What is the Difference Between CLL and SLL

The key difference between CLL and SLL is that CLL is a type of Non-Hodgkin’s lymphoma where abnormal B cells accumulate mostly in blood and bone marrow, while SLL is a type of Non-Hodgkin’s lymphoma where abnormal B cells accumulate mostly in lymph nodes.

Lymphoma is a cancer that begins by infecting the lymphocytes, the fighting cells of the immune system known as. These cells are in the lymph nodes, spleen, thymus, bone marrow, and other parts of the body. Generally, in lymphoma, the lymphocytes change and grow out of control. There are two main types of lymphoma: Non-Hodgkin and Hodgkin. CLL and SLL are two Non-Hodgkin’s types of lymphomas.

1. Overview and Key Difference
2. What is CLL
3. What is SLL
4. Similarities – CLL and SLL
5. CLL vs SLL in Tabular Form
6. Summary – CLL vs SLL

What is CLL (Chronic Lymphocytic Leukemia)?

Chronic lymphocytic leukemia (CLL) is a cancer of the blood and bone marrow. In CLL, abnormal B cells accumulate mostly in blood and bone marrow. The term chronic in chronic lymphocytic leukemia comes from the fact that this disease normally progresses more slowly. The term lymphocytic indicates the type of cells usually affected (a group of white blood cells known as lymphocytes). CLL most commonly affects older adults, and it is a type of Non-Hodgkin lymphoma.

Many people who are diagnosed with CLL have no symptoms at first. The common signs and symptoms of CLL might include enlarged and painless lymph nodes, fatigue, fever, pain in the upper left portion of the abdomen (due to enlarged spleen), night sweats, weight loss, bleeding and bruising more easily, high temperature, anemia, shortness of breath, pale skin, and frequent infections.

Figure 01: CLL

In most cases, the exact cause of CLL is not known. But most probably, it is due to a mutation of DNA of blood-producing cells. It is more likely to follow risk factors such as the family history of CLL, middle-aged or older, white men, and relatives who are either East European or Russian Jews.

Moreover, CLL can be diagnosed through blood tests, imaging tests such as CT scans and PET scans, bone marrow biopsies, lymph nodes biopsies, and genetic tests. Furthermore, treatments for CLL include chemotherapy (fludarabine, rituximab), radiotherapy, stem cells or bone marrow transplant, surgery to remove the swollen spleen, antibiotics, antifungals, antivirus drugs for reducing infections, blood transfusion, immunoglobulin replacement therapy, and injecting a medicine called granulocyte stimulating factor (G-CSF) to help boost white blood cells.

What is SLL (Small Lymphocytic Lymphoma)?

Small lymphocytic lymphoma (SLL) is a type of Non-Hodgkin’s lymphoma where abnormal B cells accumulate mostly in lymph nodes. It is also a slow-growing cancer. This condition affects men more than women. SLL is typically seen in older adults (the average age diagnosed is 65). The symptoms of SLL may include painless swelling in the neck, armpit, and groin, fatigue, unexplained weight loss, fever, night sweats, swollen, tender belly, feeling of fullness, shortness of breath, easy bruising, and skin lesions.

The exact cause of SLL is not known. It may be due to a DNA mutation of blood-producing cells. The risk factors for SLL include older age, family history, weak immune system (HIV infection), previous chemotherapy, long-term exposure to certain pesticides, and exposure to radon at home.

Figure 02: SLL

Moreover, SLL can be diagnosed by physical examination, lymph node biopsy, and bone marrow tests such as (bone marrow aspiration and biopsy). Furthermore, SLL can be treated with chemotherapy, monoclonal antibody therapy (alemtuzumab, brentuximab, ibritumomab tiuxetan, obinutuzumab), radiation therapy, targeted drug therapy (acalabrutinib, ibrutinib, duvelisib, idelalisib), and stem cell therapy.

What are the Similarities Between CLL and SLL?

CLL and SLL are two blood cancers.
They are Non-Hodgkin types of lymphomas.
In both cancer types, B cells are affected.
Both cancers are most probably due to a mutation in the DNA of blood-producing cells.
They are slow-growing.
Both cancers predominately affect older adults.
They are treatable through chemotherapy, radiation, and stem cell therapy.

What is the Difference Between CLL and SLL?

CLL is a type of Non-Hodgkin’s lymphoma where abnormal B cells accumulate mostly in the blood and bone marrow, while SLL is a type of Non-Hodgkin’s lymphoma where abnormal B cells accumulate mostly in lymph nodes. Thus, this is the key difference between CLL and SLL. Furthermore, a person with CLL will have more than 5000 monoclonal lymphocytes per cubic millimetre (mm³). On the other hand, a person with SLL will have less than 5000 monoclonal lymphocytes per cubic millimetre (mm³).

The following table summarizes the difference between CLL and SLL.

Summary – CLL vs SLL

CLL and SLL are two Non-Hodgkin’s types of lymphomas. In CLL, the abnormal B cells accumulate mostly in blood and bone marrow, while in SLL, the abnormal B cells accumulate mostly in lymph nodes. So, this is the summary of the difference between CLL and SLL.

Reference:

1. “What Is Chronic Lymphocytic Leukemia?” American Cancer Society.
2. “Small Lymphocytic Lymphoma (SLL): Causes, Symptoms, Treatment, and More.” WebMD.

Image Courtesy:

1. “Chronic lymphocytic leukemia” By VashiDonsk at the English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
2. “Small Lymphocytic Lymphoma in Marrow (5078628812)” By Ed Uthman from Houston, TX, USA – Small Lymphocytic Lymphoma in MarrowUploaded by CFCF (CC BY 2.0) via Commons Wikimedia