Identifying HIV infection in diagnostic histopathology tissue samples--the role of HIV-1 p24 immunohistochemistry in identifying clinically unsuspected HIV infection: a 3-year analysis.

AIMS: Because of the clinical difficulty in identifying the early stages of human immunodeficiency virus (HIV) infection, the histopathologist often has to consider the diagnosis of HIV in tissue samples from patients with no previous suspicion of HIV infection. The aim was to investigate the practicality and utility of routine HIV-1 p24 immunohistochemistry on tissue samples received at a London histopathology laboratory. METHODS AND RESULTS: Over a 3-year period, HIV-1 p24 was evaluated immunohistochemically on 123 cases. Of these, 37 (30%) showed positive expression of p24 in lesional follicular dendritic cells (FDCs). Of these 37 cases, 11 were not clinically suspected to be HIV+ and had no prior serological evidence of HIV infection. These cases represented lymph node biopsies, tonsillar and nasopharyngeal biopsies and a parotid excision. In addition to expression on FDCs, in 22 cases (60%), p24 also highlighted mononuclear cells and macrophages. p24 was also useful in confirming the presence of HIV in lymphoid tissue in non-lymphoid organs such as the lung, anus, salivary gland and brain. Immunonegativity occurred in occasional known HIV+ cases, probably related to treatment or tissue processing. CONCLUSIONS: This study confirms the usefulness of this technique in detecting unsuspected HIV infection in lymphoid and non-lymphoid organs on histopathological material and should be part of routine evaluation of lymph nodes and lymphoid tissue in other organs if morphological or clinical features suggest HIV infection.

Hydroxyurea compared with anagrelide in high-risk essential thrombocythemia.

BACKGROUND: We conducted a randomized comparison of hydroxyurea with anagrelide in the treatment of essential thrombocythemia. METHODS: A total of 809 patients with essential thrombocythemia who were at high risk for vascular events received low-dose aspirin plus either anagrelide or hydroxyurea. The composite primary end point was the actuarial risk of arterial thrombosis (myocardial infarction, unstable angina, cerebrovascular accident, transient ischemic attack, or peripheral arterial thrombosis), venous thrombosis (deep-vein thrombosis, splanchnic-vein thrombosis, or pulmonary embolism), serious hemorrhage, or death from thrombotic or hemorrhagic causes. RESULTS: After a median follow-up of 39 months, patients in the anagrelide group were significantly more likely than those in the hydroxyurea group to have reached the primary end point (odds ratio, 1.57; 95 percent confidence interval, 1.04 to 2.37; P=0.03). As compared with hydroxyurea plus aspirin, anagrelide plus aspirin was associated with increased rates of arterial thrombosis (P=0.004), serious hemorrhage (P=0.008), and transformation to myelofibrosis (P=0.01) but with a decreased rate of venous thromboembolism (P=0.006). Patients receiving anagrelide were more likely to withdraw from their assigned treatment (P<0.001). Equivalent long-term control of the platelet count was achieved in both groups. CONCLUSIONS: Hydroxyurea plus low-dose aspirin is superior to anagrelide plus low-dose aspirin for patients with essential thrombocythemia at high risk for vascular events.