NON-MALIGNANT REACTIVE DISORDERS OF LYMPHOCYTES

1. NON-MALIGNANT REACTIVE
DISORDERS OF LYMPHOCYTES

2. History
1907 – Turk
 First describe lymphocytes in a patient whose disease had
been diagnosed as acute leukemia and later recovered.
 He describe cells as having an immature nucleus and
basophilic cytoplasm similar to that of a plasma cell.
1923 – Downey and McKinlay
 “Acute Lymphadenosis Compared with Acute Lymphatic
Leukemia”.
1967 – Wood and Frenkel
 Important morphologic and biochemical characteristics of
variant lymphocytes in various clinical entities.

3. Morphology of Variant or Reactive
Lymphocytes
• The most common important
feature of variant lymphocyte
morphology is the recognition
of its benign nature.
• These lymphocytes are normal
cells that have been altered as
a result of a normal response
to stimulus.
• Downey and McKinlay – classic
description of the reactive
lymphocyte.

4. Morphology of Variant or Reactive
Lymphocytes
• Three distict types:
o Type I
 Plasmacytoid lymphocyte or Turks’s irritation cells.
o Type II
 Infectious Mononucleosis (IM)
o Type III
 Transformed lymphocytes or Reticular lymphocytes

5. Morphology of Variant or Reactive
Lymphocytes
Type I – “Plasmacytoid lymphocyte” or “Turks’s irritation cells”.
• Differentiated cells that are functionally immunocompetent
and probably of B-cell origin.
• Size: 9 to 20 um diameter
• Shape: Oval to Round
• Nucleus: Heavy strands or dense blocks of chromation
irregularly clumped with sharp, small, defined areas of
parachromatin; nuclear shape may be intented or oval. Nucleus
membrane is distinct.
• Cytoplasm: Basophilia varies but usually the cytoplasm is
moderately basophilic. It may be vacuolated, with darker areas of
basophilia at the periphery. It may also have a foamy appearance
and may contain azurophilic granules.

6. Morphology of Variant or Reactive
Lymphocytes
Type II – “Infectious Mononucleosis (IM)”
• They are predominant in Infectious Mononucleosis.
• Size: 15 to 25 um in diameter
• Shape: Irregular or Scalloped
• Nucleus: The chromatin strands are coarse but not as
condensed as those of type I. Rounded masses of chromatin are
interspersed throughout. Nuclear shape is round or oval and is
rarely lobulated. Nuclear banding frequently is seen in EDTA
specimens. Nucleoli usually are not visible.
• Cytoplasm: Abundant and often indented by surrounding
structures. Nuclear:cytoplasmic ration is 1:2 to 1:4. The cytoplasm
has few vacuoles and usually is pale, except for basophilia at the
periphery of the cytoplasm and radiating from the nucleus. This cell
often has been describe s resembling a friend egg or a flattered
skirt.

7. Morphology of Variant or Reactive
Lymphocytes
Type III – “Transformed lymphocytes” or “Reticular lymphocytes”
• Cells in intermediate stage of transformation, the process
through which the resting small lymphocyte undergoes blast
transformation and ultimately becomes a fully immunocompetent
T lymphocyte or plasma cell.
• Size: 12 to 35 um in diameter
• Shape: Round to irregular
• Nucleus Finely reticulated nuclear chromatin (immature).
Chromatin strands are finely dispersed with loose, indistinct
clumping and poorly defined parachromatin. Nucleoli are usually
highly visible and elongated or irregular in shape.
• Cytoplasm: Vacuolated with abundant basophilia and a clear
perinuclear area.

8. Lymphocyte Transformation
• The lymphocyte morphology describe reflects
the cumulative events following the antigenic
stimulation in which the stimulated
lymphocyte undergoes structural and
biochemical changes, transforming the small
lymphocytebto the blastlike-cell, the process
is called blastogenesis.
• Transformation can be produced in vitro by a
specific and non-specific antigens.

9. Lymphocyte Transformation
• Non-specific antigens used to stimulate
lymphocyte in vitro:
 Phytohemagglutinin (PHA)
 Pokeweed Mitogen (PWM)
 Streptolysin S Staphylococcus Endotoxin (SLS)
 Antilymphotcyte Globulin (ALG)
• Most commonly used are: PHA and PWM for
both T and B cell stimulation leading to mitosis.
 Cultures in using PHA show nucleolar changes in 4
hours and RNA production within 8 hours; at the end
of 72 hours most cells are transformed and in mitosis.

10. Lymphocyte Transformation
• Transmission Electron Microscope
 Nucleus becomes larger and clearer.
 Cytoplasm contains enlarge Golgi Apparatus.
 Ribosome increase in number.
 Mitochondria increase in volume.
 Endoplasmic Reticulum develops slightly.
 Azurophilic granules increase in number.
 Nucleoli become elongated and enlarged.
• Scanning Electron Microscope
 Reveals a pronounce shape change from round to “hand
mirror” shape.
 Uropod becomes very prominent.

11. Differentiation between Reactive and
Malignant Lymphocytes
• Both reactive and malignant lymphocytosis
may exhibit immature looking cells.
• The major morphologic differentiation lies in
the heterogeneity of the variant lymphocytes
(polymorphism).
• Malignancies are clonal, and all abnormal cells
appear very similar to the other one.

12. Absolute Lymphocytosis with Variant
Lymphocyte Morphology

13. Absolute Lymphocytosis with Variant
Lymphocyte Morphology
• Infectious Mononucleosis
 A clinical acute contagious viral disease that
affects primarily young adults and teenagers.
 Self-limited and benign, but serious complications
can occur which occasionally may be fatal.
 Characterized by variant (reactive) lymphocytes in
the peripheral blood and heterophil antibody-
positive serologic test.

14. Absolute Lymphocytosis with Variant
Lymphocyte Morphology
• History:
 1885 – Filatov – idiopathiclymphadenopathy in children.
 1889 – Pfeiffer – lymphatic reaction in children.
 1920 – Sprunt and Evans – used the term “Infectious
Mononucleosis”.
 1923 – Downey and McKinlay – morphology of the reactive
lymphocytes.
 1932 – Paul and Bunnell – Serologic characterization.
 1955 – Davidsohn and coworkers – refined serologic
characterization.
 1964 – Epstein. Anchong and Barr – herpes-like virus (EBV-
Epstein Barr Virus)

15. Absolute Lymphocytosis with Variant
Lymphocyte Morphology
• Clinical Features:
 Incubation period of IM is about 11 days.
 Fever, pharyngitis, and cervical lymphadenopathy are
presenting symptoms in more than 80% of cases.
 Splenomegaly is found in 50% of cases and hepatomegaly in
approximately 10% of patients.
 Rash is present in 20% of cases.
 Complications are pneumonitis, meningoencephalitis,
pericarditis, myocarditis, hepatitis, and laryngeal edema, all
of which are related to lymphocytic infiltrates.
 Neurologic syndromes such as Bell’s palsy and Guillain-Barre
usually are reversible.
 Clinical complications include hemorrhage due to
thrombocytopenia, airway obstruction due to enlargement
of pharyngeal lymphoid tissue, and splenic rupture is
splenomegaly is present.

16. Absolute Lymphocytosis with Variant
Lymphocyte Morphology
• Cytomegalovirus Infection
• Definition and Clinical Features:
 It is a disease caused by cytomegalovirus that closely
resembles IM.
 Most CMV infections appear to be subclinical.
 Fever and Splenomegaly are common in middle-aged
adults.
 Hematomegaly may be found in 50% of patients and a
rash may be present.
 Illness, malaise, fever and chills are common,
symptoms may persist for longer period (3 weeks)
 Incubation period is 35 to 40 days in adults, and 20 to
25 days for children.

17. Absolute Lymphocytosis with Variant
Lymphocyte Morphology
• Pathophysiology:
 The virus is found in urine, oral and cervical secretions,
and semen, as well as in leukocytes.
 Transmission in adults is primarily venereal.
 More than half of adults possess antibodies to CMV.

18. Absolute Lymphocytosis with Normal
Lymphocyte Morphology

19. Absolute Lymphocytosis with Normal
Lymphocyte Morphology
• Acute Infectious Lymphocytosis
• Usually found in children between ages of 1 to 10 years,
and occasionally up to 14 years of ages.
• It is contagious, benign, and self-limited.
• Causative agent maybe viral or non-viral.
• The incubation periods appears to be between 12 to 20
days.
• The disease lasts from 3 to 5 weeks and may last as long as
2 months.
• Clinical Features:
 Asymptomatic – patients with infectious lymphocytosis
 Symptoms accompany the disease are fever, upper respiratory
infection, diarrhea, and abdominal pain.

20. Absolute Lymphocytosis with Normal
Lymphocyte Morphology
• Bordetella Pertussis Infection
 Infection in which 79 to 90% of leukocytes on the
peripheral blood film are normal looking lymphocytes.
 The increase in small lymphocytes maybe due to
redistribution from tissue pools to circulating pools
caused by a lymphocyte-promoting factor (LPF).
 The leukocytosis and lymphocytosis are pronounced
than in any other febrile illness except IM.

21. Absolute Lymphocytosis with Normal
Lymphocyte Morphology
• Lymphocytic Leukemoid Reaction
 Any condition in which the lymphocytic
leukocytosis is so marked that it gives impression
of possible leukemia qualifies as a lymphocytic
leukemoid reaction.
 Infectious Mononucleosis in children may present
with leukocyte counts in excess of 50x109/L, which
may lead to an impression of acute lymphocytic
leukemia.

22. Relative Lymphocytosis with Variant
Lymphocyte Morphology

23. Relative Lymphocytosis with Variant
Lymphocyte Morphology
• Toxoplasmosis
 Toxoplasma (Toxoplsma gondii) infection is similar in
clinical presentation to IM, causing fever and enlarged
lymph nodes.
 The result of the heterophil antibody test is negative.
 Laboratory features are benign, with normal
hematologic parameters, the exception being a
relative increase in lymphocytes and the presence of
reactive lymphocytes.
 Current test for confirmatory are indirect fluorescent
antibody and indirect hemagglutination techniques.

24. Relative Lymphocytosis with Variant
Lymphocyte Morphology
• Miscellaneous Disorders
 Lymphopenia and neutropenia
 10% of patients with thyrotoxicosis have
neutropenia and relative lymphocytosis. The
blood probably due to disturbance of
adrenocortical function.

25. Relative Lymphocytosis with Normal
Lymphocyte Morphology
• Neutropenia
 Wide variety of conditions in which the absolute
number of neutrophils decreases, leaving relative
lymphocytosis in which lymphocyte morphology is
normal.