DefinitionOne of the confusing aspects of the lymphoid neoplasms concerns the use of the descriptive terms "lymphocytic leukemia and lymphoma.
Leukemia is used for lymphoid neoplasms presenting with widespread involvement of the bone marrow, usually accompanied by the presence of large numbers of tumor cells in the peripheral blood.
Lymphoma, on the other hand, is used to describe proliferations arising as discrete tissue masses. Traditionally, these terms were attached to what were felt to be distinct entities. However, the line between the "lymphocytic leukemias" and the "lymphomas" often blurs. Many types of "lymphoma" occasionally present with a leukemic peripheral blood picture accompanied by extensive marrow involvement, and evolution to "leukemia" is not unusual during progression of incurable "lymphomas." Conversely, tumors identical to "leukemias" sometimes arise as soft tissue masses without evidence of bone marrow disease. Hence, when applied to particular neoplasms, the terms "leukemia" and "lymphoma" merely describe the usual tissue distribution of the disease at the time of clinical presentation.