M-FISH in gastric lymphoma.

The majority of gastric B-cell lymphomas histologically are classified as low grade mucosa-associated lymphoid tissue (MALT lymphoma) and diffuse large B-cell lymphomas (DLBCL). There is evidence that the different histologic types are genetically heterogeneous, evolving through different pathogenetic pathways. Recurrent cytogenetic aberrations have been found in MALT lymphoma, whereas in DLBCL, limited cytogenetic data are available. We report here a DLBCL and a Burkitt-like gastric lymphoma case, cytogenetically studied by G-banding and M-FISH technique. In the first case, gains of chromosome 3, 7, 13, and 18 were found. An additional ring chromosome 1 identified as a clonal abnormality suggested clonal evolution. In the second case, trisomy 8, del(6)(q13), as well as t(8;14), t(1;5), and t(1;7), were observed. To our knowledge, cytogenetic data for gastric Burkitt-like lymphoma have not been reported, and M-FISH has not previously been used in the study of gastric lymphomas.

Detection of genetic alterations in primary bladder carcinoma with dual-color and multiplex fluorescence in situ hybridization.

Cytogenetic studies of bladder cancer have shown several nonrandom aberrations. Numerical aberrations of both sex chromosomes were investigated in 32 primary bladder tumors with bicolor fluorescence in situ hybridization (FISH). Loss of chromosome Y and overrepresentation of chromosome X were observed in subgroups of male patients. Chromosome X was represented normally in female patients. Two of the above primary bladder tumors, a transitional cell carcinoma (TCC) and an adenocarcinoma, were further analyzed with both multiplex FISH (24-color M-FISH) and G-banding. Both cases exhibited 1) common breakpoints on 5q11 approximately q12 and 15q24; 2) involvement of the pericentromeric area of chromosome 13; 3) structural abnormalities of chromosomes 8 and 17, with loss of material on the short arm; 4) structural abnormalities involving chromosome 11; and 5) loss of chromosome Y. The TCC case also exhibited structural abnormalities of chromosome 9, resulting in loss of 9q. The combined G-banding and M-FISH findings could help reveal regions potentially involved in bladder tumorigenesis.

Application of multiplex fluorescence in situ hybridization in the cytogenetic analysis of primary gastric carcinoma.

The different genetic alterations observed in diffuse and intestinal types of gastric cancer suggest that these two pathological types may represent different disease entities. We present two cases of primary gastric carcinoma, a well-differentiated intestinal type adenocarcinoma and a poorly differentiated diffuse type adenocarcinoma, both studied by a 24-color multiplex fluorescence in situ hybridization technique (M-FISH). The well-differentiated intestinal type adenocarcinoma exhibited fewer structural abnormalities with five noncomplex translocations, deletions of chromosomes 5q, 6q, and 17q and an i(8q). In the case of poorly differentiated diffuse carcinoma, structural abnormalities predominated and normal homologues were mostly absent. But there were also similarities between the two cases: translocations on 1p and 9p; structural abnormalities of chromosome 8 with consistent loss of 8p; structural abnormalities of 12q; partial loss of chromosome 17 and 18; and polysomy of chromosome 20. This study shows that M-FISH is valuable in identifying hidden structural abnormalities and could, therefore, be useful in the investigation of primary solid tumors.