A Rare Case of B Lymphoblastic Lymphoma Arising From Leptomeninges

Lymphoblastic lymphoma and acute lymphoblastic leukemia (ALL) are precursor B- or T-cell neoplasms associated with aggressive clinical course. B-lymphoblastic lymphomas (B-LBL) account for only 10% of lymphoblastic lymphomas, with remaining 90% having T-cell origin. Less than 25% lymphoblasts in bone marrow and primary involvement of extranodal sites are considered criteria for calling B-LBL versus B-ALL. B-LBL is more common in patients younger than 18 years old, and has slight male predominance. Less than 100 cases of B-LBL have been reported in literature. We report the case of a 34-year-old man who had presented to outside hospitals complaining of headaches. He was treated for different diseases of infectious and noninfectious etiology, including viral meningitis. A flow cytometry analysis on CSF sample showed 36% of cells being positive for CD19, CD20, CD10, CD34, TdT, cytoplasmic CD22, CD38, and HLA-DR. CSF smear showed small to medium-sized blasts, which together with immunophenotypes, is consistent with B-ALL or B-LBL. He was transferred to our institution and underwent bone marrow procedure which showed hypocellular marrow, and 5% tumor cells in bone marrow positive for CD19, CD38, HLA-DR, and partially positive for CD20 (28%), CD34 (19%), and TdT (7%). Fluorescence in situ hybridization for ALL was negative and cytogenetic analysis results were normal. The PET scan for showed hypermetabolic leptomeningeal lymphomatous involvement of lumbar spine and no other suspected sites identified. Therefore, a diagnosis of B-LBL was made. He is currently undergoing intrathecal methotrexate with systemic Hyper C-VAD alternated with Ara-C methotrexate therapy. Herein, we describe extremely rare occurrence of B-LBL primarily involving the leptomeninges. An accurate diagnosis for this rare entity requires information from various sources including CSF sample, bone marrow aspirate with biopsy, flow cytometry, and PET imaging. To the best of our knowledge, this is the second reported case of primary leptomeningeal B-LBL.