Prolonged Enhancement of a Demyelinating Lesion Mimicking Lymphoma

Background: Primary Central Nervous System Lymphoma (PCNSL) is characterized as a rare group of non-Hodgkin's Lymphoma, typically of B-cell origin, whose incidence has increase over the last three decades. Albeit, the main risk for PCNSL has been immunodeficiency recent studies have published reports that the incidence among immune competent patients has increased (Schlegel 2009  and Villano 2011).  Typically PCNSL has magnetic resonance imaging (MRI) findings similar to MRI findings for demyelinating diseases. PCNSL can present as unifocal or multifocal homogeneous enhancing lesions on MRI (Zhang 2011).  We present the case of 61 year-old Caucasian female with one year history of relapsing remitting multiple sclerosis that was being treated with interferon beta 1a who on routine brain MRI had a new enhancing lesion that was suspicious for neoplasm.  The lesion’s enhancement pattern persisted for over 6 months. She had repeat lumbar punctures for cerebrospinal fluid (CSF) analysis. She had flow cytometry of her CSF which revealed a slight proliferation of B-cells initially but subsequent CSF analysis was inconclusive. Repeated brain MRI and MR spectroscopy continued to reveal an enhancing lesion concerning for neoplasm. Eventually after six months her enhancement resolved.

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Conclusions: Currently there is limiting diagnostic criteria and/or testing to help discern changes on MRI that are suggestive on PCNSL in patients with demyelinating diseases. Immunocompromised and immunodeficiency are the main risk factors for PCNSL and frequently patients with demyelinating diseases are treated with chemotherapy drugs. PCNSL incidence is increasing in immunocompetent patients. This case history and imaging represents the need for better diagnostic testing in patients with demyelinating diseases who have changes that are concerning for PCNSL.