B cell infection with EBV is latent, and the virus does not undergo replication. These latently infected B cells can then go on to produce proteins that function to promote cellular growth through modification of normal signaling pathways. EBV promotes the development of malignant B cells via proteins that limit apoptosis in cells that had the c-myc translocation. Apoptosis is limited by EBV through various means such as the EBNA-1 protein, BHF1 protein, EBER transcripts, vIL-10 gene, BZLF1, and LMP1. Malaria has been found to cause genomic instability in endemic Burkitt lymphoma. Malaria can lead to the reactivation of latent EBV and also MYC translocations via activation of the toll-like receptor 9. Malaria also promotes B-cell proliferation by altering the regular immune response. The immune system targets antigens (e.g., EBNA2 and LMP-1) and eliminates most B cells infected with EBV. Downregulation of antigens targeted by the immune system leads to the development of persistent B cells. These B cells can then undergo further mutations (e.g., c-myc translocation) that promote cancer development. Immunology
Burkitt Lymphoma cells express HLA class I molecules normally, as well as some HLA class II complexes; however, CD4+ T cells are not properly activated. Burkitt lymphoma cells only express EBNA 1, a poorly antigenic EBV-associated antigen, that is able to escape HLA class I presentation, thus evades an immune response. EBNA 1 can be presented via HLA class II molecules, however HLA Class II pathway is unable to activate the CD4+ T cells.
Stewart–Treves syndrome refers to a lymphangiosarcoma, a rare disorder marked by the presence of an angiosarcoma (a malignant tumor of blood or lymph vessels) in a person with chronic (long-term) lymphedema. Although it most commonly refers to malignancies associated with chronic lymphedema resulting from mastectomy and/or radiotherapy for breast cancer, it may also describe lymphangiosarcomas that result from congenital and other causes of chronic secondary lymphedema. Lymphangiosarcoma arising from cancer-related lymphedema has become much less common with better surgical techniques, radiation therapy, and conservative treatment. The prognosis, even with wide surgical excision and subsequent radiotherapy, is poor. Cause
Common risk factors that may lead to the development of lymphangiosarcoma include lymphatic blockage, radiotherapy, mastectomy, cardiovascular diseases, and hypertension. The sarcoma first appears as a bruise mark, a purplish discoloration or a tender skin nodule in the extremity, typically on the anterior surface. Lymphangiosarcoma is caused by chronic lymphedema. Causes of lymphedema include:
Primary lymphedema
Congenital
Precox (adolescence)
Tarda (adulthood)
Secondary lymphedema
Malignancy
Recurrent cellulitis
Connective tissue disease
Infection (filariasis)
Contact dermatitis
Lymphatic damage (surgery, radiation therapy, burns, etc.). Treatment
The treatment of choice is a large resection or amputation of the affected limb. Radiation therapy can precede or follow surgical treatment. Tumors that have advanced locally or have metastasized can be treated with mono or polychemotherapy, systemically or locally. However, chemotherapy and radiation therapy have not been shown to improve survivorship significantly. In cases of upper limbs, forequarter amputation (disarticulation of upperlimb along with clavicle and scapula) is preferred. Prognosis
Early detection is key.