Sjögren's syndrome and MALT lymphomas of salivary glands: a DNA-cytometric and interphase-cytogenetic study.
Few and conflicting cytogenetic data are available concerning the chromosomal constitution of (mainly gastric) extranodal marginal zone B-cell non-Hodgkin's lymphoma arising from mucosa-associated lymphoid tissue (MALT)-type lymphoma. The majority of salivary gland MALT lymphomas are thought to develop from longstanding Sjögren's syndrome/benign lymphoepithelial lesion (BLEL). We tried to achieve a better comprehension of related cytogenetic alterations by comparing DNA-ploidy and numerical chromosomal (#) aberrations, assessed by different techniques of DNA cytometry (image cytometry) and interphase cytogenetics using nonradiographic in situ hybridization (centromere specific probes for #3, 7, 12, 18) on 12 cases of BLEL, 13 low-grade MALT lymphomas (LG-MALT-L) and 4 high-grade MALT lymphomas (HG-MALT-L) of salivary gland. Both techniques were applied on tissue sections preferentially, enabling a reliable measurement of histomorphologically identified areas. No case of BLEL showed cytogenetic abnormalities. Three of 4 HG- and 2 of 13 LG-MALT-L exhibited complex chromosomal gains in nonisotopic in situ hybridization, which were reflected by DNA nondiploidy in image cytometry. In 6 of 13 LG- and lof 4 HG-MALT-L, one or two numerical chromosomal aberrations were demonstrated by nonisotopic in situ hybridization, which could not be resolved by image cytometry. In the 11 DNA-diploid LG-MALT-L, trisomies 18, 3, and 12 were found in 36, 12, and 9%, respectively. In conclusion, comparing BLEL, which showed no chromosomal aberrations, with LG- and HG-MALT-L, an increase in frequency and number of numerical aberrations and DNA nondiploidy was seen. Peritetraploid DNA nondiploidy might be characteristic for HG-MALT-L of salivary gland as it is a rare finding in MALT lymphomas of other sites. It is unclear whether the documented chromosomal aberrations in LG-MALT-L, especially increased rate of trisomy 18, indicate a pathogenic impact or merely reflect genetic instability.
Ihrler
S
S
Institute of Pathology, Ludwig Maximilians University, München, Germany. Stephan.Ihrler@lrz.uni-muenchen.de
Baretton
G B
GB
Menauer
F
F
Blasenbreu-Vogt
S
S
Löhrs
U
U
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002467:Cell Nucleus / Q000235:genetics / Q000473:pathology; D002469:Cell Separation; D002869:Chromosome Aberrations; D004273:DNA, Neoplasm / Q000032:analysis*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D019044:Image Cytometry; D017403:In Situ Hybridization; D007399:Interphase; D018442:Lymphoma, B-Cell, Marginal Zone / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011003:Ploidies; D012468:Salivary Gland Neoplasms / Q000235:genetics* / Q000473:pathology; D012859:Sjogren's Syndrome / Q000235:genetics* / Q000473:pathology
D004273:DNA, Neoplasm