Pathophysiology
1) type of B cell lymphoma 2) occurs in an “endemic” form in equatorial Africa and Papua New Guinea and a “sporadic form” in the rest of the world
Signs and Symptoms
1) sporadic – onset is usually in adolescence or early adulthood and sites affected are usually abdominal 2) endemic – onset is usually by age 7 years and sites affected are the abdomen and jaw (usually) 3) metastases occur to the CNS
Histology/Gross Pathology
1) small, noncleaved cell with round to oval nucleus 2) high mitotic rate 3) “starry sky” pattern
Associated Conditions
1) endemic – strongly associated with infection with EBV 2) 1,000 times increased incidence in HIV 3) tumor lysis syndrome and related hyperuricemia, lactic acidosis, hyperkalemia, and renal injury
Biochemistry
1) EBV-stimulated B cell proliferation is shut down by T suppressor cells 2) endemic – T suppressor cells are impaired by malaria infection
Inheritance/Epidemiology
1) associated with three gene translocations – 8/14, 8/2, and 8/22 2) the effect of these translocations is to put the c-myc oncogene physically next to genes that control transcription of immunoglobulin heavy or light chains 3) parts of Africa – 90% of cases are associated with Ebstein Barr virus 4) Japan – 90% of cases are associated with HTLV-1 5) USA – 10% of cases are associated with EBV 6) 90% of sporadic cases occur in men 7) median age of sporadic cases is 31 years 8) considered the most rapidly progressive of all lymphoid malignancies
Treatment
1) cyclophosphamide-based combination chemotherapy 2) prophylactic therapy to CNS 3) cure rates of 70% if prompt initiation of chemotherapy
Tips for USMLE
four key steps in endemic cases are – 1) EBV infection 2) T suppressor cells shut down by malaria infection 3) c-myc gets next to immunoglobulin gene through translocation (8/14, 8/2, or 8/22 and turns it on) 4) B cells proliferate wildly
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