What is abnormal lymphadenopathy?

foreword

Foreword Foreword

With the rapid development of modern medicine, the automation of medical laboratory detection technology has greatly improved its detection ability, but at the same time, for some diseases that depend on the identification of cell types, microscopy is still used as the "gold standard" for laboratory examinations
.
Today, we will take you through the small cases in our daily work to lift the veil of abnormal lymphatic variability

.

case after

case by case by case

On the last day of 2021, I will receive pictures of cell morphology under the microscope after Wright's staining, the classification and counting of blood cell analyzers, and the scatter diagram of the instrument sent by my colleague's WeChat
.
It is reported that the patient is an adult male.

He came to the emergency department due to cold symptoms and abdominal pain.

Figure 1 Morphology of two types of atypical lymphocytes under the microscope by Rigg staining

Fig.
1 Morphology of two types of atypical lymphocytes under the microscope by Riggi stainingFig.
1 Morphology of two types of atypical lymphocytes by Rigg staining under the microscope

At the same time, several lymphocytes were found that were slightly larger than normal lymphocytes, with deviated nuclei, thick chromatin, rich dark blue cytoplasm, and many small vacuolar cells
.
Isn't this type I and type II atypical lymphocytes?

Look at the blood cell analysis and test results: WBC 25.
83×109/L, MON% 22.
0%, PLT 35×109/L, two lines are high, one line is low, and the proportion of monocytes is very high (Figure 2).
Part of the gray area of ​​monocytes is confluent and rises obviously, (Figure 3).
See the figure below for details:

Figure 2 Differential count of cells on hemocytometer

Fig.
2 Differential counting of cells on hemocytometerFig.
2 Differential counting of cells on hemocytometer

Figure 3 Abnormal scatter plot of hemocytometer

Fig.
3 Abnormal scatter plot of hemocytometerFig.
3 Abnormal scatter plot of hemocytometer

According to the found cell morphology and instrument classification and counting information, it is speculated that the atypical lymphocytes of this patient should be far more than 10% under the microscope
.
It is found that there are two types of atypical lymphocytes at the same time, and blood system diseases are not considered.

Is such a high number of atypical lymphocytes an EB virus infection?

It is the "culprit" that causes infectious mononucleosis, commonly known as "leaflet".
Children are susceptible, and the patient is an adult.
Combined with the symptoms of cold and abdominal pain, and the low platelet count, it is winter and popular Hemorrhagic fever is more likely, because the disease progresses rapidly and the mortality rate is high, so I immediately contacted colleagues in the department with my thoughts
.

After discussion, my colleague's idea coincides with mine, and the two-type atypical lymphocyte count under the microscope accounts for about 35%.
After communicating with the clinician, it is recommended that the patient should be additionally tested for epidemic hemorrhagic fever antibody, urine routine and emergency renal function
.

Epidemic hemorrhagic fever antibody IgG and IgG were positive after investigation; urine routine results: urine occult blood 1+, protein 3+, 63 red blood cells/uL, pathological casts 6/uL; emergency renal function: creatinine 163.
0umol/L, Urea nitrogen 11.
3umol/L
.
It meets the diagnostic requirements of laboratory examinations and immunological examinations for epidemic hemorrhagic fever.

From the issuance of morphological critical values ​​to the reporting of other laboratory positive results such as epidemic hemorrhagic fever antibodies, it takes only half an hour before and after.

Morphological science

Morphology Popularization Morphology Popularization

Lymphocytes are generally classified into three types according to their properties: normal lymphocytes, atypical lymphocytes, and abnormal lymphocytes
.

normal lymphocytes, atypical lymphocytes, abnormal lymphocytes normal lymphocytes, atypical lymphocytes, abnormal lymphocytes

Atypical lymphocytes are habitually called virus cells, infectious monocytes, stimulatory lymphocytes, etc.
Atypical lymphocytes are occasionally seen in the blood of normal people (normal value is 0-2.
0%), only when a large number of virus infections, protozoa infections or connective tissue disease, the proportion of these cells is increased, so it is also called reactive lymphocytes
.

Atypical lymphocytes in peripheral blood > 5% have clinical significance, and when the increase is > 10% to 20%, it is more valuable for diagnosis
.
The generation mechanism of heterotypic lymphocytes is that the virus binds to B lymphocyte receptors.

During the process of continuous proliferation and replication, it is recognized by T lymphocytes, which stimulates the proliferation of suppressor T cells (Ts/c) and transforms itself, resulting in cytotoxicity.

Atypical lymphoids have various forms, usually enlarged cell bodies, increased cytoplasm, strong basophilicity, and nucleoblastization in blood smears
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According to the morphological characteristics are divided into three types

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Vacuole type (type I): also known as foam type or plasma cell type, the cell body is slightly larger than normal lymphocytes, mostly round, with rich cytoplasm, dark blue, no particles, containing vacuoles of different sizes or Foamy, nuclei are round, oval, kidney-shaped or irregular, and chromatin is coarse reticulate or irregularly aggregated in rough lumps
.

Atypical lymphocytes (type II): also known as mononuclear cell type.
Figure 2 belongs to this type.
The cell body is enlarged, the shape is irregular, the nucleus is round or irregular, and the chromatin is aggregated but still loose and small.
Rich in quality, light blue or blue, with a sense of transparency, uneven coloring, dark blue at the edge, skirt-like, may have a few azurophilic particles, generally no vacuoles
.

Naive type (type III): The cell body is larger, the cytoplasm is less, dark blue, mostly without granules, occasionally small vacuoles, the nucleus is large, the chromatin is round or oval, and the chromatin is finely reticulated, and there may be 1- 2 nucleoli
.

Atypical lymphocytes (reactive lymphocytes) are a type of benign cells, while abnormal lymphocytes are malignant clonal cells (such as lymphoma cells, leukemia cells), and it is easy to confuse the two in our clinical work.
Lymphocytes are diverse, and it is easy to see more than two forms under the microscope, while abnormal lymphocytes are often highly homogeneous and generally have a single form under the microscope.
If we only see one of them, we need to be vigilant to avoid misdiagnosis
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Only by memorizing the structure of normal lymphocytes can we correctly distinguish and help diagnose the disease

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case analysis

case study case study

"epidemic hemorrhagic fever", also known as hemorrhagic fever with renal syndrome, is a common infectious disease in northern winter
.
It is caused by Hantavirus and is a natural foci of disease with rodents as the main source of infection

.

Laboratory tests include:

Laboratory tests include: Laboratory tests include:

1.
Blood routine: most of the white blood cell counts are normal on the 1st and 2nd day of the disease course, and gradually increase after the third day of the disease, reaching (15-30) × 109/L, and a few severe patients can reach (50-100) × 109/L, In the early stage, neutrophils increased, the nucleus shifted to the left, and there were toxic granules.
In severe patients, immature cells showed leukemia-like reaction
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After the 4th to 5th day of illness, lymphocytes increased, and more atypical lymphocytes appeared

.
Due to plasma extravasation and hemoconcentration, hemoglobin and red blood cell counts increased from the late stage of fever to the hypotensive shock period, and platelets began to decrease from the second day of illness, and atypical platelets were seen
.

2.
Urine routine: Urinary protein can appear on the second day of the course of the disease, and the urinary protein often reaches (+++) ~ (++++) on the 4th to 6th disease day.
The sudden appearance of a large amount of urine protein is very helpful for diagnosis
.
In some cases, membranes appear in the urine, which are aggregates of large amounts of urine protein mixed with red blood cells and exfoliated epithelial cells
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Microscopic examination showed red blood cells, white blood cells and casts.
In addition, huge fusion cells could be found in the urine sediment, which was the fusion of exfoliated cells of the urinary system caused by the envelope glycoprotein of hantavirus under acidic conditions.
These fusion cells could be detected Hantavirus antigen
.

3.
Blood biochemical examination: BUN and creatinine began to increase in the hypotensive shock stage and in a few patients in the late stage of fever, peaked at the end of the transition stage, and began to decline in the late stage of polyuria
.
Respiratory alkalosis was more common in blood gas analysis during the fever phase, and metabolic acidosis was the main symptom during the shock and oliguria phases
.
Serum sodium, chloride, and calcium decreased in most stages of the disease, while phosphorus and magnesium increased
.
Serum potassium increases during the oliguria period, but a small number of patients still have hypokalemia during the oliguria period
.
Liver function tests showed elevated transaminases and elevated bilirubin
.

4.
Coagulation function test: thrombocytopenia begins in the fever period, and its adhesion, aggregation and release functions are reduced.
If DIC occurs, the platelets often decrease to less than 50 × 109/L.
In the hypercoagulable period of DIC, the coagulation time is shortened, and consumptive hypocoagulation occurs.
In the stage of hyperfibrinolysis, fibrinogen decreased, prothrombin time and thrombin time prolonged, and fibrin degradation products (FDP) increased in the hyperfibrinolysis stage
.

Etiological diagnosis includes:

Etiological diagnosis includes: Etiological diagnosis includes:

1 Immunological examination

1 Immunological examination

Specific antibody detection: specific IgM antibody can be detected on the second day of illness, 1:20 is positive; IgG antibody, 1:40 is positive
.
A 4-fold or more rise in titer after 1 week is diagnostic
.
Commonly used detection methods include indirect immunofluorescence and IgM antibody capture ELISA (MacELISA)
.
In recent years, colloidal gold technology has been developed for the detection of anti-Hantaan virus IgM and IgG antibodies.
The IgM-captured colloidal gold-labeled test strip can be used for rapid detection in 5 minutes to interpret the results.
The sensitivity is comparable to ELISA, but the specificity is slightly worse
.

Cellular immunity: The CD4+/CD8+ ratio of peripheral blood lymphocyte subsets decreased or inverted
.
In terms of humoral immunity, serum IgM, IgG, IgA and IgE were generally increased, and total complement and sub-complement C3 and C4 were decreased, and specific circulating immune complexes could be detected
.

2 Molecular testing

2 Molecular testing

The nested RT-PCR method can detect hantavirus RNA with high sensitivity and diagnostic value
.

Infectious mononucleosis (IM), referred to as leaflet, is an acute lymphocytic proliferative infectious disease caused by Epstein-Barr virus infection
.
The disease is mainly in children, and it is rare in adolescents and adults
.
The main route of transmission is droplet transmission
.
The incubation period of the disease is 5 to 15 days.
The onset varies rapidly and slowly.
The symptoms are diverse, including fever, angina, and lymphadenopathy.
A small number of patients have hepatosplenomegaly, jaundice, rash, and polyneuritis
.
Leaflet diagnostic points: typical clinical manifestations include fever, angina and lymphadenopathy, peripheral blood atypical lymphocytes > 10%, serum heterophilic agglutination test (+), positive EB virus IgM antibody detection and EB virus DNA quantitative increase
.

Cytomegalovirus (CMV) is a herpes virus, and the population is generally susceptible.
Among congenital viral infections, cytomegalovirus infection is the most common
.
The infected mother infects the fetus through the placenta, and the child may develop jaundice, hepatosplenomegaly, thrombocytopenic purpura, hemolytic anemia and hepatitis, etc.
The acquired infection is acquired in the form of contact transmission
.
The clinical manifestations are similar to those of leaflets, but the clinical symptoms are milder than those of leaflets, the ratio of atypical lymphocytes is less than that of leaflets, the severity of hepatosplenomegaly and hepatitis is not as severe as that of leaflets, and the heterophagocytosis agglutination test is negative
.

The clinical manifestations of this patient, the proportion of mononuclear cells in the blood routine increased significantly, and the proportion of atypical lymphocytes was 35%, which was very similar to the leaflet, but was related to the patient's age, urine protein, renal function indicators, low platelet count and virus antibodies.
Laboratory tests were used as the basis for differential diagnosis to support an epidemic hemorrhagic fever infection
.

Case experience

case experience case experience

From this case, we have realized the value of atypical lymphocytes increased to varying degrees in viral infectious diseases such as leaflet, Hantavirus (the pathogen of epidemic hemorrhagic fever), cytomegalovirus, herpes virus, and influenza virus
.
Morphological differential diagnosis is the "gold standard" of laboratory examination.
Only by mastering the morphological characteristics and diagnostic criteria of cells can we propose reasonable and effective laboratory examination recommendations for clinical practice, and fully reflect the clinical value of current examiners
.

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