CD 5+ Peripheral B Cell Lymphoma With Transformation to CD 5+ Diffuse Large B Cell Lymphoma in the CNS: A Case Report Treated With Rituximab, High Dose Methotrexate, Cytarabine, and Intrathecal Methotrexate

B-cell non-Hodgkin’s lymphoma includes several subtypes, notably Diffuse Large B-Cell Lymphoma (DLBCL), the most common B-cell subtype. Each presentation has its defining characteristic, of which CD5 positivity is notoriously known for being a poor prognostic factor. CD5 positivity has a high female preponderance, more commonly involves the bone marrow, presents with higher LDH levels and B symptoms on presentation, and stage 3-4 on the diagnosis. The exact incidence of CD5+ DLBCL arising from Chronic Lymphocytic Leukemia (CLL) is not explicitly defined in the literature, but it can be expected in about 5-10% of cases on average. Our patient is a 52-year-old female with no previous history of malignancy who presented with bilateral lower extremity weakness progressing to paraplegia and was found to have a CD5+ B-cell lymphoma in the peripheral blood with a CD5+ Diffuse Large B-cell lymphoma in the central nervous system (CNS). Treatment consisted of Rituximab, High dose Methotrexate (HD-MTX), and Cytarabine/intrathecal Methotrexate for CNS involvement for four cycles. Our patient tolerated therapy with improved neurological symptoms and no evidence of blasts on her peripheral smear or malignant cells on Cerebral Spinal Fluid Flow Cytometry after treatment. Her presentation and response to treatment highlight a possible treatment scheme for this rare and aggressive disease subtype.