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Benign White Cell Disorders: Qualitative Disorders
| Qualitative or morphologic abnormalities of leukocytes may be hereditary
or acquired, permanent; or transient.
Hypersegmentation, the presence of abnormally increased nuclear
lobulation, is one of the first hematologic abnormalities seen in megaloblastic
anemia. Normal mature circulating neutrophils have an average of 3 lobes
and always fewer than 5 lobes. Eosinophils have fewer than 4 lobes and
basophils have fewer than 3 lobes. More than 3 cells having 5 lobes
or a single cell with 6 lobes found in the course of a 100 cell differential
is evidence of hypersegmentation. Hypersegmentation is sometimes referred
to as a myeloid "right shift". Hypersegmentation may accompany other
disorders in which there is a disturbance of maturation, such as iron
defiency. |
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| Myeloperoxidase deficiency (MPO) is a common (1:2,000 individuals)
autosomal recessive absence of myeloperoxidase enzyme in neutrophil
and monocyte granules. Although people with concommittant MPO deficiency
and diabetes mellitus may develop Candidiasis, MPO deficiency in most
people is of no clinical consequence.
Acquired MPO deficiency may be seen in acute myeloid leukemia, myelodysplastic
syndromes, and lead poisoning.
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| MPO Deficiency: |
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| 1)Wright's stained neutrophil; |
2)MPO stained neutrophil; |
3)MPO stained eosinophil; |
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Pelger-Huet anomaly is a congenital autosomal dominant disorder in
which granulocyte nuclei fail to segment normally. In the homozygote state
the nucleus is round. In heterozygotes most granulocytes have bilobed
nuclei ("pince-nez" cells) resembling bands. The trait is benign and occurs
in 1 in 6,000 people. Cell function is normal. |
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| An acquired or pseudo-Pelger-Huet anomaly is seen in myelodysplastic
disorders and following drug therapy, and may accompany leukemia
and certain infections. |
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| Toxic granulation is found in severe inflammatory states.
The toxic granules are azurophilic, usually found in the promyelocyte,
metamyelocyte, band, and segmented stages. The toxic granulation is
thought to be due to impaired cytoplasmic maturation,in the effort to
rapidly generate large numbers of granulocytes. |
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L Dohle bodies are single or multiple blue cytoplasmic
inclusions. They represent remnants of rough endoplasmic reticulum from
earlier maturational stages. They are associated with myeloid "left
shifts" and are seen in conjunction with toxic granulation.
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May-Hegglin anomaly is a rare autosomal dominant abnormality
characterized by large pale basophilic inclusions resembling Dohle bodies
and appear to be altered RNA. Giant platelets, and sometimes thrombocytopenia
are associated with this. The anomaly is usually benign but may be associated
with bleeding.
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The Chediak-Higashi syndrome is a rare autosomal recessive condition
associated with abnormally large leukocyte granules resulting from fusion
of lysozymes. This disorder may affect granulocytes, leukocytes, and monocytes.
Chemotaxis and phagocytosis is defective. Platelets lack dense granules
and platelet function is abnormal. Giant melanosomes in occular and skin
tissues result in hypopigmentation.
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The Alder-Reilly anomaly is associated with the genetic mucopoly-
saccharidoses. Patients with mucopolysaccharidoses lack the lysozymal
enzymes necessary to break down mucopolysaccharides. Dense azurophilic
granules, resembling toxic granulation in neutrophils, are seen in all
leukocytes. Most characteristic of these disorders are the metachromatic
granules surrounded by a clear zone seen in lymphocytes.
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As you can see, qualitative and quantitative evaluations of leukocytes
are useful 1) to establish diagnoses, 2) to prognosticate, and 3) to evaluate
therapy. You should now be aware of the major causes and mechanisms,
and clinical manifestations of leukocytoses and leukocytopenias. You
should also recognize the major morphologic white cell abnormalities
and know their clinical significance. |
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Pathology
> Basic Hematology > White
Cell Disorders > Benign White Cell Disorders: Qualitative Disorders
