burkitt lymphoma

Burkitt Lymphoma

The Burkitt lymphoma is a tumor (non-Hodgkin Lymphoma) that comes from the smart evolution and proliferation of lymphoid cells of type B. It is often of viral origin. Classically, defined three variants cliniques1: the endemic form, the form associated with immunodeficiency and the sporadic form.
Other names
Different names describe the same affection2:

LAL to Burkitt cells;
LAL - B;
LAL - L3;
ALL3;
Leukemia acute lymphoblastic B;
leukemia, acute lymphoblastic of type Burkitt;
acute lymphoblastic leukemia of type Burkitt;
Burkitt leukemia;
leukemia, acute lymphocytic B;
Leukemia acute lymphocytic B;
B-cell acute Lymphocytic Leukemia;
Leukemia acute lymphocytic B-cell;
LLA - B;
disease Burkitt;
Burkitt tumor.
Causes
The Epstein-Barr virus is associated with the three forms of Burkitt Lymphoma, consistently in the endemic form of how fickle in the other two trained3. The infection precedes the development tumoral4. the mechanism of tumour transformation is unclear. Several proteins synthesized by the Epstein-Barr virus genome would be involved, resulting in alterations in the DNA of the cell contaminee5.

The promoting role of malaria was suspected in endemic form for epidemiological reasons. Some antigens of the parasite could reactivate the Epstein-Barr virus in a latent manner at a hote6.

Genetic peculiarities
Burkitt lymphoma is usually associated with a translocation of the c - myc gene (the MYC gene was also discovered for the first time in patients of Burkitt Lymphoma). This translocation is often caused by the viral oncogene EBV.

The most common locations in the genome: t (8; 14) (q24; q32) chromosome 8 region q24 to chromosome 14, region q327
Variants: the chromosome 8 to chromosome 2 or 22 t(8;2) (q24; p12); t (8; 22) (q24; q11)
Integration of the EBV genome: 100% in Africa, 30% ailleurs8
Percentage-pathology

It is the tumor the fastest with a time of between 1 and 2 days3 cell doubling.

Histologically, described this cancer as presenting an appearance of "ciel étoilé"9. The lymphoid cells particularly similar to each other, organize themselves into layers of cells with very high rates of proliferation and apoptosis.

Characteristic appearance of cells in the case of Burkitt lymphoma.
These cells have a nucleus to form round or oval, with regular outlines, chromatin, located in the central part of the core, lying reticulated with several nucleoli of ordinary size. The cytoplasm is circumscribed to the review. In immunocompromised patients, can also sometimes discover a significant differentiation of the cytoplasm with a kernel to single nucleolus.

Symptoms

We can often find either a large OSTEOLYTIC lesion of the maxilla or the mandible or an abdominal mass in rapid growth.

There is no clear clinical boundaries between the three forms, the distinction instead at the epidemiological level.

Clinical forms

The disease takes its name from Denis Parsons Burkitt (1911-1993), military surgeon who described it in 1958 in Ouganda10. He had noticed tumors of the jaw never described and yet common in children in the region. However, it will be six years later in Zaire (now DRC) that conducted the first clinical descriptions of this lymphoma. Initially took to be a Sarcoma, it is correctly classified in the lymphomas from 196011. The viral cause suspected was in 1964 by Epstein, Achong, and Barr before the presence of viral particles in the samples of lymphomes12.

It is the first discovered tumor associated with a virus and one of the first associated with a translocation chromosomique3.

Epidemiology

It is found mainly in African children with a peak of frequency between 6 and 7 years old. The most common children's tumor in Equatorial Africa, in the famous Lymphoma Belt13, it is linked to the enormous prevalence of EBV in this region. The area of prevalence of the disease covers that of the paludisme14. The disease is more common in boys than girls and regularly attacks the jaw. It can also affect the other bones in the face or abdomen but the proportions of these forms vary according to the sources15, 16 (retroperitoneal region, ovaries or mesentery).

Burkitt lymphoma is currently 2% of all syndromes lymphoproliferatifs17 (i.e., the set containing the lymphomas, leukemias, myelomas, etc) worldwide.

Form related to HIV

The AIDS epidemic has made HIV a cause of Burkitt Lymphoma to search systematically for when it is associated with an immunodeficience18, although the immunosuppressive drugs used for a transplant may also be criminalized. The form of lymphoma HIV appears clinically difficult to distinguish from the classic form.

Form sporadic or "non-africaine".

Rare disease that can be found everywhere in the world, it also affects many adults that children especially at the level of the abdomen. She seems not associated with the virus of Epstein-Barr3.

Prognostic factors

The extension (local, loco-regional or widespread) is an important prognostic factor. Some chromosomal abnormalities have a development more pejorative19.

Treatment

After the puncture of the tumor mass and stock extension (x-ray, myelogram, spinal tap), progressive and exclusive chemotherapy should be considered. It heals 80% of cases. In case of relapse or down, must be expanded (immunotherapy, radiation therapy) treatment but the prognosis dims (only 10 to 20% healing).

As with all cancers, early support is critical to decrease mortality.

Support of this Lymphoma in poor countries is much more limited.

Prevention

The fight against the virus of Epstein-Barr (EBV) and HIV is, of course, the basis of prevention. There is no vaccine available against EBV, but clinical trials are in cours20, 21. Upstream of these two pathologies prevention is seen as the key to prevention against Burkitt lymphoma.