2. Leukemoid reaction
• Secondary reversible marked increase of WBC count
>50000/cumm in response to a stimulus & immature
WBCs(blasts<5%) in peripheral blood resembling
leukaemia
• Seen in non leukemic conditions
3. Causes
Myeloid leukemoid reaction Lymphoid leukemoid reaction
Severe bacterial infection
e.g – Pneumonia, endocarditis,
Septicemia & cellullitis
Viral infections : IMN, chicken pox,
mumps, scarlet fever
Severe acute hemolysis Bacterial infections : TB, syphilis
Cancer metastatic to bone marrow
Others : eclampsia, burns, mercury
poisoning
Eosinophilic leukemoid reaction
Allergic states – asthma, urticaria
Parasitic diseases
5. Differential diagnosis
Parameters Leukemoid
reaction
CML CNL
Age Any age Middle age Elderly
C/F As per
underlying cause
Splenomegaly + Hepatoslpenomegal
y
RBC Anaemia
minimal
Severe &
progressive
normal
TLC >50,000/cumm 50,000 -
morethan 1
lakh/cumm
> 25,000/cumm
LAP score Increased Decreased High
Cytogenetics nil BCR- ABL fusion BCR- ABL (-) &
CSF3R mutation(+)
Extra
medullary
myeloid
tumours
Absent Present Absent
6. Parameter Laekemoid reaction CML CNL
Peripheral smear Leukocytes of
mature forms, shift
to left , with
toxic granules
More immature
forms with basophilia
& eosinophilia.
Marked neutrophilia
with Pro myelo, meta
myelo & myelocytes
(<10%),
Band forms &
segmented forms
(>80%)
Bone marrow Hyper cellular
Myeloid hyperplasia,
orderly maturation
Markedly
Hypercellular with
Slight incraese in
blasts,
Pseudo gaucher cells
Hypercellular &
packed bone marrow
with increased
neutrophils,
myeloblast <5%
10. Lymphoid leukemoid reaction
• Main differential is CLL/SLL
Parameters Lymphoid leukemoid
reaction
CLL
Age Any age > 60yrs
Onset Acute Insidious
Peripheral smear Reactive atypical lymphocytes Small lymphocytes,
Smudge cells
Clinical course Self limiting Progressive
11.
12. Differentiation of leukaemoid reaction from
leukaemia
1. Clinical presentation
2. Presence of underlying condition
3. Morphology of blood smear
4. % of blasts in bone marrow
5. Correction of leukaemoid picture after treatment
of underlying disease
13. Leukoerythroblastic reaction
• Presence of immature neutrophil series & nucleated
red cells in peripheral blood
• WBC count – Normal/high
• Anaemia & high RDW
• Due to disturbance in bone marrow architecture
• This is known as myelophthisic anaemia
14. Mechanism
Two major mechanisms
- Altered marrow- blood barrier due to marrow
infiltration
- Extra medullary haematopoiesis as a
compensatory response to bone marrow stress
16. • RBC – Anisopoikilocytosis hypochomia
TEAR DROP cells, polychromasia
NRBCs
Retic Count (3-10%)
• WBC – Normal / Increased / Reduced
Shift to left
• Platelets - Normal / Reduced / Increased in
myelofibrosis abnormally large
• Bone marrow biopsy is necessary in all cases for definitive
diagnosis