Classification

Lymphoblastic leukaemia, synonymous with acute lymphoblastic leukaemia (ALL) and lymphoblastic lymphoma (LBL), are overlapping clinical entities caused by lymphoblasts of T or B origin (precursor lymphoid neoplasms). The WHO Classification of Tumours of Haemopoietic and Lymphoid Tissues (2008, p168), states:

“By convention the term lymphoma is used when the process is confined to a mass lesion with no or minimal evidence of peripheral blood and bone marrow involvement. With extensive marrow and blood involvement, lymphoblastic leukaemia is the appropriate term. If the patient presents with a mass lesion and lymphoblasts in the bone marrow, the distinction between leukaemia and lymphoma is arbitrary. For many treatment protocols a figure of 25% BM blasts is used as the threshold for defining leukaemia.”

Precursor B-ALL is more common than T-ALL, accounting for >90% of paediatric and 75% of adult cases. T-LBL is more common than B-LBL, comprising >90% of lymphoma presentations.

These are the main types of precursor Acute Lymphoblastic Leukaemia recognised by the WHO Classification:

In contrast, Burkitt leukaemia is classified by WHO amongst Mature B-cell neoplasms as one presentation of Burkitt lymphoma. Burkitt lymphoma is treated differently from precursor lymphoid neoplasms and is covered in the Lymphoma chapter of this Red Book.


About this Canterbury DHB document (8842):
Document Owner:	Peter Ganly (see Who's Who)
Last Reviewed:	December 2021
Next Review:	December 2024
Keywords:
Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document. Disclaimer The Haematology Department Protocols and Guidelines (the Red Book) are intended as a guide for registered health professionals to communicate guidelines and share best practices with supporting health professionals within New Zealand district health boards. They are not intended to be provided to or used as a reference for patients or non-registered health professionals. All health professionals must exercise their own clinical judgement and use pertinent clinical data when treating patients. The authors and editors of this publication have checked with sources believed to be reliable in their effort to provide information that is complete and in accord with the standards accepted at the time of publication. However, in view of the possibility of human error or changes in medical science, neither the authors, editors, publisher, nor any other party who has been involved in preparing or publishing this work warrants that the information contained in it is accurate or complete in every respect. They therefore have no liability (whether in tort (including negligence) or otherwise) for any loss or damage arising out of any reliance on this information. This publication has been compiled by the staff and contractors of Canterbury District Health Board (CDHB) and as such CDHB has copyright for this book. Amendments must be authorised in accordance with the documented process. No release of part of, or all of, this publication to any other party or organisation is permissible without the prior approval of the designated document owner.
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