Burkitt lymphoma cells represent a highly aggressive form of cancer that originates from B-lymphocytes, a type of white blood cell involved in the immune system. This particular lymphoma is known for its rapid progression and can affect various parts of the body, including the jaw, abdomen, and central nervous system. Early identification and treatment are important for improving outcomes.
Unique Features of Burkitt Lymphoma Cells
Burkitt lymphoma cells have distinct morphological and behavioral characteristics. These cells exhibit an exceptionally rapid proliferation rate, making Burkitt lymphoma one of the fastest-growing human malignancies, with a doubling time of around 25 hours. Under a microscope, they generally appear as uniform, medium-sized lymphocytes with round to oval nuclei containing two to five nucleoli and basophilic cytoplasm, which often contains lipid vacuoles.
A hallmark microscopic feature of Burkitt lymphoma is the “starry sky” appearance. This pattern results from scattered “tingible body macrophages” that engulf debris from numerous dying tumor cells. The rapid division of Burkitt lymphoma cells causes high cell death, and these macrophages clear the remnants, creating pale, clear spaces against the dark blue background of densely packed tumor cells. This high mitotic activity often nears 100% Ki67 positivity.
The Role of MYC Gene Translocation
The central molecular event driving Burkitt lymphoma is a chromosomal translocation involving the MYC gene. The MYC gene normally functions as a transcription factor, playing a role in regulating various cellular processes, including cell growth, proliferation, and programmed cell death. In Burkitt lymphoma, a chromosomal translocation occurs, meaning a piece of one chromosome breaks off and attaches to another.
The most common translocation is t(8;14), occurring in 75-85% of cases, where the MYC gene from chromosome 8 is moved next to the highly active immunoglobulin heavy chain (IGH) gene enhancers on chromosome 14. Less common variants include t(2;8) and t(8;22), where MYC is translocated to immunoglobulin light chain loci (kappa on chromosome 2 or lambda on chromosome 22). These rearrangements lead to uncontrolled and continuous expression of the MYC gene, which then drives the characteristic rapid and aggressive growth of Burkitt lymphoma cells.
Factors Influencing Their Development
Several factors influence the development of Burkitt lymphoma cells, notably the Epstein-Barr Virus (EBV). In endemic Burkitt lymphoma, prevalent in equatorial Africa, EBV is found in nearly 100% of cases. EBV can contribute to B-cell proliferation, and in individuals with weakened immune systems, EBV-infected B-cells can proliferate excessively.
Chronic immune suppression, such as that seen in patients with HIV/AIDS, also plays a role in the development of immunodeficiency-associated Burkitt lymphoma. In these cases, impaired immune surveillance allows EBV-infected B-cells to escape control and acquire the MYC translocation. Co-factors like chronic malaria, particularly Plasmodium falciparum, further weaken the immune response to EBV, leading to increased viral loads and promoting the B-cell proliferation necessary for the MYC translocation to occur.
Identifying Burkitt Lymphoma Cells
Identifying Burkitt lymphoma cells involves tissue biopsy and specialized laboratory tests. A tissue biopsy, often from a tumor mass or bone marrow, is obtained for examination. Microscopic examination of these biopsies typically reveals the characteristic “starry sky” pattern, along with the uniform morphology of medium-sized, rapidly dividing cells.
Beyond morphology, specific laboratory tests are used for definitive diagnosis. Immunohistochemistry (IHC) is employed to detect specific protein markers on the cell surface and within the cells. Burkitt lymphoma cells typically express B-cell markers such as CD19, CD20, CD10, and BCL6, while being negative for BCL2. A Ki-67 proliferation index close to 100% is also characteristic. To confirm the presence of the MYC gene translocation, techniques like Fluorescence In Situ Hybridization (FISH) or Polymerase Chain Reaction (PCR) are performed, detecting specific genetic rearrangements involving chromosome 8 and immunoglobulin loci.