Q. Does WBC count of 40000 suggest leukemia?

Answered by
Dr. Prakash H Muddegowda
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on May 08, 2017 and last reviewed on: Aug 19, 2019

Hello doctor,

What would you think if you see a WBC count as 40000 on CBC findings? Is it enough to think about leukemia or lymphoma? What is the difference between leukemia and leukemoid reaction? Please explain.



Welcome to

Based on your query, my opinion is as follows:

  • A count of 40000 is not high enough to think of leukemia on an immediate basis and leukemoid. The standard definition says count should be more than 50000 and should be caused by reactive causes outside the bone marrow.
  • If you really need to discuss between leukemia and leukemoid reaction in the absence of any clinical history or clinical findings, then in CBC (complete blood count), look for a platelet count.
  • If low, then think of acute leukemias and if normal, then no need for elaboration. Without a proper clinical history difficult to rule out leukemoid reaction.
  • Then need to order the next easy thing, peripheral smear to look for any immature cells or atypical cells. If present, then leukemia or lymphoma spill over, depending on the type of cells and the blast percentage.
  • Next depending on lymph node enlargement, lymph node FNAC (fine needle aspiration cytology) or biopsy the need will arise to go for bone marrow biopsy to do the actual blast percentage or atypical cell evaluation.
  • If morphology of cells are insufficient, then need to go into markers for evaluation of leukemia according to the WHO - World Health Organization classification. Both the flow cytometry and cytogenetics are necessary.
  • When you are specifically talking about lymphoblastic leukemia or lymphomas, TdT (terminal deoxynucleotidyl transferase), CDs (cluster of differentiations) and cytoplasmic mu chains play a role. The practical way is looking at the maturity of each cell.
  • At each stage, they express different markers indicating the cell type and the stage of development. You need to look into specific CD markers.
  • Any book dealing with lymphomas, will usually indicate what markers are expressed in various stages. There are over 350 markers and you can go about looking into basic important markers in identifying the cells.

For further information consult a hematologist online -->

Thank you doctor,

I would like to know the diseases that can be diagnosed by morphology alone and the diseases that always need immunotyping or gene typing for confirmation. The algorithm you suggested was awesome. I would also like to have one for myeloid leukemias, if possible.



Welcome back to

Based on your query, my opinion is as follows:

  • If you look into the recent WHO classification of any leukemia or lymphoma, it is based on morphology, cytochemistry, immunophenotyping and cytogenetics.
  • Morphology is always first, which the FAB classification (French-American-British classification) is based on.
  • These malignancies based on FAB classification like AML (acute myeloid leukemia) M0-M7 and L1-L3 are based on morphology. However, this is grossly alone inadequate for treatment purposes, towards which the WHO classification is leaning on.
  • For WHO classification, there is no specific algorithm, compared to lymphomas as they are based on a combination of morphology, immunophenotyping and cytogenetics.
  • Both prognosis and treatment choice for AML patients are based on the presence or absence of specific genetic alterations, which determine AML classification in three risk based-categories: Favorable, intermediate, and unfavorable. This classification is usually based on cytogenetic information.

For further information consult a hematologist online -->

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