First insights into the molecular basis of pleomorphic adenomas of the salivary glands.
Pleomorphic adenoma, or mixed tumor of the salivary glands, is a benign tumor originating from the major and minor salivary glands. Eighty-five percent of these tumors are found in the parotid gland, 10% in the minor (sublingual) salivary glands, and 5% in the submandibular gland. It is the most common type of salivary gland tumor, accounting for almost 50% of all neoplasms in these organs. In fact, after the first observation of recurrent loss of chromosome 22 in meningioma, this was the second type of benign tumor for which non-random chromosomal changes were reported. The rate of malignant change with the potential to metastasize has been reported to be only 2 to 3%, and only a few cases of metastasizing pleomorphic salivary gland adenomas have been described to date. The fact that these tumors arise in organs located in an ontogenetic transitional zone, a region where endoderm and ectoderm meet, might be one of the reasons for the often-problematic histopathological classification. This type of benign tumor has been cytogenetically very well-characterized, with several hundreds of tumors karyotyped. In addition to the cytogenetic subgroup with an apparently normal diploid stemline (making up approximately 30% of the cases), three major cytogenetic subgroups can be distinguished. In addition to a subgroup showing non-recurrent clonal abnormalities, another subgroup is various translocations involving 12q15. By far the largest cytogenetic subgroup, however, consists of tumors with chromosome 8 abnormalities, mainly showing translocations involving region 8q12. The most frequently encountered aberration in this group is a t(3;8)(p21;q12).
Voz
M L
ML
Laboratory for Molecular Oncology, Center for Human Genetics, University of Leuven & Flanders Interuniversity Institute for Biotechnology, Belgium. marianne.voz@med.kuleuven.ac.be
Van de Ven
W J
WJ
Kas
K
K
D008949:Adenoma, Pleomorphic / Q000235:genetics* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D002869:Chromosome Aberrations; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004171:Diploidy; D004475:Ectoderm / Q000473:pathology; D004707:Endoderm / Q000473:pathology; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D007621:Karyotyping; D012468:Salivary Gland Neoplasms / Q000235:genetics* / Q000473:pathology; D014178:Translocation, Genetic; D016335:Zinc Fingers / Q000235:genetics
D004268:DNA-Binding Proteins; C104382:PLAG1 protein, human