A 30-year-old man with a history of intravenous drug abuse and known HIV infection comes to the emergency department because of increasing abdominal distention and anorexia. A CT scan of the abdomen shows ascites and a large mass surrounding the small intestine. Biopsy of the mass reveals uniform, round, medium-sized tumor cells with basophilic cytoplasm and a proliferation fraction (Ki-67 fraction) of 99%. Which of the following infectious agents is most closely associated with the development of his current condition?

Question

A 30-year-old man with a history of intravenous drug abuse and known HIV infection comes to the emergency department because of increasing abdominal distention and anorexia.  A CT scan of the abdomen shows ascites and a large mass surrounding the small intestine.  Biopsy of the mass reveals uniform, round, medium-sized tumor cells with basophilic cytoplasm and a proliferation fraction (Ki-67 fraction) of > 99%.  Which of the following infectious agents is most closely associated with the development of his current condition?

Quizplus · Accepted Answer

11ec160b_3971_23a2_9249_79473dacde06_MD0001_00 Epstein-Barr virus (EBV) is the etiologic agent most strongly associated with Burkitt lymphoma, with infection being present in 40% of immunodeficiency-associated Burkitt lymphoma and nearly all cases of endemic Burkitt lymphoma. A crucial step in the transformation of infected cells is the balanced t(8;14) translocation, which causes overexpression of c-MYC, a transcriptional regulator that controls cell proliferation. Chronic EBV infection increases B-cell proliferation and is thought to increase the risk of a c-MYC translocation. Pre-existing immunodeficiency secondary to HIV infection can potentiate EBV antigen-induced B-cell proliferation. The histology described is classic for Burkitt lymphoma: diffuse medium-sized lymphocytes and a high proliferation index represented by the high Ki-67 fraction (approaching 100%). The classic "starry sky" appearance is usually seen, and is due to the presence of benign macrophages. (Choice B) Human papillomavirus (HPV) types 31, 33, 35, and 51 have been identified in invasive squamous cancers of the cervix, although HPV 16 and 18 are most commonly associated. The viral DNA is usually integrated into the hostcell genome. (Choice C) Although H. pylori infection may play a role in the development of gastrointestinal lymphomas, it more commonly causes chronic gastritis and peptic ulcer disease. Lymphomas associated with H. pylori infection would be expected to have a different type and histology (usually MALT lymphomas). (Choice D) Human herpesvirus 8 infection can cause Kaposi's sarcoma and primary effusion lymphoma (arising from B-cells), most commonly in HIV infected patients. The histology of primary effusion lymphoma is distinct from Burkitt lymphoma, with large cells, big nuclei, and prominent nucleoli. (Choice E) Hepatitis B infection can cause hepatocellular carcinoma. A CT scan would reveal the presence of a tumor mass or masses within the liver. Hepatocellular carcinoma, being derived from hepatocytes, is histologically and cytologically distinct from B-cell lymphomas. Educational objective: The Epstein-Barr virus genome is identified in approximately 50% of systemic B-cell lymphomas and almost all primary CNS lymphomas occurring in the setting of HIV infection. A high mitotic index is typical of Burkitt lymphoma.

A 30-Year-Old Man with a History of Intravenous Drug Abuse