{"paper_id":"0734b03e-8202-4e17-bb0f-f2a0819e37a2","body_text":"Higher frequency of chromosomal aberrations\nin ovarian endometriosis compared to\nextragonadal endometriosis: a possible\nlink to endometrioid adenocarcinoma\nMeike Ko¨ rner1, Elisabeth Burckhardt 1 and Luca Mazzucchelli 2\n1Institute of Pathology, University of Bern, Bern, Switzerland and 2Istituto Cantonale di Patologia, Locarno,\nSwitzerland\nEndometriosis may progress to invasive endometrioid adenocarcinoma, particularly in the ovary. Up to now,\nlittle is known of the molecular mechanisms possibly involved in the malignant transformation of\nendometriosis. Therefore, in this study, extragonadal endometriosis ( n ¼ 10), ovarian endometriosis without\nmalignancy (n ¼ 10), ovarian endometriosis with direct transition into endometrioid adenocarcinoma ( n ¼ 8), and\nnormal endometrium ( n ¼ 12) were investigated for numerical chromosomal aberrations by fluorescence in situ\nhybridization using centromere enumeration probes. The proportions of cells with aneusomies were\nsemiquantitatively assessed. Trisomies 1 and 7, and monosomies 9 and 17 were found in endometriosis,\novarian endometrioid adenocarcinoma, and normal endometrium. The proportions of aneusomic cells were\nsignificantly higher in ovarian endometrioid carcinoma compared with ovarian endometriosis ( Po0.001), and in\novarian endometriosis compared with extragonadal endometriosis and normal endometrium ( Po0.001). The\ndata provide new evidence of a common lineage of endometriosis and ovarian endometrioid carcinoma. The\nhigher frequency of chromosomal aberrations in endometrioid carcinoma than in endometriosis may reflect an\nexpansion of aberrant cell clones already present in endometriosis during the progression to cancer. The\nhigher frequency of chromosomal aberrations in ovarian endometriosis than in extragonadal endometriosis\nsuggests a role of the ovarian stromal milieu in the induction of genetic changes, which may eventually lead to\ninvasive cancer.\nModern Pathology (2006) 19, 1615–1623. doi:10.1038/modpathol.3800699; published online 15 September 2006\nKeywords: endometriosis; endometriod adenocarcinoma; ovary; FISH\nEndometriosis is associated with endometrioid\nadenocarcinoma, particularly in the ovary and more\nrarely at extragonadal sites. 1,2 Several epidemiologi-\ncal and morphological observations suggest that\nendometriosis is indeed a precursor of ovarian\nendometrioid carcinoma. Endometriosis and ovar-\nian carcinoma share many risk factors, 2 and en-\ndometriosis is significantly more common in\npatients with ovarian endometrioid carcinoma than\nin patients with ovarian serous or mucinous carci-\nnoma.3 Furthermore, in early stage ovarian endome-\ntrioid carcinoma, a direct transition from benign\nendometriosis to carcinoma can be observed micro-\nscopically.4 However, so far there is only little data\nlinking endometriosis and cancer at the molecular\nlevel. For instance, one study showed that synchro-\nnous endometriosis and carcinoma share many loss\nof heterozygosity (LOH) events when present in the\nsame ovary, but not when occurring in contralateral\novaries.5\nRecently, multiple numerical chromosomal aber-\nrations were found in benign ovarian structures,\nnamely in the ovarian surface epithelium and in\ncortical inclusion cysts. 6 The same aneusomies were\nalso found, at a higher frequency, in ovarian serous\ntumors, providing a link at the molecular level\nbetween the ovarian surface epithelium and cortical\ninclusion cysts on the one hand and ovarian serous\ncancer on the other. In addition, aneusomies were\nfound to be more frequent in inclusion cysts than in\nthe surface epithelium, suggesting a role of the\nspecialized ovarian stromal milieu, to which inclu-\nsion cysts are more exposed than the surface\nepithelium, in the development of genomic\nchanges.7 In analogy, it can be hypothesized that\nendometriosis as a putative precursor of ovarian\nReceived 6 June 2006; revised 8 July 2006; accepted 21 August\n2006; published online 15 September 2006\nCorrespondence: Dr M Ko ¨ rner, MD, Institute of Pathology,\nUniversity of Bern, Murtenstrasse 31, 3010 Bern, Switzerland.\nE-mail: meike.koerner@pathology.unibe.ch\nModern Pathology (2006) 19, 1615–1623\n& 2006 USCAP , Inc All rights reserved 0893-3952/06 $30.00\nwww.modernpathology .org\n\ncancer may harbor chromosomal aberrations asso-\nciated with malignancy. 8,9 Indeed, several chromo-\nsomal aberrations, in particular monosomy 17, have\nbeen described in endometriosis. 10–12 However,\nwhether these aberrations are associated with\nmalignant transformation remains unknown.\nFurthermore, it is unclear whether chromosomal\naberrations in endometriosis occur mainly in the\novary, or if they can also be found in endometriosis\noutside the ovary.\nThe aims of the present study were: first, to\nanalyze a subset of numerical chromosomal aberra-\ntions in endometriosis; second, to investigate\nwhether the identified chromosomal aberrations\nprovide evidence of a link between endometriosis\nand ovarian endometrioid adenocarcinoma; and,\nfinally, to look for differences, with respect to\nchromosomal aberrations, between ovarian endome-\ntriosis and extragonadal endometriosis that might\nresult from putative interactions with the specia-\nlized ovarian environment. As to technical ap-\nproach, we opted for fluorescence in situ\nhybridization (FISH) since this method allows a\ngood correlation of the results with morphology and\noffers several advantages in the evaluation of\ngenomic changes in small precursor lesions over\nother techniques, such as conventional cytogenetic\nanalysis, comparative genomic hybridization, or\nLOH analysis. 6,13\nMaterials and methods\nTissue Samples\nFormalin-fixed, paraffin-embedded tissue samples\nwere obtained from surgical resection specimens.\nThe following cases were analyzed: extragonadal\nendometriosis in the peritoneum, bladder wall,\nappendix, colon, and abdominal wall ( n ¼ 10);\novarian endometriosis occurring in the absence of\nany malignancy ( n ¼ 10); ovarian endometriotic\ncysts in direct continuity with primary ovarian\nendometrioid adenocarcinoma, meeting Sampson’s\nand Scott’s criteria for carcinoma arising in endo-\nmetriosis14,15 (n ¼ 8); and normal endometrium from\nwomen in the reproductive phase and in the\npostmenopause (n ¼ 12). Of note, in the investigated\nendometriosis samples, neither hyperplasia nor\ncytological atypia was present.\nThe study conformed to the ethical guidelines of\nthe Institute of Pathology, University of Bern,\nSwitzerland, and of the Istituto Cantonale di\nPatologia, Locarno, Switzerland, and was reviewed\nby the respective Institutional Review Boards.\nFISH Studies\nBased on haematoxylin and eosin (H&E)-stainings,\nwe selected representative tissue sections of endo-\nmetriosis, endometrioid carcinoma, and normal\nendometrium. Adjacent serial tissue sections were\nhybridized with combinations of two differentially\nlabeled centromere probes for chromosomes 1, 7, 9,\nand 17 (Vysis Inc., Downer’s Grove, IL, USA). The\ncentromere probes were selected according to\nnumerical aberrations found in ovarian endome-\ntrioid carcinoma in previous studies 16–19 and in own\npreliminary investigations. Standard chromosome\npreparations of peripheral blood lymphocytes were\nused as controls for probe specificities in each\nhybridization procedure. The procedure was carried\nout as described previously 20 and indicated by the\nmanufacturer. Four-micrometer-thick tissue sections\nwere dewaxed, pretreated, and then denatured at\n731C in a 70% formamide/2 /C2SSC solution for\n5 min. After dehydration and treatment with protei-\nnase K, the tissue was exposed to the hybridization\nmixture overnight at 37 1C. The slides were then\nwashed and counterstained with DAPI II (125 ng/ml;\nVysis Inc.) in an antifade solution. The signals were\nevaluated by one experienced investigator (EB)\naccording to established criteria. 21 To avoid mis-\ninterpretations, only cells with at least one bright\nsignal were evaluated. T wo signals were counted as\none if they lay very close ( r0.5 mm) to each other. In\neach case, at least 100 cells in endometriosis and/or\ncarcinoma or endometrium were counted, and the\npercentages of nuclei with one, two, or three signals\nwere recorded. Endometrial epithelial cells and\nendometrial stromal cells were evaluated separately\nin endometriosis and in the endometrium.\nIn each case, normal control tissues were evalu-\nated. These included cortical stromal cells in the\novary, connective tissue cells adjacent to extraovar-\nian endometriosis, and myometrial smooth muscle\ncells adjacent to the endometrium. For all probes,\nthe average numbers of nuclei with one, two, and\nthree signals did not differ significantly between\nthese control tissues, providing evidence of the\nconsistency of the procedures. The control tissues\nserved as reference for the determination of the\nsignificance of chromosomal gains and losses in the\ninvestigated tissues.\nStatistics\nA statistical analysis was performed to evaluate\nwhether the percentages of nuclei with one or three\nsignals differed significantly between control tis-\nsues, extragonadal endometriosis, ovarian endome-\ntriosis, ovarian carcinoma, and normal\nendometrium. For this purpose, the Student’s t-test\nwas used; Po0.05 was considered to be statistically\nsignificant. To confirm the results of the Student’s t-\ntest, it was also calculated whether the differences\nin the mean percentages of nuclei with one or three\nsignals between the investigated groups exceeded\ntwo standard deviations from the mean; this was\nalways the case when the Student’s t-test yielded\nPo0.05.\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1616\nModern Pathology (2006) 19, 1615–1623\n\nResults\nTrisomies 1 and 7 and monosomies 9 and 17 were\nfound in extragonadal endometriosis, ovarian en-\ndometriosis, ovarian endometrioid adenocarcinoma,\nand normal endometrium: these tissues harbored\nsignificantly more nuclei with three signals for\nchromosomes 1 and 7 and one signal for chromo-\nsomes 9 and 17 in epithelial cells (Table 1) and\nstromal cells (Table 2) than the control tissues\n(Table 3) ( Po0.001).\nThe chromosomal aberrations in the epithelial\ncells are shown in Figure 1, exemplified by an\nendometriotic cyst (left column) and an endome-\ntrioid adenocarcinoma (right column). Figure 2\nshows the semiquantitative analysis of FISH signals\nfound in the epithelial cells. The proportions of\nepithelial cells with chromosomal aberrations var-\nied significantly among the different tissues. All\naneusomies occurred in a significantly larger per-\ncentage of cells in ovarian endometriosis than in the\nnormal endometrium ( Po0.001 for each aneusomy).\nFurthermore, all chromosomal aberrations were also\nfound in larger proportions of cells in ovarian\nendometriosis than in extragonadal endometriosis\n(Po0.001 for each aneusomy), whereas no clear\ndifferences were observed between extragonadal\nendometriosis and the normal endometrium. More-\nover, the frequencies of chromosomal aberrations\nincreased in a significant manner from ovarian\nendometriosis to ovarian endometrioid adenocarci-\nnoma ( Po0.001 for each aneusomy). Of note, there\nwere no significant differences between ovarian\nendometriosis associated with carcinoma and ovar-\nian endometriosis without carcinoma with respect\nto the proportions of cells with trisomies 1 and 7 and\nmonosomies 9 and 17; therefore, ovarian endome-\ntriosis with and without carcinoma was considered\nas one group in the statistical analyses.\nIn endometriosis and normal endometrium, the\nendometrial stromal cells showed the same chro-\nmosomal aberrations as the epithelial cells as well as\nsimilar differences in the proportions of aneusomic\ncells between ovarian endometriosis, extragonadal\nendometriosis, and normal endometrium. This is\nillustrated in Figure 3. The proportions of aneuso-\nmic stromal cells were significantly higher in\novarian endometriosis than in extragonadal endo-\nmetriosis and normal endometrium ( Po0.001 for\neach aneusomy). Conversely, the differences be-\ntween extragonadal endometriosis and normal en-\ndometrium were of no significance. Furthermore,\nthe comparison of Figures 2 and 3 shows that the\nfractions of aneusomic cells were lower in the\nendometrial stroma were in the corresponding\nepithelium.\nWe considered the possibility that interpretative\nissues could affect the results obtained on tissues\nwith a low rate of aneusomic cells, such as normal\nendometrium and extragonadal endometriosis. In\norder to exclude artifacts due to nucleus truncation\nin tissue sections or over-interpretation of split\nsignals,21 we compared the fractions of cells with\nchromosomal aberrations in endometriosis and the\nnormal endometrium with those found in adjacent\nnormal tissues, such as ovarian stromal cells,\nconnective tissue cells, and myometrial smooth\nmuscle cells. In the latter, one or three centromere\nsignals occurred in no more than 6% of cells, that is,\nin significantly smaller fractions of cells than in the\nepithelium and stroma of endometriosis and normal\nendometrium ( Po0.001 for each chromosome;\nFigures 2 and 3).\nInterestingly, not all normal tissues were disomic.\nWhile the ovarian stroma, connective tissue, and\nsmooth muscle did not appear to harbor significant\nnumbers of aneusomic cells, the normal endome-\ntrium, in comparison, showed substantial fractions\nof cells with trisomies 1 and 7, and monosomies 9\nand 17 ( Po0.001). The occurrence of chromosomal\naberrations in the endometrium did not depend on\nthe reproductive phase; there were no differences in\nthe amount of aneusomic cells between the endo-\nmetrium of women of reproductive age and the\natrophic endometrium of post-menopausal women.\nDiscussion\nThis study shows the presence of different chromo-\nsomal aberration rates in endometriosis at extra-\ngonadal sites, endometriosis in the ovary, ovarian\nendometrioid adenocarcinoma associated with en-\ndometriosis, and in the normal endometrium. The\nresults allow significant insights into the pathology\nof endometriosis. First, chromosomal aberrations,\nnamely trisomies 1 and 7 and monosomies 9 and 17,\nwhich are frequent in ovarian endometrioid adeno-\ncarcinoma also occur at lower rates in endometrio-\nsis. This provides evidence at the molecular level\nthat endometriosis may be a precursor of ovarian\nendometrioid adenocarcinoma and that a chromo-\nsomal instability in endometriosis may favor malig-\nnant transformation. Second, the semiquantitative\nanalysis of FISH results demonstrates a higher\nfrequency of chromosomal aberrations in ovarian\nendometriosis compared to extragonadal endome-\ntriosis. This suggests a role of the special ovarian\nmilieu in the induction of genetic changes. Finally,\nthe study shows that a semiquantitative analysis of\nFISH results allows detection of chromosomal\naberrations in small lesions and in normal tissues\nlike the endometrium that cannot be routinely\ninvestigated with other molecular techniques.\nThe present findings are consistent with and add\nto previous investigations linking ovarian cancer\nand endometriosis at the molecular level. In fact,\nendometriosis and endometrioid carcinoma were\npreviously shown to share many LOH events\ninvolving the same alleles, when located in the\nsame ovary, whereas no common LOH events were\nfound when endometriosis was present in one ovary\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1617\nModern Pathology (2006) 19, 1615–1623\n\nand the carcinoma in the contralateral one. 5,22\nFurthermore, the same X chromosome allele was\ninactivated in endometriosis and carcinoma occur-\nring in the same ovary, whereas different X chromo-\nsome alleles were inactivated when endometriosis\nwas present in one ovary and the carcinoma in the\nother one. 5 We detected higher frequencies of the\nsame genomic aberrations in ovarian endometrioid\nTable 1 Fluorescent signals in epithelial cells of extraovarian endometriosis, ovarian endometriosis not associated with carcinoma,\novarian endometriosis associated with carcinoma, ovarian endometrioid adenocarcinoma, and normal endometrium (% of nuclei with 1,\n2, and 3 signals)\nCase Number of signals\n12 312 3 1 23 1 2 3\nChromosome 1 Chromosome 7 Chromosome 9 Chromosome 17\nExtraovarian endometriosis\n1 5 47 21 4 76 20 39 61 0 40 60 0\n2 5 79 16 2 82 16 34 65 1 32 68 0\n3 3 82 15 5 79 16 33 67 0 30 70 0\n4 5 78 17 6 75 19 37 63 0 31 68 1\n5 4 77 19 5 77 18 33 66 1 33 65 2\n6 4 80 16 4 79 17 37 61 2 34 65 1\n7 5 77 18 4 77 19 34 65 1 35 65 0\n8 4 77 19 4 77 19 36 63 1 33 66 1\n9 3 72 25 3 70 27 54 46 0 52 47 1\n10 5 75 20 2 77 21 41 59 0 40 60 0\nOvarian endometriosis not associated with carcinoma\n11 3 72 25 3 70 27 54 46 0 46 53 1\n12 4 69 27 4 70 26 57 43 0 48 51 1\n13 5 67 28 4 67 29 50 48 2 48 52 0\n14 3 68 29 6 76 18 51 48 1 45 55 0\n15 4 71 25 3 69 28 51 49 0 45 53 2\n16 2 72 26 3 73 24 52 48 0 52 47 1\n17 2 71 27 4 72 24 58 42 0 56 44 0\n18 4 67 29 3 69 28 60 40 0 56 44 0\n19 3 70 27 3 73 24 57 43 0 59 40 1\n20 3 60 37 5 57 38 55 45 0 52 48 0\nOvarian endometriosis associated with carcinoma\n21 3 69 28 3 68 29 56 43 1 45 55 0\n22 4 71 25 3 70 27 55 45 0 45 55 0\n23 5 66 29 5 71 24 52 48 0 43 57 0\n24 4 96 27 2 68 30 43 17 0 44 56 0\n25 3 75 27 4 75 21 52 48 0 53 47 0\n26 3 68 29 5 68 27 53 46 1 53 47 0\n27 3 70 27 3 69 28 51 49 0 50 50 0\n28 3 72 25 3 73 24 52 48 0 52 47 1\nOvarian endometrioid adenocarcinoma\n21 4 57 39 3 61 36 65 35 0 52 47 1\n22 3 61 36 3 61 36 69 31 0 58 42 0\n23 3 56 41 3 62 35 70 30 0 58 42 0\n24 2 85 40 3 63 34 68 32 0 53 47 0\n25 2 61 37 4 62 34 65 35 0 63 37 0\n26 3 57 40 5 57 38 65 35 0 64 36 0\n27 3 57 40 3 54 43 65 35 0 66 33 1\n28 2 63 35 4 62 34 66 34 0 72 28 0\nNormal endometrium\n29 4 78 18 6 74 20 37 62 1 38 62 0\n30 4 76 20 4 77 19 32 68 0 31 69 0\n31 5 77 18 4 77 19 31 68 1 30 70 0\n32 5 73 22 4 73 23 35 63 2 38 62 0\n33 6 74 20 3 88 19 33 67 0 34 66 0\n34 5 77 18 5 76 19 30 69 1 31 69 0\n35 4 73 23 4 72 24 33 66 1 34 66 0\n36 4 72 24 5 72 23 34 65 1 37 63 0\n37 4 78 18 3 78 19 28 72 0 29 71 0\n38 4 75 21 4 75 21 30 96 1 29 71 0\n39 5 77 18 5 75 20 26 74 0 28 72 0\n40 4 74 22 5 74 21 32 68 0 34 66 0\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1618\nModern Pathology (2006) 19, 1615–1623\n\ncarcinoma than in ovarian endometriosis, which\nsuggests an expansion during carcinogenesis of\naberrant cell clones already present in endometrio-\nsis. Similarly, previous studies showed that the LOH\nevents present in both ovarian endometriosis and an\nassociated endometrioid carcinoma occurred in\nhigher incidence in the carcinoma. 5\nThere is increasing evidence from the present\nstudy and from other cytogenetic investigations that\nmultiple numerical chromosomal aberrations occur\nin endometriosis. We found that trisomies and\nmonosomies are present in all investigated endo-\nmetriosis cases. Similarly, monosomy 17 was pre-\nviously reported to occur with a 100% incidence\nin endometriosis. 11,12 In another study, trisomy 11\nand monosomy 16 were found in addition to\nmonosomy 17 in endometriosis. 10 However, in the\nlatter study, chromosomal aberrations occurred at\nlower incidences and in smaller proportions of cells\ncompared with the present results. The different\nchromosomal aberration rates between studies may\nbe due to differences in the hybridization efficacies\nTable 2 Fluorescent signals in stromal cells of extraovarian endometriosis, ovarian endometriosis not associated with carcinoma,\novarian endometriosis associated with carcinoma, and normal endometrium (% of nuclei with 1, 2, and 3 signals)\nCase Number of signals\n1 23 1 23 12 3 1 23\nChromosome 1 Chromosome 7 Chromosome 9 Chromosome 17\nExtraovarian endometriosis\n1 5 83 11 4 84 12 27 73 0 28 72 0\n2 4 85 11 3 85 12 19 81 0 20 79 1\n3 4 85 11 4 85 11 18 82 0 20 79 1\n4 5 84 11 4 84 12 20 80 0 19 81 0\n5 5 83 12 4 83 13 17 83 0 18 81 1\n6 4 85 11 3 87 10 21 79 0 19 79 2\n7 5 83 12 3 86 11 20 79 1 18 82 0\n8 5 84 11 5 84 11 21 79 0 20 79 1\n9 5 78 17 3 85 12 19 81 0 20 79 1\n10 4 84 12 5 81 14 28 72 0 27 73 0\nOvarian endometriosis not associated with carcinoma\n11 5 78 17 3 81 16 36 64 0 34 66 0\n12 4 80 16 4 81 15 42 57 1 36 63 1\n13 5 77 18 4 77 19 34 66 0 35 65 0\n14 4 80 16 6 76 18 33 66 1 34 65 1\n15 6 76 18 5 78 17 36 64 0 32 67 1\n16 4 79 17 3 82 15 39 61 0 40 59 1\n17 5 77 18 4 81 15 42 58 0 39 61 0\n18 NA NA NA NA\n19 4 78 18 6 77 17 35 65 0 44 56 0\n20 5 70 25 5 69 26 39 61 0 38 26 0\nOvarian endometriosis associated with carcinoma\n21 5 79 16 6 77 17 37 62 1 34 65 1\n22 5 79 16 5 78 17 41 59 0 33 66 1\n23 6 77 17 5 80 15 34 64 2 33 66 1\n24 5 76 19 6 77 17 29 71 0 31 69 0\n25 5 80 15 5 77 18 39 59 2 31 69 0\n26 6 77 17 6 76 18 40 60 0 39 61 0\n27 4 78 18 6 76 18 40 60 0 39 61 0\n28 NA NA NA NA\nNormal endometrium\n29 5 38 12 5 82 13 25 75 0 27 73 0\n30 5 82 13 5 83 12 22 78 0 23 77 0\n31 5 83 12 5 83 12 20 79 1 20 80 0\n32 5 82 13 5 81 14 25 75 0 27 73 0\n33 4 87 14 4 83 13 24 76 0 25 75 0\n34 6 82 12 4 83 13 20 79 1 22 78 0\n35 3 82 15 4 83 13 21 79 0 23 77 0\n36 4 82 14 5 81 14 20 80 0 22 78 0\n37 5 82 13 4 83 13 14 85 1 17 83 0\n38 5 83 12 4 84 12 18 82 0 20 80 0\n39 5 82 13 5 83 12 15 85 0 17 83 0\n40 5 83 12 3 86 11 19 81 0 20 80 0\nNA ¼ not assessable because of small number of nuclei.\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1619\nModern Pathology (2006) 19, 1615–1623\n\nof FISH procedures, interpretation of FISH signals,\nor tissues used. Overall, the current data are\nindicative of a chromosomal instability in endome-\ntriosis that could be closely related to pathogenetic\nevents leading to endometrioid cancer. In fact, there\nis increasing evidence that a chromosomal instabil-\nity contributes to malignant transformation and\ntumor progression, together with multiple single\ngene mutations of oncogenes and tumor suppressor\ngenes.8,9 Among the latter, previous studies on\nendometriosis focused on the role of tumor sup-\npressor genes and found losses of PTEN, CDKN2,\nand p53. 5,22–24\nChromosomal aberrations occur at higher fre-\nquency in ovarian endometriosis than in extragona-\ndal endometriosis. The increased susceptibility of\novarian endometriosis over extragonadal endome-\ntriosis to acquire genomic alterations may be due to\ndifferences in the environments to which ovarian\nand extragonadal endometriosis are exposed. In-\ndeed, the ovarian stroma harbors considerably\nhigher concentrations of mediators capable of indu-\ncing genomic changes, such as sex steroids, cyto-\nkines, and growth factors, than the peritoneal\nfluid,25 which may be responsible for the higher\nrate of chromosomal aberrations in ovarian endo-\nTable 3 Fluorescent signals in control cells adjacent to extraovarian endometriosis, ovarian endometriosis, and normal endometrium\n(% of nuclei with 1, 2, and 3 signals)\nCase Number of signals\n123 1 23 123 1 2 3\nChromosome 1 Chromosome 7 Chromosome 9 Chromosome 17\nConnective tissues adjacent to extraovarian endometriosis\n1 4 96 0 4 96 0 5 95 0 4 96 0\n2 5 95 0 4 96 0 5 95 0 7 93 0\n3 5 95 0 4 85 11 4 96 0 3 97 0\n4 6 94 0 5 95 0 3 97 0 4 96 0\n5 4 96 0 5 95 0 4 95 1 3 97 0\n6 5 95 0 5 95 0 3 97 0 4 96 0\n7 5 95 0 4 96 0 3 97 0 4 96 0\n8 5 95 0 5 95 0 3 97 0 5 94 1\n9 5 95 0 4 96 0 5 95 0 7 93 0\n1 0 59 50 3 9 7 0 49 60 5 9 5 0\nOvarian stromal cells\n1 1 59 50 4 9 6 0 59 50 6 9 4 0\n1 2 59 50 5 9 5 0 49 60 5 9 5 0\n1 3 59 50 5 9 5 0 79 30 6 9 4 0\n1 4 59 50 4 9 6 0 69 40 5 9 4 1\n1 5 69 40 4 9 6 0 59 50 6 9 4 0\n1 6 59 50 5 9 5 0 59 50 6 9 4 0\n1 7 59 50 4 9 6 0 49 60 7 9 3 0\n1 8 59 50 4 9 6 0 59 50 6 9 4 0\n1 9 69 40 5 9 5 0 59 50 7 9 3 0\n2 0 39 61 4 9 6 0 39 70 6 9 4 0\n2 1 59 50 5 9 5 0 59 50 5 9 5 0\n2 2 49 60 4 9 6 0 49 60 6 9 4 0\n2 3 49 60 5 9 5 0 59 50 5 9 5 0\n2 4 59 50 3 9 7 0 69 40 4 9 6 0\n2 5 49 60 5 9 5 0 39 70 5 9 5 0\n2 6 59 50 6 9 4 0 59 50 4 9 6 0\n2 7 49 60 5 9 5 0 49 60 3 9 7 0\n2 8 39 70 4 9 6 0 49 51 5 9 5 0\nMyometrium\n2 9 59 50 3 9 7 0 39 70 3 9 7 0\n3 0 49 60 5 9 5 0 49 60 3 9 7 0\n3 1 49 60 5 9 5 0 39 70 4 9 6 0\n32 NA NA NA NA\n33 NA NA NA NA\n3 4 49 42 4 9 6 0 59 50 5 9 5 0\n3 5 59 50 4 9 6 0 39 70 4 9 6 0\n3 6 39 70 4 9 6 0 59 50 4 9 6 0\n3 7 49 51 3 9 7 0 59 50 5 9 5 0\n3 8 49 60 5 9 5 0 49 60 3 9 7 0\n3 9 59 50 4 9 6 0 49 60 3 9 7 0\n4 0 39 70 3 9 7 0 59 50 5 9 5 0\nNA ¼ not assessable because of small number of nuclei.\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1620\nModern Pathology (2006) 19, 1615–1623\n\nFigure 1 FISH studies showing chromosomal aberrations in endometriosis (left column) and ovarian endometrioid adenocarcinoma\n(right column). The H&E-stained tissue sections show ( a) an endometriotic cyst composed of glandular epithelium and adjacent\nendometrial stroma, and ( d) an adenocarcinoma with endometrioid differentiation within an endometriotic cyst. FISH analysis shows in\nendometriosis in the glandular epithelium ( b) trisomy of chromosome 1 (labeled green) and trisomy of chromosome 7 (labeled red), and\n(c) monosomy of chromosome 9 (red) and monosomy of chromosome 17 (green) (insets are higher magnification of areas indicated by\narrows). Similarly, in the carcinoma, there are ( e) trisomy of chromosomes 1 (green) and 7 (red) and ( f) monosomy of chromosomes 9 (red)\nand 17 (green).\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1621\nModern Pathology (2006) 19, 1615–1623\n\nmetriosis. Consequently, this may explain why\nextrauterine endometrioid adenocarcinoma asso-\nciated with endometriosis develops much more\nfrequently in the ovary than at extragonadal sites, 26\ndespite the fact that endometriosis occurs just as\nfrequently outside the ovary as in the ovary. 27\nThe present data show that in endometriosis also\nthe stromal cells harbor chromosomal aberrations.\nAs these chromosomal aberrations are identical to\nthose found in endometrial epithelial cells, it may\nbe speculated that a chromosomal instability occurs\nin a putative common stem cell for endometrial\nepithelial and stromal cells. 28 The presence of\nchromosomal instability in endometriotic stromal\ncells suggests that the stromal component of en-\ndometriosis may also undergo malignant transfor-\nmation. This is indeed supported by the observation\nthat extrauterine endometrial stromal tumors are\nfrequently associated with endometriosis. 29,30 The\nsignificantly lower chromosomal instability in the\nendometrial stromal cells compared to the epithelial\ncells may be related to a comparatively smaller\nlikelihood of the endometrial stroma to progress to\nneoplasia and, thus, may explain the much lower\nincidence of extrauterine endometrioid stromal\ntumors with respect to extrauterine endometrioid\nadenocarcinoma.31\nFinally, it is worthy to underscore that in the\npresent study chromosomal aberrations were semi-\nquantitatively assessed as proportions of examined\ncells, rather than simply classified as present or\nabsent based on cutoff values. This approach has\nseveral advantages. 6,13 It allows the detection of\ntrisomies and monosomies only occurring in small\nfractions of cells, which can be missed if the\ncommonly used cutoff levels of 20% for polysomies\nand 40% for monosomies are applied. Furthermore,\nit enables analysis of small precursor lesions and of\nselected tissue compartments. Lastly, the compar-\nison of results obtained in different lesions enables\nthe study of molecular events involved in the\nprogression of neoplastic diseases.\nIn conclusion, the data presented in this study\ndemonstrate that endometriosis is characterized by\nseveral chromosomal aberrations and that it may be\na precursor of gonadal and extragonadal endome-\ntrioid adenocarcinoma. We also suggest that inter-\nactions between endometriosis and the specialized\novarian stroma may be involved in the pathogenesis\nof ovarian cancer in general.\nReferences\n1 Heaps JM, Nieberg RK, Berek JS. Malignant neoplasms\narising in endometriosis. Obstet Gynecol 1990;75:\n1023–1028.\n2 Feeley KM, Wells M. Precursor lesions of ovarian\nepithelial malignancy. Histopathology 2001;38:\n87–95.\nFigure 2 Semiquantitative analysis of the proportions of epithe-\nlial cells with three signals for chromosomes 1 and 7 and one\nsignal for chromosomes 9 and 17 in control tissues (Co), normal\nendometrium (En; n ¼ 12), extragonadal endometriosis (EE;\nn ¼ 10), ovarian endometriosis without carcinoma and associated\nwith carcinoma (OE; n ¼ 18), and ovarian endometrioid adeno-\ncarcinoma (Ca; n ¼ 8). The box plots indicate the percentages of\naneusomic nuclei with median value (small square), distribution\nin quartiles (large rectangle), and total range (upper and lower\nbars). Significant aneusomies are present in the normal endome-\ntrium, extragonadal endometriosis, ovarian endometriosis, and\novarian endometrioid carcinomas compared with control cells.\nThere is a significant increase in the proportions of epithelial\ncells with trisomies 1 and 7, and monosomies 9 and 17 from\nextragonadal endometriosis to ovarian endometriosis, and from\novarian endometriosis to ovarian endometrioid carcinoma.\nFigure 3 Semiquantitative analysis of the proportions of endo-\nmetrial stromal cells with three signals for chromosomes 1 and 7\nand one signal for chromosomes 9 and 17 in control tissues (Co),\nnormal endometrium (En; n ¼ 12), extragonadal endometriosis\n(EE; n ¼ 10), and ovarian endometriosis (OE; n ¼ 18). Endometrial\nstromal cells harbor small proportions of aneusomic cells. The\ndifferences in the proportions of aneusomic cells between\nextragonadal endometriosis and the normal endometrium are\nnot significant, whereas ovarian endometriosis harbors signifi-\ncantly higher proportions of aneusomic stromal cells than\nextragonadal endometriosis and the normal endometrium.\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1622\nModern Pathology (2006) 19, 1615–1623\n\n3 Vercellini P , Parazzini F , Bolis GS, et al. Endometriosis\nand ovarian cancer. Am J Obstet Gynecol 1993;169:\n181–182.\n4 Sainz de la Cuesta R, Eichhorn JH, Rice L W, et al.\nHistologic transformation of benign endometriosis to\nearly epithelial ovarian cancer. Gynecol Oncol 1996;\n60:238–244.\n5 Jiang X, Morland SJ, Hitchcock A, et al. Allelotyping of\nendometriosis with adjacent ovarian carcinoma reveals\nevidence of a common lineage. Cancer Res 1998;58:\n1707–1712.\n6K o¨ rner M, Burckhardt E, Mazzucchelli L. Different\nproportions of aneusomic cells in ovarian inclusion\ncysts associated with serous borderline tumours and\nserous high-grade carcinomas support different patho-\ngenetic pathways. J Pathol 2005;207:20–26.\n7 Auersperg N, Wong AS, Choi KC, et al. Ovarian surface\nepithelium: biology, endocrinology, and pathology.\nEndocr Rev 2001;22:255–288.\n8 Lengauer C, Kinzler KW, Vogelstein B. Genetic in-\nstabilities in human cancers. Nature 1998;396:\n643–649.\n9 Sen S. Aneuploidy and cancer. Curr Opin Oncol 2000;\n12:82–88.\n10 Shin JC, Ross HL, Elias S, et al. Detection of\nchromosomal aneuploidy in endometriosis by multi-\ncolor fluorescence in situ hybridization (FISH). Hum\nGenet 1997;100:401–406.\n11 Kosugi Y, Elias S, Malinak LR, et al. Increased\nheterogeneity of chromosome 17 aneuploidy in endo-\nmetriosis. Am J Obstet Gynecol 1999;180:792–797.\n12 Bischoff FZ, Heard M, Simpson JL. 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Comparative\ninterphase cytogenetics using FISH on human ovarian\ncarcinomas. Anticancer Res 1994;14:183–188.\n19 Brock JA, Liu WH, Smith ST, et al. Detection of\nnumerical chromosome anomalies in interphase cells\nof ovarian carcinomas using fluorescence in situ\nhybridization. Genes Chromosomes Cancer 1996;16:\n120–129.\n20 Mazzucchelli L, Burckhardt E, Hirsiger H, et al.\nInterphase cytogenetics in oncocytic adenomas and\ncarcinomas of the thyroid gland. Hum Pathol 2000;31:\n854–859.\n21 Hopman AH, van Hooren E, van de Kaa CA, et al.\nDetection of numerical chromosome aberrations using\nin situ hybridization in paraffin sections of routinely\nprocessed bladder cancers. Mod Pathol 1991;4:\n503–513.\n22 Sato N, Tsunoda H, Nishida M, et al. Loss of\nheterozygosity on 10q23.3 and mutation of the tumor\nsuppressor gene PTEN in benign endometrial cyst of\nthe ovary: possible sequence progression from benign\nendometrial cyst to endometrioid carcinoma and clear\ncell carcinoma of the ovary. Cancer Res 2000;60:\n7052–7056.\n23 Jiang X, Hitchcock A, Bryan EJ, et al. Microsatellite\nanalysis of endometriosis reveals loss of heterozygosity\nat candidate ovarian tumor suppressor gene loci.\nCancer Res 1996;56:3534–3539.\n24 Goumenou AG, Arvanitis DA, Matalliotakis IM,\net al. Microsatellite DNA assays reveal an allelic\nimbalance in p16(Ink4), GALT, p53, and APOA2 loci\nin patients with endometriosis. Fertil Steril 2001;75:\n160–165.\n25 Koninckx PR, Kennedy SH, Barlow DH. Endometriotic\ndisease: the role of peritoneal fluid. Hum Reprod\nUpdate 1998;4:741–751.\n26 Clement PB. Diseases of the peritoneum. In: Kurman RJ\n(ed). Blaustein’s Pathology of the Female Genital Tract\n5th edn. Springer: New York Berlin, Heidelberg, 2002,\npp 729–789.\n27 Stern RC, Dash R, Bentley RC, et al. Malignancy in\nendometriosis: frequency and comparison of ovarian\nand extraovarian types. Int J Gynecol Pathol 2001;20:\n133–139.\n28 Gargett CE. Identification and characterisation of\nhuman endometrial stem/progenitor cells. Austr NZ J\nObstet Gynaecol 2006;46:250–253.\n29 Baiocchi G, Kavanagh JJ, Wharton JT. Endometrioid\nstromal sarcomas arising from ovarian and extra-\novarian endometriosis: report of two cases and review\nof the literature. Gynecol Oncol 1990;36:147–151.\n30 Mourra N, Tiret E, Parc Y, et al. Endometrial stromal\nsarcoma of the rectosigmoid colon arising in extra-\ngonadal endometriosis and revealed by portal vein\nthrombosis. Arch Pathol Lab Med 2001;125:\n1088–1090.\n31 Scully RE, Young RH, Clement PB. Endometrioid\ntumors. In: Rosai J (ed). Atlas of Tumor Pathology:\nTumors of the Ovary, Maldeveloped Gonads, Fallopian\nTube, and Broad Ligament. AFIP: Washington, DC,\n1998, pp 107–140.\nChromosomal aberrations in endometriosis\nMK o¨ rner et al\n1623\nModern Pathology (2006) 19, 1615–1623","source_license":"CC0","license_restricted":false}