How is pediatric non-Hodgkin lymphoma (NHL) differentiated from acute leukemia?

Updated: Jun 14, 2018
  • Author: J Martin Johnston, MD; Chief Editor: Max J Coppes, MD, PhD, MBA  more...
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Childhood non-Hodgkin lymphoma generally manifests as bulky extramedullary (usually extranodal) disease with or without demonstrable dissemination. Particularly in the case of lymphoblastic diseases, the distinction between non-Hodgkin lymphoma and acute leukemia is arbitrary. Therefore, these entities (acute lymphoblastic leukemia and lymphoblastic lymphoma) are best considered in terms of a spectrum ranging from clinically localized disease to overt leukemia.

In most treatment protocols, acute leukemia is now defined on the basis of marrow involvement above some threshold (typically, a blast count of >25%) irrespective of the presence of bulky extramedullary disease. In contrast, an extramedullary tumor accompanied by marrow involvement below this threshold constitutes stage 4 lymphoma. The term, "leukemia/lymphoma syndrome," which was once in common usage, is no longer valid.

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