL) are even rarer. So far in the literature only 22 cases have been reported (4). Therefore, it is critical to confirm a neoplastic process, not a chronic inflammatory process. Meticulous staging to exclude a systemic lymphoma is also essential.

In terms of differential diagnoses, intraventricular tumors are rare lesions that make up 0.8%-1.6% of all intracranial tumors (5). They are however more common in children and comprise around 16% of childhood and adolescent intracranial tumors. These are a histologically heterogeneous group of tumors that can be divided into primary and secondary intraventricular tumors. "Primary tumors" are neoplasms that originate from the ependymal or subependymal lining (ependymoma, subependymoma, subependymal giant cell astrocytoma), septum pellucidum (central neurocytoma), choroid plexus (choroid plexus papilloma and carcinoma), and the supporting arachnoid tissue (meningioma). "Secondary or paraventricular tumors" is a term used when these neoplasms originate from adjacent brain substance and demonstrate more than two-thirds exophytic growth within the ventricle. Although the neuroimaging diagnosis may be challenging, it is in general not difficult to differentiate intraventricular lymphoma from other intraventricular neoplasms based on histologic examination. If there is any doubt, a lack of immunoreactivity to EMA, cytokeratin, GFAP, or synaptophysin will help distinguish the lymphoma apart.

Perhaps more diagnostically challenging, is to separate LPL from other low grade B-cell lymphoma, including small lymphocytic lymphoma, MALT lymphoma and follicular lymphoma. By definition, LPL does not fulfill the criteria for any of the other small B-cell lymphoid neoplasms that may have plasmacytic differentiation. Because the distinction between LPL and these other lymphomas, especially MALT lymphoma, is not always clear-cut, some cases may need to be diagnosed as a small B-cell lymphoma with plasmacytic differentiation and a differential diagnosis provided.

In general, the behavior of LPL is indolent and patients usually do well (1, 4). There are no set guidelines for treatment. Treatment has varied widely and has included complete or partial resection, steroids, radiation, chemotherapy, and combinations of these despite there is little evidence that adjuvant chemo or radiation would increase the chance of cure. Treatment is aimed at control of the disease process and prevention of end organ damage. There is no known benefit to early treatment when patients are asymptomatic or without organ impairment.


  1. Lim, T., et al., Primary CNS lymphoma other than DLBCL: a descriptive analysis of clinical features and treatment outcomes. Ann Hematol, 2011. 90(12): p. 1391-8.
  2. Jahnke, K., et al., Low-grade primary central nervous system lymphoma in immunocompetent patients. Br J Haematol, 2005. 128(5): p. 616-24.
  3. Ponzoni, M., et al., Central nervous system marginal zone B-cell lymphoma associated with Chlamydophila psittaci infection. Hum Pathol, 2011. 42(5): p. 738-42.
  4. Abbi, K.K., et al., Primary CNS lymphoplasmacytic lymphoma: a case report and review of literature. Hematol Oncol Stem Cell Ther, 2013. 6(2): p. 76-8.
  5. Agarwal, A. and S. Kanekar, Intraventricular Tumors. Semin Ultrasound CT MR, 2016. 37(2): p. 150-8.

Contributed by Fenghua Zhang, MD; Liam Chen, MD, PhD

International Society of Neuropathology