Which of the following conditions is associated with overexpression of bcl-2?
Correct Answer: Follicular lymphoma
Description: bcl-2 inhibits apoptosis; a (14;18) translocation resulting in overexpression of the bcl-2 protein in B lymphocytes causes apoptosis of neoplastic cells to be permanently inhibited, producing follicular lymphoma. Follicular lymphoma involves the lymph nodes and bone marrow of older people and is characterized by slow, but relentless, growth. Thus, this lymphoma allows a long survival even without any treatment. Indeed, follicular lymphoma is resistant to aggressive therapy because of its low mitotic activity. Acute lymphoblastic leukemia (ALL) is a neoplasm of pre-B cells that affects children. Different molecular mechanisms probably account for different cases. Hyperdiploidy, the Philadelphia chromosome, t(12;21), and t(4;11) are variably found in patients with ALL. Burkitt lymphoma occurs in different clinical settings, including the African endemic, sporadic non endemic, and AIDS-associated forms. Histologically, all these forms are identical and are derived from neoplastic transformation of B cells expressing surface IgM. Common to all forms are translocations involving the c-myc oncogene (chromosome 8) and Ig loci (chromosome 14). These translocations lead to overexpression of c-myc, which encodes a nuclear transcription protein, resulting in sustained cell replication. The African form is associated with Epstein-Barr virus infection. Multiple myeloma is a neoplasm of terminally differentiated B lymphocytes that secrete large amounts of monoclonal Ig or its fragments (light or heavy chains). Approximately 25% of cases have translocations that lead to overexpression of FGFR3, a receptor for fibroblast growth factor implicated in control of cell proliferation.
Category:
Pathology
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