Burkitt Lymphoma

Overview

Burkitt lymphoma is a notoriously aggressive cancer of the lymphatic system. In fact, it is considered to be the fastest growing cancerous tumor among humans. Statistics show that it tends to affect more males than females and by a wide margin. The exact cause is as yet unclear but, on a genetic level, the change in expression of a certain gene on chromosome 8 has been identified as the trigger for the abnormal proliferation of B-lymphocytes which lump together to form tumors.

This type of cancer was first studied systematically among children in sub-Saharan Africa by the British surgeon after whom it is named. Further investigations into this disease led to the discovery of the Epstein-Barr virus, the first virus proven to have a definite link with cancer in humans.

Definition

Burkitt lymphoma is a cancer of the lymphatic system, primarily affecting immune cells known as B-lymphocytes and producing solid tumors in the lymphoid organs. Technically, it is referred to as a ‘Non-Hodgkin lymphoma’. It is noteworthy for the extremely high rate of proliferation of malignant cells. According to the scheme of classification endorsed by the World Health Organisation (WHO), there are three main types of Burkitt lymphoma. Of these, the most common kind is the ‘endemic’ or classic Burkitt lymphoma. This was first identified in a region of Africa where malaria was and continues to be rampant.

Two other types were identified later. The three types vary in terms of pathogenesis and symptoms as well as incidence and distribution. In general, Burkitt lymphoma can affect a number of organs and organ systems, resulting in a variety of clinical manifestations. It becomes particularly difficult to treat when it progresses into the bone marrow and central nervous system.

Causes

The abnormally rapid proliferation of B-lymphocytes, which is characteristic of Burkitt lymphoma, has been attributed to certain changes in gene expression. The oncogene in question is the Myc gene situated on chromosome 8. It is responsible for regulating cell proliferation and programmed cell death. It is unclear what causes the chromosomal translocation that interferes with the normal expression of this gene, leading to malignancy in B-lymphocytes.

Known risk factors associated with this disease are listed below:

• Compromised immunity can result in a higher risk of developing Burkitt lymphoma. This would include individuals who have a congenital immunodeficiency, a disease such as HIV/AIDS or those who have undergone organ transplantation which typically involves taking certain immunosuppressant drugs.
• There is a strong correlation between endemic Burkitt lymphoma and co-infection with  Epstein-Barr virus and the malarial parasite Plasmodium falciparum.
• In general, males are found to be at a great risk of developing Burkitt lymphoma than females.

Symptoms

The usual symptoms of Burkitt lymphoma include the presence of noticeable tumors in the jaw or other facial bones, swollen lymph nodes, abdominal tumors and the buildup of fluid in the abdominal region. The precise symptoms vary according to the different types of Burkitt lymphoma and may include the following indications:

• Loosening of the molars or premolars in children.
• Protrusion of the eyeballs.
• Enlargement of the thyroid gland.
• Sweating profusely at night.
• Loss of appetite and loss of weight.
• Symptoms resembling fever or flu.
• When the bone marrow is affected, this can lead to anemia and impairment in blood clotting.
• Diarrhea and/or bowel obstruction and/or bleeding.
• Nausea and vomiting.
• Gastrointestinal bleeding.
• Loss of renal function.
• Headaches can arise as a sign of the disease if it has spread to the central nervous system.

Types of Burkitt Lymphoma

The World Health Organisation (WHO) recognizes three main variants of the Burkitt lymphoma. These are:

• Endemic: This type is most often encountered in equatorial Africa, Papua New Guinea, and Brazil: all areas where malaria is endemic. This type usually affects children between the ages of 4 and 7 with male patients outnumbering females two to one. In Africa, the incidence of this type is linked to infection with the Epstein-Barr virus in about 98% instances. Tumors usually arise in the jaw and facial bones. Ovaries and breasts may also be affected.
• Sporadic: Constitutes 1-2% of lymphoma seen in adults and about 40% of those in children in the USA and Western Europe. It is characterized by abdominal tumors and bone marrow involvement. Ovaries, tonsils, and kidneys may also be affected.
• Immunodeficiency-related Burkitt lymphoma: This type appears to affect those who have HIV, those with congenital immunodeficiency and recipients of organ transplants. The lymph nodes and bone marrow are usually implicated.

Clinical Complications

Because this form of cancer is notorious for the speed at which it can proceed, death is possible in the absence of timely diagnosis and immediate treatment. If cancer spreads to the bone marrow or the cerebrospinal fluid, the outlook for recovery is generally poorer. The patient may experience kidney failure, loss of vision and seizures, to name a few typical complications. Paralysis and permanent disability can occur if the spinal cord is involved.

Diagnosis

The endemic form is usually clinically identifiable by soft tumor masses in the jaw and facial bones, possibly accompanied by swelling of the lymph nodes. It is important to check the patient’s medical history for evidence of immunodeficiencies, HIV or past infection with a malarial parasite or Epstein-Barr virus as these are all factors that have a direct bearing on the diagnosis.

It is especially crucial to differentiate Burkitt lymphoma from other types of high-grade B-cell lymphoma. Making this distinction is particularly complicated in adults since the incidence of Burkitt lymphoma is not as high in this group as it is among children. Hence cytological testing and immunophenotyping are indispensable in making a sound diagnosis.

Tissue biopsy of the lymph nodes or other affected sites is a necessary first step in making the diagnosis. If there is evidence of bone marrow involvement then this will also have to be tested by means of biopsy. Similarly, if there are signs of spinal involvement, a sample of cerebrospinal fluid is extracted by means of lumbar puncture. An assessment of liver and kidney function is also relevant.

Diagnostic imaging, using techniques such as X-rays, ultrasounds, magnetic resonance imaging (MRI) and computerized tomography (CT) is helpful in locating the tumors and assessing the extent of involvement of various organs, bones, and other tissues. Echocardiography is called for when the symptoms point to cardiac involvement.

Treatment and preventions

Treatments 

• Chemotherapy.
• Stem cell transplant.
• Immunotherapy.
• Targeted therapy.
• Radiation.
• Surgery (in rare cases).

Preventions – There are certain risk factors that you could avoid.

• Individuals with a weak immune system, those who have HIV/AIDS. Those who have undergone an organ transplant or are on immunosuppressant drugs.
• Limit the risk of infections and diseases.
• Maintain a diet that helps in strengthening the immune system.
• Visit the doctor regularly to monitor the symptoms in hereditary cases.

 
References