Lymphoblastic lymphoma is a rare variant of non-Hodgkin lymphoma. From which cell lineage does the vast majority originate?

• A. B cells
• B. T cells
• C. Natural killer cells
• D. Plasma cells

Answer: (B)

Lymphoblastic lymphoma is a high-grade tumor made of lymphoblasts, the very early precursors of lymphocytes. Among the lymphoid lineages, these malignant lymphoblasts most commonly arise from the T-cell pathway. These precursor T cells develop in the thymus, so when they become cancerous they frequently form a mediastinal mass, especially in children and young people. Immunophenotyping often shows immature T-cell markers, such as TdT positivity with CD3 and CD7, supporting the T-cell origin. B-cell lymphoblastic lymphoma does occur but is much less common, while natural killer lineage and plasma cells are not the typical source of lymphoblastic lymphoma.