Showing papers by "D Y Mason published in 1995"

Mutations in the p53 gene are not limited to classic 'hot spots' and are not predictive of p53 protein expression in high-grade non-Hodgkin's lymphoma.

Abstract: We have investigated the relationship between the p53 genotype and phenotype in a series of 22 high-grade non-Hodgkin's lymphomas (NHLs) in which we sequenced the p53 gene open reading frame (exons 2-11). Immunostaining for p53 was already available for these cases. Mutations were found in 10/22 cases (45%) and 3/10 were in exons 4 or 10 outside the classic 'hot spot' regions (exons 5-8). Comparison with immunostaining indicated that, besides cases with the 'expected' patterns (in which gene mutation and protein detection were either both present or both absent) there were also cases in which p53 protein was detected in the absence of any mutation and those with a mutant gene in which the protein was undetectable. These data show that: (1) in high-grade NHLs mutations frequently occur outside the classic hot spot regions and (2) staining for p53 is not predictive of the status of the gene, i.e. whether or not a mutation is present. Therefore in order to document p53 involvement in lymphoid tumours it is necessary both to sequence at least the whole translated open reading frame of the gene and to show evidence of protein expression by immunostaining.

Heterogeneity of bcl-2 expression in MALT lymphoma.

Abstract: Bcl-2 protein expression was studied in a series of 58 MALT lymphomas using a monoclonal antibody which recognises this protein in routinely processed paraffin embedded tissue. Thirty-three of 58 cases showed heterogeneity for bcl-2 expression, 18 of 58 cases were bcl-2 positive and 7 of 58 were bcl-2 negative. High grade and low grade MALT lymphomas showed different patterns of staining. All 21 low grade tumours were positive for bcl-2, though in seven cases only a proportion of the neoplastic cells expressed this protein. In the 37 high grade tumours the majority of the neoplastic cells were negative with seven cases showing no reactivity at all. These findings give further support to the theory that MALT lymphomas differ in pathogenesis to nodal lymphomas and suggest that the good prognosis of MALT lymphomas may partly be explained by the fact that they maintain a normal pattern of bcl-2 expression.

Not another lymphoma classification

Abstract: Intprnational disagreeinent over non-Hodgkin ‘s lymphoma These discordant views on lymphoma classification engendered much heated debate, but today the verbal skirmishing which characterized the ‘lymphoma wars’ of the past has largely subsided, and an uneasy truce has established itself. But this is due more to exhaustion than to agreement. Most pathologists, at least in Europe, subscribe to the scheme proposed by Professor Lennert and his colleagues from Kiel (Gerard-Marchant et al, 1974; Lennert, 1978; Stansfeld et al. 1988; Lennert 81 Feller, 1992). In contrast, the majority of U.S. pathologists either use one of the schemes proposed by Kappaport and by Lukes and Collins, or support the ‘Working Formulation’, which represents an attempt in the early 1980s to establish a common international language for lymphoma pathologists and to give agreed names to entities in these conflicting schemes (NCI NonHodgkin’s Classification Project Writing Committee, 198 5) . However. given the fact that lymphoma subtypes in one