Lymphoma is a type of cancer that originates in lymphocytes, white blood cells that are part of the body’s immune system. These cells normally circulate throughout the lymphatic system, helping to fight infections. Splenic lymphoma is a less common subtype of lymphoma, distinguished by its primary site of origin: the spleen, an organ located in the upper left abdomen. This form often affects the spleen, bone marrow, and blood.
Understanding Splenic Lymphoma
Splenic lymphoma primarily involves abnormal B-lymphocytes that collect in the spleen. This condition is classified as a slow-growing, or indolent, non-Hodgkin lymphoma. The most common type is Splenic Marginal Zone Lymphoma (SMZL), which accounts for less than 2% of all non-Hodgkin lymphoma cases. Other rare variants, such as Hairy Cell Leukemia (HCL) variant, are also categorized under splenic B-cell lymphoma.
SMZL develops from B cells in a specific area of lymphoid tissues called the marginal zone. Unlike many other lymphomas, SMZL does not cause swollen lymph nodes, though it can involve the bone marrow and circulating blood. Its indolent nature means it may progress gradually over many years, contrasting with more aggressive lymphomas that develop and spread rapidly.
Recognizing Symptoms
Symptoms associated with splenic lymphoma stem from an enlarged spleen, known as splenomegaly. The spleen can become significantly larger, leading to discomfort or pain in the upper left abdomen, sometimes radiating to the left shoulder. This enlargement can also cause a feeling of fullness after eating small amounts of food, as the spleen may press on the stomach.
Beyond localized discomfort, individuals may experience systemic “B symptoms,” which include unexplained fevers, drenching night sweats, and unintentional weight loss. Other signs include fatigue, often linked to anemia (a shortage of red blood cells), and an increased susceptibility to infections due to low white blood cell counts. These symptoms occur as lymphoma cells accumulate in the spleen and potentially the bone marrow, interfering with the production and function of healthy blood cells.
Diagnostic Approaches
Diagnosing splenic lymphoma begins with initial blood tests, such as a complete blood count (CBC), which may reveal abnormal levels of red blood cells, white blood cells, or platelets. These cytopenias, or low blood cell counts, can result from an enlarged spleen removing too many blood cells or lymphoma cells crowding out healthy cells in the bone marrow. Imaging studies, including ultrasound, computed tomography (CT) scans, and positron emission tomography (PET) scans, assess the spleen’s size and determine if other lymph nodes or organs are involved. A normal spleen size on imaging does not rule out lymphoma, as diffuse infiltrative disease might only present as an enlarged spleen.
A definitive diagnosis relies on a bone marrow biopsy, where a sample of bone marrow is taken to check for lymphoma cells. This procedure helps determine the percentage of abnormal cells in the bone marrow. Flow cytometry, a laboratory technique, is performed on blood or bone marrow samples to identify specific cell surface markers on the neoplastic cells, aiding in lymphoma classification. This analysis helps distinguish splenic lymphoma from other blood cancers and guides further management.
Treatment Strategies
Treatment for splenic lymphoma is tailored to the individual, due to its indolent nature and whether symptoms are present. For asymptomatic patients, a “watchful waiting” approach, also known as active surveillance, is adopted. This involves close monitoring of symptoms and blood counts, delaying active treatment until symptoms worsen or the disease progresses, which does not negatively impact treatment effectiveness or long-term survival.
When treatment is necessary, strategies include splenectomy, the surgical removal of the spleen, which can quickly alleviate symptoms related to an enlarged spleen and improve blood cell counts. However, splenectomy is a major surgical procedure and may not be the sole treatment, particularly for more aggressive subtypes. Targeted therapies, such as rituximab, an antibody therapy that targets CD20 protein on B-cells, are used, either alone or in combination with chemotherapy. Rituximab has shown effectiveness with minimal toxicity and can lead to significant responses. Chemotherapy may also be used, though purine analogues, while effective, can be associated with considerable toxicity. The choice of treatment depends on disease progression and the patient’s overall health.
Outlook and Monitoring
The prognosis for splenic lymphoma is favorable due to its slow-growing nature, with many individuals living for several years after diagnosis. Most cases of SMZL are indolent, though about 30% of patients may experience a more aggressive form. Rarely, SMZL can transform into a faster-growing type of lymphoma, such as diffuse large B-cell lymphoma (DLBCL).
Ongoing monitoring and follow-up care are important after diagnosis and treatment, including regular check-ups, blood tests, and potentially imaging studies to monitor for disease progression or relapse. While SMZL cannot always be cured, available treatments can effectively manage symptoms and control the disease. Long-term considerations include managing potential relapses, which are common but often responsive to further treatment, and addressing any persistent symptoms or side effects from therapies.