morphological varients#downey cells#compaision with lymphoblast

1. ATYPICAL LYMPHOCYTES
Presented by:
Dr. Y L S

2. INTRODUCTION
 Morphological Varients Or Atypical/Reactive Lymphocytes
 Three Distinct Types Have Been Noted
 TYPE 1
 Plasmacytoid lymphocytes or turks irritation cells
 TYPE II
atypical Mononuclear cells/downey type II cells (IM)
 TYPE III
 Transformed /blastoid lymphocytes
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3. Type I Plasmacytoid Cells
 Differentiated cells that are functionally
incompetent and probably of B cell origin
 Size-9-20 um
 Shape –round to oval
 Cytoplasm is usually basophilic it may be
vacuolated with darker areas of basophilia at
the periphery.
 May contain azurophilic granules.
 Nucleus-dense blocks of irregularly clumped
chromatin .
 Nuclear shape may be oval or intended with
distinct nuclear membrane.
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4. Type II –Mononuclear Cells(IM)
 They are predominantly seen in infectious mononucleosis
 Size-15-25um
 Shape-irregular or scalloped margins(ballerina skirting)
 Cytoplasm-abundant and often intended .
 N/C ratio is 1:2 or 1:4
 Cytoplasm has vacuoles and usually pale except at the
periphery which is basophilic
 Nucleus-round to oval in shape coarse chromatin but not
condensed.
 Rounded masses of chromatin are interspersed
throughout ,nucleoli not visible
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5. Type III –Transformed Or blastoid Lymphocytes
 The process through which small lymphocyte
undergo blastic transformation
 Size-12-35um
 Shape-round to irregular
 Cytoplasm-vacuolated with abundant
basophilia and clear perinuclear area
 Nucleus-finely reticular nuclear chromatin
(immature Cells),loose indistinct clumping.
 Nucleoli are sometimes pesent
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6. Blastoid Lymphocyte Lymphoblast
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7. indices Blastoid lymphocyte lymphoblast
shape Round-irregular Round to oval
cytoplasm Moderate amount of
cytoplasm with vaculoations
Scanty basophilic cytoplasm
nucleus Fine reticular chromtin Coarse clumped chromtin with
indistinct nucleoli
nucleoli May/may not be present present
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8. Differntiation between atypical
lymphocyte and lymphoblasts
 Both atypical lymphocyte and lymphoblasts may exhibit immature looking like
cells.
 The major morphological differentiation lies in the heterogenity of the Variant
lymphocyte.
 Malignancies are clonal and all abnormal cells(blasts) appear very similar to one
another.
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9. Lymphoblasts seen in ALL 9

10. Atypical Lymphocytes In Dengue Fever
 The Atypical Lymphocyte count (AL) is a research parameter generated when a
Full Blood Count (FBC) is performed on Sysmex automated FBC analyzers.

 During dengue infection progression, it has been observed that affected patients
produced atypical lymphocytes seen in the peripheral blood circulation.
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11. 11
• These atypical lymphocytes have been identified as CD19+ B
lymphocytes using flow cytometry.(ref 03)
• It is postulated that these lymphocytes are antibody immune reaction
to the dengue virus, which could explain the significant increase in
anti-dengue immunoglobulin G (IgG) antibodies during the secondary
dengue infection.

12.  Recently, atypical plasmacytoid lymphocytes have been described in patients with
dengue infection, which similarly correlates to the significant elevation in IgG
levels.

 Atypical lymphocytes has been demonstrated to be useful for the differentiation of
dengue from other viral infections.

 Therefore, we seek to assess the association of Atypical lymphocytes with severity
of dengue infection.
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13. Plasmaytoid lymphocytes 13

14.  One more study done on dengue patients -data suggested that CD4, CD8, CD19
and CD69 were the markers of severity for dengue viral infection .(ref 04)
 They could be used to differentiate DHF from DF and DLS patients in the early
stage of disease.
 The depletion of CD4+ T cells is possibly due to their involvement in the immune
elimination mechanism, in response to dengue infection.
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15.  It is postulated that the atypical lymphocyte is an activated lymphocyte in
response to stimulation and expressed activation markers on the cell.
 The atypical lymphocyte was probably not trans- formed into a blast form, as
indicated by low percentage of TdT expressed cells.
 It is concluded that atypical lymphocyte and CD19+ cell counts should be
considered, besides platelets and white blood cell counts, as a useful diagnostic
tool for dengue infection.

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16. Atypical lymphocytes seen in dengue fever in paediatric
patient
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17. Photomicrograph of Blood Film At 100x (Leishman Stain) Showing Atypical Lymphocyte(13-8-21)
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18. Photomicrograph Of Buffy Coat Film At 100x (Leishman Stain) Showing Atypical Lymphocyte
Along With Normal Lymphocytes 18

19. Photomicrograph Of Buffy Coat Film At 100x (Leishman Stain) Showing Atypical
Lymphocyte With Cytoplasmic Vaculoations 19

20. REFERENCES
1. williams hematology 9th edition
2. dacie and lewis practical hematology 12th edition
3. Characterisation of atypical lymphocytes and immune
phenotypes of lymphocytes in patients with dengue viral
infection(APRIL 2007 ,launched by allergy and immunology
society of Thailand 25(1):27-36)
4. Plasmacytoid lymphocytes-a clue to dengue diagnosis.
Lagnajitha data, madhu P menon.blood (2017) 129
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