Table of Contents
- Introduction to Diffuse Large B-Cell Lymphoma
- Epidemiology of Diffuse Large B-Cell Lymphoma
- Etiology of Diffuse Large B-Cell Lymphoma
- Classification of Diffuse Large B-Cell Lymphoma
- Clinical Presentation of Diffuse Large B-Cell Lymphoma
- Diagnosis of Diffuse Large B-Cell Lymphoma
- Staging of Diffuse Large B-Cell Lymphoma
- Prognosis of Diffuse Large B-Cell Lymphoma
Introduction to Diffuse Large B-Cell Lymphoma
The diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin’s lymphoma (NHL). It is an aggressive, rapid-growing type of NHL that is rapidly fatal if untreated.
Epidemiology of Diffuse Large B-Cell Lymphoma
DLBCL is the most common type of NHL in the United States, accounting for 25 % to 35 % of all NHLs. The incidence rate of DLBCL is approximately 4.7 cases per 100,000 persons annually in the US, and it is constantly increasing. The incidence increases with age and the mean age at the time of diagnosis are 64 years. Men are slightly more susceptible.
Etiology of Diffuse Large B-Cell Lymphoma
The exact etiology of DLBCL has not been determined precisely yet. However, the following possible risk factors are identified for this disease:
- Infections (EBV, Kaposi sarcoma-associated human herpesvirus 8 [HHV 8], Helicobacter pylori, Chlamydia psittaci, and hepatitis C virus)
- Chronic inflammation
- Autoimmune diseases
- Environmental factors
- Long-term chemical exposure (herbicides, insecticides, and oxidative dye)
- Organ transplantation
Classification of Diffuse Large B-Cell Lymphoma
The World Health Organization (WHO) has classified DLBCL into following different sub-types depending upon specific clinical, morphologic and molecular characteristics.
- DLBCL, not otherwise specified (NOS)
- T-cell/Histiocyte-rich large B-cell lymphoma
- Primary DLBCL of the central nervous system (CNS)
- Primary cutaneous DLBCL, leg type
- Epstein-Barr virus (EBV)-positive DLBCL of the elderly
- Germinal center B-cell (GCB)-DLBCL
- Activated B-cell (ABC)-DLBCL
Clinical Presentation of Diffuse Large B-Cell Lymphoma
The clinical presentation of patients with DLBCL is very similar to other NHLs or other types of blood cancer. Most cases are accompanied by painless enlarged and swollen lymph nodes. Moreover, over 40 % of the patients have the extranodal manifestation of the disease, namely, skin, gastrointestinal tract, central nervous system, respiratory system, genitourinary tract, or the bones.
The common clinical features are as follows:
- Rapidly enlarged painless lymph nodes
- Pelvic lymphadenopathy leads to pedal edema due to the blockage of the lymph outflow
- Fever, night sweats and weight loss (so-called B-symptoms)
The cancerous cells typically target the reticuloendothelial system (lymph nodes, spleen, liver and bone marrow); hence the common physical findings are lymphadenopathy (often involving cervical, axillary and inguinal lymph nodes) and hepatosplenomegaly.
Diagnosis of Diffuse Large B-Cell Lymphoma
Histological examination: The microscopic examination of the excisional biopsy of the nodes is the gold standard for the diagnosis. It shows a diffuse spread of abnormally enlarged cells with an equal number of small and large cells, with a cleaved or indented nucleus and coarse chromatin in them.
Complete blood counts anemia, thrombocytopenia, and/or leukopenia may occur with the bone marrow involvement.
Comprehensive metabolic panel:
- Serum electrolytes
- Lactic dehydrogenase (LDH)
- Renal function
- Hepatic function
- Serum β2 microglobulin (B-cell lymphoma) testing
Bilateral iliac crest bone marrow biopsies (staging) determines the rate of bone marrow involvement.
Lumbar puncture in advanced cases (cytologic and chemical analysis of the cerebrospinal fluid).
CT scan of neck, chest, abdomen, and pelvis to know the extent of the disease and aids in the staging of DLBCL.
Positron emission tomography (PET) in higher grades of the malignant process
Bone imaging and bone marrow biopsy are needed if there is a history of unexplained bone pain, elevated alkaline phosphatase levels and/or pancytopenia.
Staging of Diffuse Large B-Cell Lymphoma
The staging of DLBCL is done, like other NHLs, by the Ann-Arbor classification.
|I||Involvement of a single lymph node region (I/N), or of a single or localized extranodal site (I/E)|
|II||Involvement of two or more lymph node regions on the same side of the diaphragm (II/N), or involvement of an extranodal site or organ (II/E) and one or more lymph node regions on the same side of the diaphragm (II/N/E)|
|III||Involvement of two or more lymph node regions on both sides of the diaphragm (III/N), or involvement of localized extranodal foci and affected lymph nodes on both sides of the diaphragm (III/E or III/N/E)|
|IV||Diffuse or disseminated involvement of one or more extralymphatic organs, with or without lymph node involvement|
Table: “DLBCL Ann Arbor staging” by biooncology.com.
Management of Diffuse Large B-Cell Lymphoma
Since DLBCL is a highly aggressive tumor and rapidly fatal if untreated, the treatment has to commence immediately. The following treatment options are available:
- Chemotherapy: The most common chemotherapy regimen for advanced DLBCL is called R-CHOP. R-CHOP includes Rituximab, Cyclophosphamide, Hydroxydaunorubicin (doxorubicin), Oncovin (vincristine) and Prednisone.
- Chemotherapy coupled with stem cell transplantation (autologous or allogeneic) in the case of relapse of the disease
- Regular check-up
Prognosis of Diffuse Large B-Cell Lymphoma
The NHL international prognostic index is used to predict the prognosis of patients with DLBCL. It consists of the following five risk factors.
- > 4 affected lymph node regions
- Lactate dehydrogenase > normal
- Age > 60 years
- Ann-Arbor stage III or IV
- Hemoglobin <12g/dl
The 5-year survival rate depends upon the presence of a number of these risk factors, which is given:
|Number of Risk Factors||Risk of Relapse||5-Year Survival Rate in %|
|0 – 1||Low||73|
|2 – 3||Intermediate||50|
|4 – 5||High||26|