We identified eight cases of T-cell lymphoma with evidence of a gamma delta phenotype over a 13-year period. Seven of these cases conformed to a distinct clinicopathologic entity of hepatosplenic gamma delta T- cell lymphoma. Nearly all of these patients were young adult males (five of seven), with a median age at presentation of 20 years. They presented with marked hepatosplenomegaly, without lymphadenopathy or significant peripheral blood lymphocytosis. Thrombocytopenia was seen in all patients, and five of seven were mildly anemic. The clinical course was aggressive, and despite multiagent chemotherapy, the median survival duration was less than 1 year. The morphologic findings were uniform; a monomorphic population of medium-sized lymphoid cells with moderately clumped chromatin and a rim of pale cytoplasm infiltrated the sinusoids of the spleen, liver, and bone marrow. The cells had a characteristic immunophenotype: CD2+, CD3+, CD4-, CD5-, CD7+, CD16+, CD57-, CD25-, T-cell receptor (TCR)delta +, beta F1-. CD8 was positive in four of seven cases tested, and CD56 was positive in five of six. All cases expressed the cytotoxic granule-associated protein, TIA1, but perforin was detected in only one case. All cases with assessable DNA had a TCR gamma gene rearrangement, and lacked Epstein-Barr virus sequences. Isochromosome 7q was identified in two cases with cytogenetic information. The one case of cutaneous gamma delta T-cell lymphoma differed in its clinical manifestations, histologic appearance, and immunophenotype. We conclude that hepatosplenic gamma delta T-cell lymphoma is a distinct clinicopathologic entity derived from cytotoxic gamma delta T cells, and should be distinguished from other lymphomas of T-cell and natural-killer cell (NK)-like T-cell derivation.
A773and may differ in surgical site infection (SSI) risk. This study aims to explore the use of value of information methods to assess if a new RCT is a cost-effective use of resources, to compare the value of different study designs, and compare results with standard sample size calculations. Methods: We develop a simple decision tree model to compare the costs and quality of life resulting from different wound dressing types, which may differ in SSI risk. We use results from a network metaanalysis to inform the relative efficacy of the different dressing types. Expected Value of Sample Information (EVSI) is computed to evaluate the value of reducing uncertainty by running an RCT for various included interventions and sample size. Population EVSI is presented for 1.208m wounds over a 5-year time horizon. We compare the results with those from standard sample size calculations. Results: There was considerable uncertainty as to which dressing type is the most costeffective. Population EVSI indicates that an RCT comparing dressings is likely to be of value and that designs that compare Simple Dressings vs Glue have much higher value than designs that do not make this comparison. Balanced designs comparing Simple Dressings vs Glue vs Exposed have population EVSI of £1515m, £2057m, and £2150m for total sample sizes of 500, 2500, 5000 resp. Standard sample size calculations suggest a much larger sample (around 25000). ConClusions: We discuss possible reasons for obtaining a smaller sample size with the value of information approach compared to standard sample size calculations and implications for trial design.
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