The most important well-known risk factor for developing B-cell neoplasias is defects of the immune system either by immunosuppression or autoimmunity. Immunosuppression from HIV is an important risk factor with a significant increase in incidence of non-Hodgkin lymphoma of this patient group. Post-transplantation proliferative conditions (often B-cell lymphomas) occur in organ transplant patients using immune-suppressing medications to prevent grafter-versus-host disease and rejection of transplantation. In such cases, reduced immune status with EBV is important for pathogenesis.
Infectious diseases have been known to cause development of different forms of B-cell lymphoma. The most classic example is the association between Epstein-Barr virus (EBV) and endemic Burkitt's lymphoma in Africa. There are also indications that the human herpes virus 8 plays an important role in primary effusion lymphoma and HIV infection with multicentric Castleman's disease. Hepatitis C may be associated with multiple forms of lymphoma.
SV40 virus (ape virus) specific sequences are observed in 40% of non-Hodgkin lymphoma. It is speculated that this is introduced through SV40 contamination of the polio vaccine. The most definitive example that bacteria can represent a cause is MALT lymphoma in the stomach where eradication of Helicobacter pylori may cause tumor regression.
There is a higher frequency of non-Hodgkin lymphoma among patients with rheumatoid arthritis. It is likely that both chronic B-cell activation as part of autoimmunity and use of immunosuppressive medications play roles. It is also reported that non-Hodgkin lymphoma is associated with Sjøgrens syndrome and Hashimoto's thyroiditis.
There is also a slight increase in frequency of B-cell lymphomas in persons exposed to solvents, dyes, and pesticides over time.
Despite accumulation of malignant lymphomas in families, a positive genetic disposition has not been confirmed.
Overview of B-cell lymphomas
- B-lymphoblastic leukemia/lymphoma
Mature B-cell neoplasias - indolent non-Hodgkin B-cell lymphomas
- Small cell lymphocytic lymphoma (SLL)/chronic lymphatic leukemia (KLL)
- Waldenstrøm's macroglobulinemia – lymphoplasmocytic lymphoma
- Solitary plasmocytoma in bone, extraosseous plasmacytoma
- Extranodal marginal zone B-cell lymphoma (MALT lymphom)
- Splenic marginal zone B-cell lymphoma
- Nodal marginal zone B-cell lymphoma
- Follicular lymphoma grade 1 and 2 and 3A
This group of lymphomas is slow-growing and constitutes about 40% of all non-Hodgkins lymphomas. The indolent non-Hodgkins lymphomas, previously called low-grade lymphomas, can today not be cured if the disease is advanced. If the disease is confined, radiation therapy can be given locally, which can cure the disease. Most patients, however, have advanced disease when diagnosed.
Expected survival does not change whether treatment starts early or late in the disease course. Normally, treatment begins when the patient needs treatment for bothersome symptoms from the disease. Factors that determine the need for treatment are general health symptoms, secondary autoimmune conditions, threating organ complications, bone marrow failure, and progressing/symptom-causing nodal tumor. If the patient does not have bothersome symptoms from the disease, the best option is "wait and see", where the patient is left untreated until bothersome consequences of the disease appear. Some patients find it difficult to leave the hospital with a lymphoma diagnosis and not receive treatment. It is therefore important to provide adequate information to the patient.
Aggressive non-Hodgkin B-cell lymphomas
- Mantle cell lymphomas
- Follicular lymphomas grade 3B
- Diffuse large cell B-cell lymphomas (DLBCL) including mediastinal (thymic)
- Large cell B-cell lymphoma
- Burkitt's lymphoma
- Other variants
B-celle proliferations with uncertain malignancy potential
- Lymphatoid granulomatosis
- Polymorphic post-transplantation lymphoproliferative disease