ABCL-006: High Grade Primary Bone Lymphoma with TdT Expression

Abstract

Context Distinguishing mature B-cell lymphomas from immature or precursor B-cell neoplasms is important since different treatments are usually given. It is known that some mature B-cell neoplasms can have relatively immature morphologic features and present similarly to a leukemia. Expression of TdT in lymphomas that are typically negative for TdT can occur rarely and present a diagnostic challenge. This entity can present de novo or in the setting of a relapsed/refractory lymphoma, usually follicular lymphomas. Primary bone lymphoma, characterized by exclusive bone or marrow involvement, represents less than 2% of all lymphomas in adults. Its frequency is lower in children and young adults. Objective To describe a case of a high-grade primary bone lymphoma with TdT expression. Setting A 35 yo man was admitted for severe bone pain, fever, and night sweats. Laboratory showed no abnormalities; HIV, HCV, and HBV serologies and blood cultures including atypical germs were negative. Magnetic resonance showed disseminated bone lesions predominant in column and pelvis. Bone marrow biopsy showed an infiltration by a CD20, CD 10 BCL2 positive high grade B cell lymphoma. MUM1 and TdT were negative. He initiated treatment with R-DA-EPOCH presenting refractory disease after 3 cycles: PET/CT uptake in both clavicles, humerus, scapula, dorsolumbar raquis, iliac bones and ribs. Max SUV was 20 in the 7th right rib. A new biopsy was done which result was consistent with an infiltration by a B cell neoplasm with 2 different populations: both positive for CD10, PAX5, BCL2 and one positive for TdT and CD20 while the other was CD20 and TdT negative. High-grade lymphoma and areas of a B cell lymphoblastic like neoplasm expressing TdT was the final diagnosis. His treatment was changed to R Hyper-CVAD plus triple intrathecal chemotherapy, and he is currently undergoing that treatment. Consolidation with allogeneic marrow transplant is planned. Summary/Conclusion TdT positive neoplasms diagnostic is challenging. Whether this case represents a composite neoplasm (high grade lymphoma with lymphoblastic leukemia/lymphoma) or if it is a transformation from a previous asymptomatic lymphoma is a matter of debate. Distinguishing mature B-cell lymphomas from immature or precursor B-cell neoplasms is important since different treatments are usually given. It is known that some mature B-cell neoplasms can have relatively immature morphologic features and present similarly to a leukemia. Expression of TdT in lymphomas that are typically negative for TdT can occur rarely and present a diagnostic challenge. This entity can present de novo or in the setting of a relapsed/refractory lymphoma, usually follicular lymphomas. Primary bone lymphoma, characterized by exclusive bone or marrow involvement, represents less than 2% of all lymphomas in adults. Its frequency is lower in children and young adults. To describe a case of a high-grade primary bone lymphoma with TdT expression. A 35 yo man was admitted for severe bone pain, fever, and night sweats. Laboratory showed no abnormalities; HIV, HCV, and HBV serologies and blood cultures including atypical germs were negative. Magnetic resonance showed disseminated bone lesions predominant in column and pelvis. Bone marrow biopsy showed an infiltration by a CD20, CD 10 BCL2 positive high grade B cell lymphoma. MUM1 and TdT were negative. He initiated treatment with R-DA-EPOCH presenting refractory disease after 3 cycles: PET/CT uptake in both clavicles, humerus, scapula, dorsolumbar raquis, iliac bones and ribs. Max SUV was 20 in the 7th right rib. A new biopsy was done which result was consistent with an infiltration by a B cell neoplasm with 2 different populations: both positive for CD10, PAX5, BCL2 and one positive for TdT and CD20 while the other was CD20 and TdT negative. High-grade lymphoma and areas of a B cell lymphoblastic like neoplasm expressing TdT was the final diagnosis. His treatment was changed to R Hyper-CVAD plus triple intrathecal chemotherapy, and he is currently undergoing that treatment. Consolidation with allogeneic marrow transplant is planned. TdT positive neoplasms diagnostic is challenging. Whether this case represents a composite neoplasm (high grade lymphoma with lymphoblastic leukemia/lymphoma) or if it is a transformation from a previous asymptomatic lymphoma is a matter of debate.