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A woman doctor talks to an older man patient on a couch about SLL cancer.

Small lymphocytic lymphoma is a slow-growing cancer of the lymphatic system that affects B lymphocytes, which are specialized white blood cells that produce antibodies to help protect the body from infection. Cancerous B cells are not as effective at fighting off infection as healthy B lymphocytes, and over the course of time, they can crowd out their healthy counterparts. This makes a person with small lymphocytic lymphoma more susceptible to developing serious health conditions.

Also known as SLL lymphoma or well-differentiated lymphocytic lymphoma, this type of cancer affects the same kind of cells that chronic lymphocytic leukemia does—the only difference is where those cells are located. In the case of SLL lymphoma, the cancerous B cells are primarily found in the affected person’s lymph nodes and lymphoid tissues, such as the spleen. If a person has chronic lymphocytic leukemia, the cancerous B cells are mostly in the bloodstream and bone marrow. In 2016, the World Health Organization classified these two cancers as essentially the same disease.

Although the word “chronic” is not in the name, SLL is a type of non-Hodgkin lymphoma that develops slowly and might not cause any symptoms for many years. Contrast this to “acute” forms of lymphoma, which are highly aggressive.

Additionally, unlike many acute forms of lymphoma and leukemia, SLL develops far more often in adults than children. Considered a rare disease at any age, this type of lymphoma seldom occurs in people younger than 50.

Causes and risk factors of small lymphocytic lymphoma

It’s not yet fully understood what causes any type of cancer to develop. However, as with other types of cancer, lymphoma develops because of genetic mutations at the cellular level. In the case of SLL, the result is abnormal B lymphocytes that multiply uncontrollably and eventually crowd out the normal B cells. Although cancer researchers don’t know exactly what causes the genetic changes that lead to SLL lymphoma, they have evidence that it’s not a hereditary condition passed from parents to children.

When discussing risk factors for any disease, it’s important to note that simply having the identified risk factors does not mean a person will develop the associated health condition. Nor does not having those risk factors necessarily mean a person won’t develop the disease. SLL lymphoma is rare, but people may have a higher risk of developing it if:

  • They’re older adults. The average age for an SLL diagnosis is 65.
  • They’ve had chemotherapy, which weakens the immune system.
  • They’ve been infected with HIV, the virus that causes AIDS, or have another condition that weakens the immune system.
  • They’ve had extensive exposure to pesticides and herbicides.

What’s more, men have a somewhat higher risk of developing this type of lymphoma than women.

Small lymphocytic lymphoma symptoms

This type of lymphoma often causes no symptoms, even in the later stages. The only signs of it may be the abnormalities that show up in a routine blood test.

However, for those who experience symptoms, the signs may include:

  • Swelling in the lymph nodes of the armpit, neck or groin
  • Unintended weight loss
  • Fever that’s unaccompanied by an infection
  • Night sweats
  • Fatigue                                                                                         
  • Shortness of breath
  • Unexplained bruising
  • A swollen belly area
  • Feeling full after eating only a small amount of food

Diagnosing SLL lymphoma

A physician or pathologist may suspect the presence of small lymphocytic lymphoma after a common blood test known as a comprehensive blood count (CBC) analysis turns up certain anomalies. A physician may also order testing for lymphoma based on a patient’s symptoms or the discovery of a swollen lymph node.  

A lymph node biopsy is usually required to diagnose SLL lymphoma. For this test, a physician removes one of the patient’s lymph nodes and sends a tissue sample to a lab for expert analysis by a trained pathologist. If an SLL lymphoma diagnosis is confirmed, the patient may then undergo bone marrow aspiration and biopsy procedures to find out how advanced the cancer is. These procedures are usually performed at the same time and involve using needles to withdraw samples of bone marrow from a patient’s hip bone for analysis.

SLL lymphoma treatment

As with other types of nonagressive lymphoma, asymptomatic SLL patients may at first receive ongoing monitoring of their condition, including getting periodic testing to determine whether the disease is progressing. If they develop symptoms or if testing indicates that more aggressive treatment is called for, some common therapies include:

  • Steroids, to treat autoimmune symptoms
  • Chemotherapy, on its own or combined with immunotherapy drugs or radiation therapy
  • Targeted therapies, such as monoclonal antibodies and Bruton Tyrosine Kinase (BTK) inhibitors
  • Supportive care, which could include blood or platelet transfusions
  • Stem cell transplantation
  • Clinical trials

The Moffitt Cancer Center difference for SLL patients

Moffitt is not only Florida’s top cancer hospital but also a nationally recognized cancer center that’s at the forefront of both groundbreaking cancer research and innovations in patient care. Our Malignant Hematology Program, which is dedicated to treating cancers of the blood and bone marrow, is a shining example. Our team includes highly specialized hematologists who are experienced at diagnosing and treating even rare types of cancer like small lymphocytic lymphoma.

Moreover, our patients benefit from our individualized approach to cancer care, in which a multispecialty team regularly assesses each patient’s condition and collaborates to create the most effective treatment plan possible. And our status as the only National Cancer Institute-designated Comprehensive Cancer Center based in Florida gives our patients access to clinical trials and other novel cancer treatments that are not widely available at other institutions.

Perhaps the best reason to choose Moffitt first for cancer care is our sense of urgency. Whether you’re seeking an initial diagnosis, a second opinion or cancer treatment, you will be a top priority of a cancer center that delivers nationally-ranked care in new and transformative ways. Call 1-888-663-3488 today or use our online new patient registration form, and we’ll make sure to connect you with a cancer expert within a day of your inquiry. No referral is needed to visit Moffitt.


Lymphoma Research Foundation – CLL/SLL
Healthline – Understanding Small Lymphocytic Lymphoma and How It’s Treated
Verywellhealth – Small Lymphocytic Lymphoma: Overview and More