Professor Xu Wei: Diagnosis and Differential Diagnosis of CLL | The 4th China Conference on Chronic Lymphocytic Leukemia

The 4th China Chronic Lymphocytic Leukemia Conference and China Chronic Lymphocytic Leukemia Working Group Meeting, co-sponsored by the Hematology and Oncology Committee of the Chinese Anti-Cancer Association and the Hematology Hospital of the Chinese Academy of Medical Sciences, in 2021 It was successfully held in Tianjin from March 19th to 21st.

The conference took the form of a combination of offline and online, focusing on the basic and clinical translational research progress, hot issues and development trends of chronic lymphocytic leukemia.

At the meeting, Professor Xu Wei from the First Affiliated Hospital of Nanjing Medical University gave a special report on the diagnosis and differential diagnosis of chronic lymphocytic leukemia (CLL).
Yimaitong compiled the following for the reference of readers.

Professor Xu Wei, Chief Physician, PhD Supervisor, Deputy Director of the Department of Hematology, First Affiliated Hospital of Nanjing Medical University (Jiangsu Provincial People's Hospital), Deputy Chairman of the Hematology Oncology Committee of the Chinese Anti-Cancer Association, and Leader of the Lymphoma Group, China Association for Geriatric Lymphoma Professional Committee Vice Chairman CSCO China Anti-Lymphoma Alliance Standing Committee Member of the Standing Committee of the Chinese Society of Geriatrics Hematology Branch Member of the Standing Committee of the Chinese Women Physicians Association Standing Committee of the Hematology Professional Committee of the Chinese Society of Geriatric Oncology Member of the Lymphoma Professional Committee of the Chinese Anti-Cancer Association Member of the Lymphoma Professional Committee of China Member of the Experimental Hematology Professional Committee of the Pathophysiology Society Member and Secretary of the Integrated Hematology Professional Committee of the Chinese Medical Doctor Association Integrative Medicine Physician Branch Deputy Chairman of the Hematology Society of Jiangsu Medical Association Vice Chairman of the Lymphoma Professional Committee of Jiangsu Research Hospital Association Chairman of the Lymphoma Alliance, Vice Chairman of the Hematological Oncology Committee of Jiangsu Anti-Cancer Association, Member of the Standing Committee of the Lymphoma Professional Committee of Jiangsu Anti-Cancer Association, Vice Chairman of Nanjing Society of Hematology, Chinese Journal of Hematology, Chinese Journal of Experimental Hematology, and International Journal of Blood Transfusion and Hematology, "Leukemia·Lymphoma" and "BLOOD Chinese Edition" and other journals.
CLL is a lymphoproliferative disease derived from mature monoclonal B lymphocytes.

It mainly occurs in middle-aged and elderly people, and is characterized by the accumulation of lymphocytes in peripheral blood, bone marrow, spleen and lymph nodes.

Small lymphocytic lymphoma (SLL) is the same disease as CLL.
It is a non-leukemic manifestation of CLL, collectively referred to as CLL/SLL.

Diagnosis of CLL Professor Xu Wei said that with the increase in public health awareness, CLL is mostly found during physical examination.
The three criteria for diagnosis are as follows: Peripheral blood monoclonal B lymphocyte count ≥ 5×109/L.

(In the 2016 edition of the World Health Organization [WHO] tumor classification, when the peripheral blood monoclonal B lymphocyte count is less than 5×109/L, if there is no extramedullary disease, even if there are few blood cells or disease-related symptoms, it cannot be diagnosed as CLL.

However, the updated international CLL working group standards in 2018 still diagnose this condition as CLL.

) The International Chronic Lymphocytic Leukemia Working Group (iwCLL) "Chronic Lymphocytic Leukemia Diagnosis, Treatment Indications, Efficacy Evaluation and Supportive Treatment Guidelines (2018 version)” pointed out: Regardless of the number of peripheral blood B lymphocytes or lymph node involvement, cytopenias caused by typical bone marrow infiltration are diagnosed as CLL.

Professor Xu Wei said that this kind of situation is rare, but it should arouse everyone's attention.

Peripheral blood smears are characterized by a significant increase in small, mature lymphocytes, with less cytoplasm, dense nuclei, inconspicuous nucleoli, and partial aggregation of chromatin, and smear cells are easy to see.

Atypical lymphocytes and immature lymphocytes in peripheral blood lymphocytes ≤55%.

Typical flow cytometry immunophenotype: CD19+, CD5+, CD23+, CD200+, CD10-, FMC7-, CD43+/-; weak expression of surface immunoglobulin (slg), CD20 and CD79b (dim).

According to the immunophenotypic scores tested by flow cytometry (as shown in the table below), typical CLL scores are 4 to 5 points, 0 to 2 points can exclude CLL, and 3 points need to exclude other types of B-cell chronic lymphoproliferative diseases (B -CLPD).

In addition, bone marrow immunohistochemistry LEF1 can also help diagnose CLL.
LEF1 is only positive in CLL and negative in other B-cell lymphomas. Subsequently, Professor Xu Wei introduced the precursor disease of CLL/SLL-monoclonal B lymphocytosis (MBL).
The diagnostic criteria for MBL are as follows: B cell clonal abnormality; monoclonal B lymphocyte <5×109/L; No enlarged liver, spleen, and lymph nodes (lymph node length <1.
5cm); no anemia and thrombocytopenia; no other clinical symptoms of chronic lymphoproliferative disease (CLPD).

MBL has a variety of immunophenotypes, such as CLL phenotype, atypical CLL phenotype and non-CLL phenotype.

Professor Xu Wei emphasized that when patients have atypical CLL phenotypes or non-CLL phenotypes, comprehensive examinations (such as imaging, bone marrow biopsy, etc.
) are required to exclude non-Hodgkin's lymphoma in the leukemia stage.

If it is a CLL phenotype, patients with MBL with a high CLL cell count (CLL cells ≥0.
5×109/L) require regular follow-up.

CLL, MBL, and SLL have the same immunophenotype.
The following figure distinguishes these three concepts in detail: CLL differential diagnosis Next, Professor Xu Wei introduced the differential diagnosis of CLL and other B-CLPD in detail.

01CLL and MCL 80% of patients with mantle cell lymphoma (MCL) are in advanced stage (stage III/IV) at the time of diagnosis, 90% of MCL patients are often accompanied by extranodal spreading lesions, and 80% of MZL patients have MCL cells in the peripheral blood (flow The proportion of cytology is even higher, up to 92%).

The immunophenotype of mantle cell lymphoma (MCL) is characterized by CD5+, Cyclin D1+, and simultaneously expresses CD19, CD20, CD22, and CD79β.

The expression of CD20, slg and CD79β of MCL is stronger than that of CLL.

Most MCL patients are negative for CD23 (25% are weakly positive) and negative for CD11c.

CD23 has important value in distinguishing CLL and MCL: CD23 positive rate>92.
5% is CLL, <30% is MCL, 30%-92.
5% is more difficult to judge (as shown below). It can be further identified by CD148 and CD200: CD148 is weakly expressed in CLL and strongly expressed in MCL; CD200 is strongly expressed in CLL, but is negative in MCL (as shown in the figure below).

In addition, the abnormality of chromosome t(11;14)(q13;q32) leading to the translocation of CCND1 gene and immunoglobulin heavy chain (IGH) gene is considered to be the genetic basis of MCL, which is found in more than 95% of MCL patients, which can be helpful For MCL diagnosis.

02CLL and FL Professor Xu Wei said that it is easy to distinguish between follicular lymphoma (FL) and CLL.
The immunophenotypic characteristics of FL: express the whole B cell markers CD19, CD20, CD22, CD79α, FMC7 and germinal center antigen CD10, The fluorescence intensity of BCL2, BCL6, and CD20 belong to normal lymphocytes.
Some patients are CD23 positive and CD5 negative.

And 80% of FL patients have t(14;18)(q32;q21).

03CLL and SMZL splenic marginal zone lymphoma (SMZL) is often accompanied by a huge spleen, the germinal center of the splenic white pulp, the splenic hilar lymph nodes are invaded, the bone marrow and peripheral blood are often affected (the cell membrane is often accompanied by villous protrusions), superficial lymph nodes and Extranodal tissues are rarely involved.
Serum monoclonal immunoglobulin can be detected in 30%-40% of SMZL patients.

Professor Xu Wei emphasized that the way SMZL invades the bone marrow is usually intrasinusal invasion, and rarely is paratrabecular invasion.

SMZL has no specific antigen expression, so an exclusive diagnosis is required.
The minimum diagnostic criteria are as follows: spleen histology + CLL immunophenotypic score ≤ 2 points; if the spleen histology test results cannot be obtained, typical blood and bone marrow morphology + Immunophenotype + CD20-positive cell infiltration in the bone marrow sinus.

Professor Xu Wei said that in patients with splenomegaly, if the spleen histological test results are not available, the typical blood and bone marrow findings are sufficient for diagnosis.

04CLL and LPL/WM Lymphoid plasma cell lymphoma (LPL) is a malignant tumor composed of small B cells, plasma cell-like lymphocytes and plasma cells.

The bone marrow of Waldenstrom's macroglobulinemia (WM) is infiltrated with plasma cell-like lymphocytes, and monoclonal IgM is present in the serum.

MYD88 L265P mutation is the most common gene mutation in WM, but it should be noted that other lymphomas will also have MYD88 L265P mutation.

05CLL and HCL hairy cell leukemia (HCL) is mainly manifested by splenomegaly and few whole blood cells, and mononuclear cell reduction is the characteristic manifestation.

The bone marrow biopsy showed "fried egg-like" changes.

Cytochemical staining of tartrate-resistant acid phosphatase particles was strongly positive.

The immunophenotyping test showed strong positive for CD11c, CD20, etc.

Annexin A1 is one of the markers to identify HCL.
It is positive in HCL and negative in other B-cell lymphomas.

06CLL and B-PLL should exclude CLL with Richter transformation, CLL with proliferation of lymphocytosis, MCL blastocytosis, MZL with proliferation of proliferation, hairy cell leukemia variant (HCL-v), and peripheral blood proliferation of lymphocytes If the ratio of lymphocytes is ≥55%, it can be diagnosed as B-pilocytic leukemia (B-PLL).

Complex karyotypes are common in B-PLL patients, and 50% of patients have abnormal p53 genes.

Summary Finally, Professor Xu Wei summarized the differential diagnosis of B-CLPD (as shown in the figure below).

She emphasized that there is a type of B-CLPD in the clinic that still does not meet any of the above subcategories based on clinical characteristics, cell morphology, immunophenotype, cell/molecular genetics, etc.
, and can be diagnosed as B-CLPD-U.

Such patients should obtain as many histological specimens as possible for adequate diagnosis, such as lymph node biopsy, splenectomy biopsy, etc.

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