Burkitt’s Lymphoma Catherine Hanson Richard Hildreth David Duke Kelly Lewis Ray Lewis

- Burkitt’s Lymphoma – Background * Burkitt's lymphoma (BL) is a tumor which was first described in 1958 by Denis Burkitt, a surgeon working in Africa. It is a solid tumor of B Lymphocytes which form part of the white cell population in the blood and lymph glands. It is one form of non-Hodgkin's lymphoma. The type of cell affected in Burkitt's lymphoma is the B lymphocyte which is normally involved in fighting infection by producing antibodies.

- Burkitt’s Lymphoma - Karyotype: * Here is an actual karyotype (courtesy of Janet Finan and C. M. Croce) of a cell from the tumor of a patient with Burkitt's lymphoma. The long (q) arm of the resulting chromosome 8 is shorter (8q-) than its normal homologue; the long arm of translocated chromosome 14 longer (14q+).

- Burkitt’s Lymphoma - Incidence The incidence of Burkitt's lymphoma shows great geographical variation. It is the most common childhood tumor in equatorial Africa but is very rare in children in Western countries. Recently Burkitt's lymphoma has been diagnosed in around 2% of AIDS patients. Males are three times more likely to suffer from othis disorder as opposed to females. Burkitt’s is a rare form of cancer and there are only about 100 new cases each year in the United States.

- Burkitt’s Lymphoma - * In most (approximately 90%) of the cases of Burkitt's lymphoma, a reciprocal translocation has moved the proto-oncogene c-myc from its normal position on chromosome 8 to a location close to the enhancers of the antibody heavy chain genes on chromosome 14.

- Burkitt’s Lymphoma - Causes * In almost all cases of African Burkitt's lymphoma the cells carry a virus known as Epstein-Barr virus (EBV) named after the two British scientists who discovered it. * This virus is very common and over 90% of adults throughout the world have evidence of past infection. Clearly not everyone develops the tumour and so EBV alone oes not cause Burkitt's lymphoma. It must be only one of the factors necessary for the disease to develop. * Oher possible con-tributory factors are chronic malaria infection in Africa and infection with the AIDS virus (human immunodeficiency virus - HIV) in Western countries.

- Burkitt’s Lymphoma – Signs & Symptoms * Effects depend on the site of the tumor in the body: * In African Burkitt's lymphoma the jaw is the commonest site where it causes visible swelling of the cheek and loosening of the teeth. * In non-African Burkitt’s lymphoma the tumor commonly arises in the abdomen where it causes swelling and discomfort. This picture shows the tumor cells of a Burkitt’s Lymphoma patient. Like all malignant tumors, Burkitt's lymphoma is very rapidly growing and often arises in, or spreads to, multiple sites.

-Burkitt’s Lymphoma – Diagnosis * Burkitt's lymphoma is diagnosed from a biopsy sample of the tumor. A small piece of the tumor is removed by surgery and the sample, stained by specific dyes, is examined under the microscope by a pathologist. * Burkitt's lymphoma can be differentiated from other tumors by the distinctive pattern of tumor cells which is known as a starry-sky pattern. It is possible to use specialized laboratory techniques to determine the presence of EBV in the tumor cells.

-Burkitt’s Lymphoma – Diagnosis … cont’d * Biopsies of Burkitt’s Lymphoma patients show a ‘starry sky’ pattern like the one seen to the left.

-Burkitt’s Lymphoma – Treatment * Although Burkitt's lymphoma is a very rapidly growing tumor it responds well to treatment. In African children the drug cyclophosphamide is the treatment of choice. This drug is so effective that one dose may be enough to cause the tumor to disappear. However, it is very important to complete the course of treatment in order to prevent the tumor recurring. * In AIDS patients treatment is less successful because of the underlying HIV infection. In addition to drugs, these patients are usually given X-rays which cause the tumor to shrink.