Page 369 - Textbook of Pathology, 6th Edition

Myeloid Leukaemoid Reaction absence of infiltration by immature cells in organs and 353
CAUSES. Majority of leukaemoid reactions involve the tissues.
granulocyte series. It may occur in association with a wide Table 14.3 sums up the features to distinguish myeloid
variety of diseases. These are as under: leukaemoid reaction from chronic myeloid leukaemia.
1. Infections e.g. staphylococcal pneumonia, disseminated
tuberculosis, meningitis, diphtheria, sepsis, endocarditis, Lymphoid Leukaemoid Reaction
plague, infected abortions etc. CAUSES. Lymphoid leukaemoid reaction may be found in
2. Intoxication e.g. eclampsia, mercury poisoning, severe the following conditions:
burns. 1. Infections e.g. infectious mononucleosis, cytomegalovirus
3. Malignant diseases e.g. multiple myeloma, myelofibrosis, infection, pertussis (whooping cough), chickenpox, measles,
Hodgkin’s disease, bone metastases. infectious lymphocytosis, tuberculosis.
4. Severe haemorrhage and severe haemolysis. 2. Malignant diseases may rarely produce lymphoid
leukaemoid reaction.
LABORATORY FINDINGS. Myeloid leukaemoid reaction
is characterised by the following laboratory features: LABORATORY FINDINGS. The blood picture is CHAPTER 14
1. Leucocytosis, usually moderate, not exceeding 100,000/ characterised by the following findings:
μl. 1. Leucocytosis not exceeding 100,000/μl.
2. Proportion of immature cells mild to moderate, 2. The differential white cell count reveals mostly mature
comprised by metamyelocytes, myelocytes (5-15%), and lymphocytes simulating the blood picture found in cases
blasts fewer than 5% i.e. the blood picture simulates of CLL.
somewhat with that of CML (Fig. 14.10, A).
3. Infective cases may show toxic granulation and Döhle HAEMATOLOGIC NEOPLASMS
bodies in the cytoplasm of neutrophils.
(LEUKAEMIAS-LYMPHOMAS): GENERAL
4. Neutrophil (or Leucocyte) alkaline phosphatase (NAP or LAP)
score in the cytoplasm of mature neutrophils in leukaemoid CLASSIFICATION: CURRENT CONCEPTS
reaction is characteristically high and is very useful to
distinguish it from chronic myeloid leukaemia in doubtful Neoplastic proliferations of white blood cells— leukaemias
cases (Fig. 14.10, B). and lymphomas, are the most important group of leucocyte
5. Cytogenetic studies may be helpful in exceptional cases disorders.
which reveal negative Philadelphia chromosome in Historically, leukaemias have been classified on the basis
myeloid leukaemoid reaction but positive in cases of CML. of cell types predominantly involved into myeloid and
6. Additional features include anaemia, normal-to-raised lymphoid, and on the basis of natural history of the disease, Disorders of Leucocytes and Lymphoreticular Tissues
platelet count, myeloid hyperplasia of the marrow and into acute and chronic. Thus, the main types of leukaemias
have been: acute myeloblastic leukaemia and acute lymphoblastic

Figure 14.10 Leukaemoid reaction. A, Peripheral blood film showing marked neutrophilic leucocytosis accompanied with late precursors of
myeloid series. B, Neutrophil (or leucocyte) alkaline phosphatase (NAP or LAP) activity is higher as demonstrated by this cytochemical stain.