Splenic lymphoma (SL)

Overview of splenic marginal zone lymphoma (SMZL)

Splenic marginal zone lymphoma (SMZL) is an indolent (slow growing) non-Hodgkin lymphoma (NHL). SMZL is rare, accounting for around 1% of all NHLs. Most patients have an enlarged spleen and abnormal blood cell counts. 

The spleen is an organ that is part of the immune system and is one of the organs of the lymphatic system. The spleen is involved in fighting infections, is a filter for the blood, destroys old red blood cells and stores white blood cells and platelets. It is usually around the size of a pear and sits in the upper left-hand side of the abdomen to the left of the stomach.  When the spleen is enlarged it might feel like a lump at the top of your stomach.  

It can sometimes affect the lymph nodes of the abdomen (stomach), but in most cases splenic MZL does not affect the lymph nodes.

Splenic MZL is an indolent (slow growing) lymphoma and treatments are used to keep the lymphoma under control, rather than to cure it.  There are some good treatments for splenic MZL, and it can be controlled for many years with several courses of treatment. 

What is the spleen?

Who is affected by splenic marginal zone lymphoma (SMZL)?

Splenic marginal zone lymphoma (SMZL) is a rare form of lymphoma, involving the spleen, bone marrow and often the blood. It affects both men and women, although more common in men, and it most common in people who are middle aged or elderly, with the average age at diagnosis of 65 years.  It is uncommon before the age of 50 years.

It is not usually clear why splenic MZL develops, although it has been associated with people who have been diagnosed with the hepatitis C virus (HCV) or other autoimmune disorders.    However, it is important to note that NOT all people diagnosed with these will go on to develop splenic MZL.

Symptoms of splenic marginal zone lymphoma (SMZL)

The most common symptom of splenic marginal zone lymphoma (SMZL) is an enlarged spleen (splenomegaly), that the doctor may notice that it is bigger than it should be during a physical examination of the stomach or  abnormal cells are found  when  a blood test is done for another reason.  There is usually involvement of the blood and bone marrow at the time of diagnosis, with the only other symptom being fatigue.

When the spleen is enlarged it might feel like a lump at the top of the stomach and may cause a feeling of a full stomach, even after small meals, and/or abdominal pain or discomfort.  The doctor may be able to feel that the spleen is enlarged when they feel the abdomen. An enlarged spleen may also mean it is not functioning properly. This can cause anaemia and thrombocytopenia and this is discussed in more detail below.

The bone marrow is the spongy tissue in the centre of bones where blood cells are made. If lymphoma cells build up in the bone marrow it may not be able to make enough blood cells. This in addition to the spleen not functioning properly can lead to:

• Anaemia: a shortage of red blood cells which may cause tiredness and/or short of breath 
• Thrombocytopenia: a shortage of platelets which may cause bleeding or bruising more easily

Some people with splenic MZL produce abnormal proteins that clump together especially when it is cold, these are called ‘cryoglobulins’.  This can lead to poor circulation, headaches, confusion, nosebleeds and blurred vision.

Another group of symptoms called B symptoms can include:

• Night sweats (drenching sleepwear or bedding)
• Persistent fevers (especially at night >38C)
• Unexplained weight loss

It is important the doctor is aware of all symptoms as it can influence the decision around the type of treatment and when to start.

Diagnosis and staging of splenic marginal zone lymphoma (SMZL)

Splenic marginal zone lymphoma (SMZL) can be difficult to diagnose.  It can look similar to other types of lymphoma, such as Waldenstrom’s macroglobulinemia.  It can be diagnosed using a combination of blood tests and a bone marrow biopsy. 

• Blood tests to check blood cell counts and look for abnormal lymphocytes and antibodies in your blood

• A Bone marrow biopsy is a procedure that involves taking a sample of bone marrow, usually from the hip bone. The biopsy is generally done using a local anaesthetic. The doctors will remove a small amount of liquid from inside the bone marrow and a small core of bone to test for the presence of lymphoma. 

 The doctor may also suggest an operation to remove an enlarged spleen and it is called a ‘splenectomy’. It is possible to live without a spleen, but precautions are needed to help prevent and fight off infections. 

Waiting for results can be a difficult time.  It may help to talk to family, friends, or a specialist nurse.

Staging of splenic marginal zone lymphoma (SMZL) 

Once a diagnosis of SMZL is made, further tests are required to see where else in the body the lymphoma has affected or is located.  This is called staging. The staging of the lymphoma helps the clinician decide the best treatment 

There are four stages from stage 1 (lymphoma in one area) through to stage 4 (lymphoma that is widespread). 

•  Early stage means stage 1 and some stage 2 lymphoma.  This can also be referred to as ‘localised’.  Stage 1 or 2 means that the lymphoma is found in one area or a few areas close together.
• Advanced stage means the lymphoma is stage 3 and stage 4, and it is widespread.   In most cases, the lymphoma has spread to many parts of the body that are far from each other.  

What is the ‘grade’ of splenic MZL 

Lymphomas are also often grouped as either indolent (slow growing)or aggressive (fast growing). The grade is also referred to as the clinical behaviour of the lymphoma. It is important to know the stage and grade of the lymphoma to determine the best treatment.

Staging scans and tests

The scans and tests needed for staging and before treatment can start may include:

• Positron emission tomography (PET) scan 
• Computed tomography (CT) scan 
• Bone marrow biopsy 
• Lumbar puncture & magnetic resonance imaging (MRI) – If lymphoma is suspected in the brain or spinal cord

Patients may also undergo a number of baseline tests prior to any treatment commencing to check organ functions.  These are often repeated during and after the treatment has completed to assess whether the treatment has affected the functioning of organs.  Sometimes the treatment and follow-up care may need to be adjusted to help manage side effects. These may include:

•  Physical examination
•  Vital observations (blood pressure, temperature, & pulse rate)
•  Heart scan
•  Kidney scan
•  Breathing tests
•  Blood tests

It may take some time for all the necessary biopsies and tests to be done (an average of 1-3 weeks), but it is important for the doctors to have a complete picture of the  lymphoma and the general  health of the patient  in order to make the best treatment decisions.

Many of the staging and organ function tests are done again after treatment to check whether the lymphoma treatment has worked and the effect this has had on the body.

Splenic MZL is a low-grade lymphoma.  Most people have advanced disease at diagnosis as the bone marrow is usually affected. Effective treatment is available to treat advanced splenic MZL. The doctor will use the results of the biopsy, staging and baseline tests to choose the best treatmen