[Frequency of genetic aberrations in mucosa-associated lymphoid tissue lymphoma of different sites].
OBJECTIVE
To study the frequency of certain specific genetic aberrations, including t (11; 18)/API2-MALT1, t (1; 14)/IgH-bcl-10 and t (14; 18)/IgH-MALT1, in mucosa-associated lymphoid tissue (MALT) lymphoma of different sites.


METHODS
One hundred and ninety-six cases of MALT lymphoma from Cancer Hospital of Fudan University were enrolled into the study. The samples consisted of MALT lymphomas from stomach (53 cases, including 44 cases of low-grade MALT lymphoma and 9 cases of MALT lymphoma with diffuse large B-cell lymphoma component), ocular adnexa (50 cases), salivary gland (20 cases), lung (20 cases), intestine (17 cases), skin (17 cases), liver (8 cases), thyroid (5 cases) and other sites (2 cases from tongue, 1 case from pancreas, 1 case from larynx, 1 case from vocal cords and 1 case from kidney). Fluorescence in-situ hybridization for API2-MALT1 fusion gene, bcl-10, MALT1 and IgH genes was performed on paraffin sections.


RESULTS
Among the 196 cases of MALT lymphoma, 25 cases (12.8%) possessed API2-MALT1 fusion gene. The positive rates in various sites were significantly different (P = 0.002), as follows: 45.0% (9/20) in lung, 22.7% (10/44) in stomach (without large cell component), 15.0% (3/20) in salivary gland, 2 of 17 cases in intestine and 2.0% (1/50) in ocular adnexa. The fusion gene was not detected in the 9 cases of gastric MALT lymphoma with large cell transformation. It was also negative in the MALT lymphomas from skin, thyroid and other sites. One of the pulmonary MALT lymphoma cases showed simultaneous aberrations of IgH and MALT1 genes, such as t (14; 18)/IgH-MALT1. Two of the gastric MALT lymphoma cases without large cell transformation and one of the pulmonary MALT lymphoma cases showed aberrations in both IgH and bcl-10 genes, such as t (1; 14)/IgH-bcl-10. Six cases of MALT lymphoma, including 2 cases from salivary gland, 2 cases from liver, 1 case from thyroid and 1 case from stomach (large cell transformation), showed trisomy 18. On the other hand, 3 cases, including 2 cases from stomach and 1 case from intestine, showed MALT1 gene amplification.


CONCLUSIONS
In general, specific genetic aberrations have a relatively low frequency of occurrence in MALT lymphomas. The positive rates however show a remarkable difference in tumors of different anatomic sites. This phenomenon may suggest that MALT lymphomas in different sites, though sharing similar morphologic features, may have a divergent tumorgenesis.
Li
Bai-zhou
BZ
Department of Pathology, Cancer Hospital of Fudan University, Department of Oncology, Shanghai Medical College of Fudan University, Shanghai 200032, China.
Lu
Hong-fen
HF
Zhou
Xiao-yan
XY
Yang
Wen-tao
WT
Kong
Yun-yi
YY
Fan
Yue-zhen
YZ
Shi
Da-ren
DR
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000818:Animals; D001402:B-Lymphocytes / Q000473:pathology; D002887:Chromosomes, Human, Pair 18; D005796:Genes; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D016393:Lymphoma, B-Cell / Q000235:genetics*; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics*; D009363:Neoplasm Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014178:Translocation, Genetic; D014314:Trisomy
D048868:Adaptor Proteins, Signal Transducing; D009363:Neoplasm Proteins