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Two Cases of Fibrocystic Breast Disease with Polysomy 18 as the Sole Clonal Cytogenetic Abnormality
Two Cases of Fibrocystic Breast Disease with Polysomy 18 as the Sole Clonal Cytogenetic Abnormality Bettina Staats, Ulrich Bonk, Gabriela Gohla, Sabine Bartnitzke, and Jörn Bullerdiek
ABSTRACT: In the present study, we describe the occurrence of numerical alterations of chromosome 18 in two cases of benign fibrous/fibrocystic tumors of the breast, both of which were studied by conventional cytogenetic investigations and one of which was additionally tested by fluorescence in situ hybridization with the use of an alphoid centromeric probe specific for chromosome 18. Case 1 showed a tetrasomy 18 in 2 of 33 metaphases as the only clonal chromosomal aberration. Case 2 revealed both trisomy and tetrasomy 18 as clonal alterations in metaphases and interphase nuclei. © Elsevier Science Inc., 1998 INTRODUCTION Fibrocystic disease, or mastopathia fibrosa cystica, is the most common benign lesion of the breast in women aged 35–54 years. The terms are used to describe a heterogenous group of abnormalities that may occur separately or together. Clinically, it is linked to palpable breast masses that fluctuate with the menstrual cycle, and it may be associated with pain or tenderness. Histologically, the term fibrocystic disease includes macroscopic and microscopic cysts, stromal fibrosis, apocrine metaplasia, and a variety of proliferative lesions [1]. The system suggested by Dupont and Page [2] separates the various components of fibrocystic disease into three groups with different relative risk for the subsequent development of breast cancer: 1. Nonproliferative lesions; 2. Proliferative lesions without atypia; and 3. Atypical hyperplasias. Our two samples of examined fibrocystic disease were both considered to belong to the group of nonproliferative lesions, which is characterized by cysts, papillary apocrine changes, epithelial-related calcification, and mild hyperplasia of the usual type. Despite their relatively frequent occurrence, cytogenetic data of fibrocystic disease are rather rare. To the best
From the Center for Human Genetics and Genetic Counseling, University of Bremen (B. S., S. B., J. B.), Bremen, Germany; and the Institute for Pathology, Central Hospital Bremen-Nord (U. B., G. G.), Bremen, Germany. Address reprint requests to: Dr. J. Bullerdiek, Center for Human Genetics and Genetic Counseling, University of Bremen, Leobener Str. ZHG, D-28359 Bremen, Germany. Received July 22, 1997; accepted September 17, 1997. Cancer Genet Cytogenet 103:91–94 (1998) Elsevier Science Inc., 1998 655 Avenue of the Americas, New York, NY 10010
of our knowledge, only a few cases with clonal chromosomal abnormalities have been reported until now [3–6]. Herein we report the results of our cytogenetic studies on two such cases, both having polysomy 18. CASE REPORTS Case 1 A 44-year-old female was admitted to the hospital because of a nodule in her breast. The tumor was surgically removed and revealed the histologic features of a fibrous mastopathy with a simple cyst and tissue of a scar. Case 2 A nodule was detected in the left breast of a 64-year-old woman without a previous history of neoplasia. The size of the tumor was 3 3 2 cm and histologically it showed a fibrocystic mastopathy without atypia (Fig. 1). MATERIALS AND METHODS Cell cultures, cytogenetic preparation, and G-banding were performed according to routine methods [7, 8]. The cell culture medium used was TC 199 with Earle’s salts supplemented with 20% fetal calf serum and 2% penicillin (10,000 U/mL)/streptomycin (10,000 mg/mL). The tumor karyotypes were described according to the International System for Human Cytogenetic Nomenclature [9]. Fluorescence in situ hybridization (FISH) on metaphase spreads was carried out according to a protocol described elsewhere [10] with some minor modifications [11, 12]. We used a chromosome 18–specific alphoid centromeric DNA sequence (D18Z1, Oncor, Gaithersburg, MD) as a probe. For examination of the slide after FISH, a Zeiss Axioplan fluorescence microscope (Oberkochem, Germany)
0165-4608/98/$19.00 PII S0165-4608(97)00388-9
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B. Staats et al.
Figure 1 Histologic appearance of case 2 showing (a) a fibrocystic mastopathy without atypia and (b) enlargement of a part of (a) showing a ductus (H&E staining).
was used. Results were processed and recorded with the Power Gene Karyotyping System (PSI, Halladale, UK). RESULTS Case 1 A total of 33 metaphases were fully karyotyped. Tetrasomy 18 was found as the only clonal abnormality in 2
metaphases (Fig. 2). One metaphase showed three normal and one deleted chromosome 18 [48,XX,118,1del(18)(q?)]. A normal karyotype was found in 30 cells. Case 2 A total of 19 G-banded metaphases were fully karyotyped: 12 metaphases showed an apparently normal karyotype, 5 metaphases were characterized by trisomy 18 as the sole
93
Polysomy 18 and Fibrocystic Breast Disease
Figure 2 Representative G-banded karyotype of the fibrous mastopathy (case 1) showing a tetrasomy 18 as the clonal aberration: 48,XX,118,118.
clonal chromosomal abnormality, and 2 metaphases showed tetrasomy 18. Additionally, 46 metaphases were checked for the presence of the trisomy/tetrasomy 18: 12 metaphases showed only two chromosomes 18; in 17 metaphases, three chromosomes 18 were found; and, in 17 metaphases, a tetrasomy 18 was detected. Because of these results, additional metaphase spreads and interphase nuclei, respectively, were subjected to FISH. Two hundred interphase nuclei and 41 additional metaphases were scored for the number of signals obtained by using a chromosome 18 centromeric probe. In 30 metaphases, we observed four signals (Fig. 3). The remaining 11 metaphase spreads showed two signals. In 33% of the nuclei, we observed three signals; in 16.5%, four; and, in 1%, more than four signals. The remaining nuclei showed two signals (44.5%) or one signal (5%). A cytogenetic preparation of lymphocytes from a normal healthy donor served as a control. One hundred metaphases and 150 interphase nuclei were checked. There were no cells exceeding two signals, and only a low percentage of 0/100 (metaphases) and 3/150 (interphase nuclei) of cells, respectively, revealed one signal, whereas the remaining cells showed exclusively two signals. DISCUSSION Fibrocystic disease of the breast is a clinically important lesion because of its high frequency, the ability of some of its subtypes to simulate the clinical and microscopical appearance of carcinoma, and the possible relation of some of its forms to carcinoma [2, 13]. Despite their frequent occurrence, little is known about clonal chromosomal abnormalities of fibrocystic disease. Belda et al. [3] described a benign fibrous tumor of the breast with a clonal chromo-
somal rearrangement t(4;14)(q24–q25;q24.3) in 10 of 23 examined metaphases. With a combined cytogenetic/immunohistochemical study they were able to show that cells with the clonal abnormality were of mesenchymal origin. The cytogenetic study of Dietrich et al. [5] on 30 benign lesions of the breast revealed clonal chromosomal aberrations in 16 cases, 6 of which have repeatedly been
Figure 3 FISH analysis of a metaphase and interphase nuclei of the fibrocystic mastopathy without atypica (case 2), using a chromosome 18–specific alphoid centromeric DNA probe. The arrows indicate chromosomes 18.
94 seen in breast carcinomas as well, as for example, del(1) (q12), del(3)(p12p14), or der(16)t(1;16)(q10;p10). Dal Cin et al. [6] reported a case of benign fibrocystic disease without epithelial hyperplasia with an interstitial deletion of the long arm of chromosome 6 [del(6)(q21q25)] in all 20 G-banded metaphases examined. Six of 29 samples of fibrocystic disease studied by Petersson et al. [4] revealed clonal chromosomal alterations, 5 of them showing structural aberrations. In regard to a 53-year-old woman who underwent reduction mammoplasty, the sample histologically showed fibrosis, fibroadenosis, and sclerosing adenosis and it was marked cytogenetically by a trisomy 18 in 2 of 61 metaphases. In the present study, we also detected clonal trisomy/tetrasomy 18 in two cases of fibrous/fibrocystic disease. Interestingly, trisomy 18 is also a frequent finding in malignant tumors of the breast [14–18] and of breast tissue surrounding invasive breast cancer [19]. In these reports, trisomy 18 was either a primary or a secondary karyotypic alteration. In our two cases presented here and in the study of Petersson et al. [4], trisomy 18 was the only karyotype alteration. Although in the cases presented here we were not able to unequivocally demonstrate that the polysomy 18 occurred in epithelial cells, the occurrence of trisomy 18 in benign hyperplasias as well as in carcinomas of the breast suggests that this aberration plays an important role in early stages of the transformation of epithelial cells of the breast. REFERENCES 1. Schnitt SJ, Connolly JL (1991): Pathology of benign breast disorders. In: Breast Diseases, ed. 2. JR Harris, S Hellman, IC Henderson, DW Kline, eds. J.B. Lippincott Company, Philadelphia, pp. 15–20. 2. Dupont WD, Page DL (1985): Risk factors for breast cancer in women with proliferative breast disease. N Engl J Med 312:146–151. 3. Belda F, Lester SC, Pinkus JL, Pinkus GS, Fletcher JA (1993): Lineage-restricted chromosome translocation in a benign fibrous tumor of the breast. Hum Pathol 24:923–927. 4. Petersson C, Johansson B, Pandis N, Gorunova L, Ingvar C, Idvall I, Mandahl N, Mitelman F (1994): Clonal chromosome aberrations in fibrocystic breast disease associated with increased risk of cancer. Int J Oncol 5:1207–1210. 5. Dietrich CU, Pandis N, Teixeira MR, Bardi G, Gerdes AM, Andersen JA, Heim S (1995): Chromosome abnormalities in benign hyperproliferative disorders of epithelial and stromal breast tissue. Int J Cancer 60:49–53. 6. Dal Cin P, Moerman P, Christiaens MR, Van den Berghe H
B. Staats et al.
7. 8.
9. 10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
(1996): Observation of a deletion of the long arm of chromosome 6 in benign fibrocystic disease of the breast constitutes a challenging problem. Genes Chromosom Cancer 16:68–71. Seabright M (1971): A rapid banding technique for human chromosomes. Lancet 1:971–972. Bullerdiek J, Leuschner E, Taquia E, Bonk U, Bartnitzke S (1993): Trisomy 8 as a recurrent clonal abnormality in breast cancer? Cancer Genet Cytogenet 65:64–67. ISCN (1995): An International System for Human Cytogenetic Nomenclature. F Mitelman, ed. S. Karger, Basel. Kievitz T, Dauwerse JG, Wiegant J, Devilee P, Breuning MH, Cornelisse CJ, van Ommen GJB, Pearson PL (1990): Rapid subchromosomal localization of cosmids by non-radioactive in situ hybridization. Cytogenet Cell Genet 53:134–136. Schoenmakers EFPM, Kools PFJ, Mols R, Kazmierczak B, Bartnitzke S, Bullerdiek J, Dal Cin P, De Jong PJ, Van den Berghe H, Van de Ven WJM (1993): Physical mapping of chromosome 12q breakpoints in lipoma, pleomorphic salivary gland adenoma, uterine leiomyoma, and myxoid liposarcoma. Genomics 20:210–222. Kools PFJ, Roebroek AJM, Van de Velde HJK, Marynen P, Bullerdiek J, Van de Ven WJM (1993): Regional mapping of the human NSP gene to chromosome 14q21–q22 by fluorescence in situ hybridization. Cytogenet Cell Genet 66:48–50. Fentiman IS (1990): Risk factors for benign breast disease. In: Benign Breast Disease. JA Smallwood, J Taylor, eds. E. Arnold, London, pp. 121–138. Devilee P, Theirry RF, Kievitz T, Kolluri R, Hopman AHN, Willard HF, Pearson PL, Cornelisse CJ (1988): Detection of chromosomal aneuploidy in interphase nuclei from human primary breast tumors using chromosome-specific repetitive DNA probes. Cancer Res 48:5825–5830. Geleick D, Müller H, Matter A, Torhorst J, Regenass U (1990): Cytogenetics of breast cancer. Cancer Genet Cytogenet 46: 217–228. Pandis N, Heim S, Bardi G, Idvall I, Mandahl N, Mitelman F (1993): Chromosome analysis of 20 breast carcinomas: Cytogenetic multiclonality and karyotypic-pathologic correlations. Genes Chromosom Cancer 6:51–57. Bullerdiek J, Bonk U, Staats B, Leuschner E, Gohla G, Ebel T, Bartnitzke S (1994): Trisomy 18 as the first chromosomal abnormality in a medullary breast cancer. Cancer Genet Cytogenet 73:75–78. Rohen C, Meyer-Bolte K, Bonk U, Ebel T, Staats B, Leuschner E, Gohla G, Caselitz J, Bartnitzke S, Bullerdiek J (1995): Trisomy 8 and 18 as frequent clonal and single-cell aberrations in 185 primary breast carcinomas. Cancer Genet Cytogenet 80:33–39. Bonk U, Staats B, Bartnitzke S, Gohla G, Hanisch P, Bullerdiek J (1994): Cytogenetic studies of breast tissue surrounding invasive breast cancer. In: Second European Congress on Senology: Breast Disease. E Kubista, A Staffen, C Zielinski, eds. Monduzzi, Bologna, pp. 393–396.
ABSTRACT: In the present study, we describe the occurrence of numerical alterations of chromosome 18 in two cases of benign fibrous/fibrocystic tumors of the breast, both of which were studied by conventional cytogenetic investigations and one of which was additionally tested by fluorescence in situ hybridization with the use of an alphoid centromeric probe specific for chromosome 18. Case 1 showed a tetrasomy 18 in 2 of 33 metaphases as the only clonal chromosomal aberration. Case 2 revealed both trisomy and tetrasomy 18 as clonal alterations in metaphases and interphase nuclei. © Elsevier Science Inc., 1998 INTRODUCTION Fibrocystic disease, or mastopathia fibrosa cystica, is the most common benign lesion of the breast in women aged 35–54 years. The terms are used to describe a heterogenous group of abnormalities that may occur separately or together. Clinically, it is linked to palpable breast masses that fluctuate with the menstrual cycle, and it may be associated with pain or tenderness. Histologically, the term fibrocystic disease includes macroscopic and microscopic cysts, stromal fibrosis, apocrine metaplasia, and a variety of proliferative lesions [1]. The system suggested by Dupont and Page [2] separates the various components of fibrocystic disease into three groups with different relative risk for the subsequent development of breast cancer: 1. Nonproliferative lesions; 2. Proliferative lesions without atypia; and 3. Atypical hyperplasias. Our two samples of examined fibrocystic disease were both considered to belong to the group of nonproliferative lesions, which is characterized by cysts, papillary apocrine changes, epithelial-related calcification, and mild hyperplasia of the usual type. Despite their relatively frequent occurrence, cytogenetic data of fibrocystic disease are rather rare. To the best
From the Center for Human Genetics and Genetic Counseling, University of Bremen (B. S., S. B., J. B.), Bremen, Germany; and the Institute for Pathology, Central Hospital Bremen-Nord (U. B., G. G.), Bremen, Germany. Address reprint requests to: Dr. J. Bullerdiek, Center for Human Genetics and Genetic Counseling, University of Bremen, Leobener Str. ZHG, D-28359 Bremen, Germany. Received July 22, 1997; accepted September 17, 1997. Cancer Genet Cytogenet 103:91–94 (1998) Elsevier Science Inc., 1998 655 Avenue of the Americas, New York, NY 10010
of our knowledge, only a few cases with clonal chromosomal abnormalities have been reported until now [3–6]. Herein we report the results of our cytogenetic studies on two such cases, both having polysomy 18. CASE REPORTS Case 1 A 44-year-old female was admitted to the hospital because of a nodule in her breast. The tumor was surgically removed and revealed the histologic features of a fibrous mastopathy with a simple cyst and tissue of a scar. Case 2 A nodule was detected in the left breast of a 64-year-old woman without a previous history of neoplasia. The size of the tumor was 3 3 2 cm and histologically it showed a fibrocystic mastopathy without atypia (Fig. 1). MATERIALS AND METHODS Cell cultures, cytogenetic preparation, and G-banding were performed according to routine methods [7, 8]. The cell culture medium used was TC 199 with Earle’s salts supplemented with 20% fetal calf serum and 2% penicillin (10,000 U/mL)/streptomycin (10,000 mg/mL). The tumor karyotypes were described according to the International System for Human Cytogenetic Nomenclature [9]. Fluorescence in situ hybridization (FISH) on metaphase spreads was carried out according to a protocol described elsewhere [10] with some minor modifications [11, 12]. We used a chromosome 18–specific alphoid centromeric DNA sequence (D18Z1, Oncor, Gaithersburg, MD) as a probe. For examination of the slide after FISH, a Zeiss Axioplan fluorescence microscope (Oberkochem, Germany)
0165-4608/98/$19.00 PII S0165-4608(97)00388-9
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B. Staats et al.
Figure 1 Histologic appearance of case 2 showing (a) a fibrocystic mastopathy without atypia and (b) enlargement of a part of (a) showing a ductus (H&E staining).
was used. Results were processed and recorded with the Power Gene Karyotyping System (PSI, Halladale, UK). RESULTS Case 1 A total of 33 metaphases were fully karyotyped. Tetrasomy 18 was found as the only clonal abnormality in 2
metaphases (Fig. 2). One metaphase showed three normal and one deleted chromosome 18 [48,XX,118,1del(18)(q?)]. A normal karyotype was found in 30 cells. Case 2 A total of 19 G-banded metaphases were fully karyotyped: 12 metaphases showed an apparently normal karyotype, 5 metaphases were characterized by trisomy 18 as the sole
93
Polysomy 18 and Fibrocystic Breast Disease
Figure 2 Representative G-banded karyotype of the fibrous mastopathy (case 1) showing a tetrasomy 18 as the clonal aberration: 48,XX,118,118.
clonal chromosomal abnormality, and 2 metaphases showed tetrasomy 18. Additionally, 46 metaphases were checked for the presence of the trisomy/tetrasomy 18: 12 metaphases showed only two chromosomes 18; in 17 metaphases, three chromosomes 18 were found; and, in 17 metaphases, a tetrasomy 18 was detected. Because of these results, additional metaphase spreads and interphase nuclei, respectively, were subjected to FISH. Two hundred interphase nuclei and 41 additional metaphases were scored for the number of signals obtained by using a chromosome 18 centromeric probe. In 30 metaphases, we observed four signals (Fig. 3). The remaining 11 metaphase spreads showed two signals. In 33% of the nuclei, we observed three signals; in 16.5%, four; and, in 1%, more than four signals. The remaining nuclei showed two signals (44.5%) or one signal (5%). A cytogenetic preparation of lymphocytes from a normal healthy donor served as a control. One hundred metaphases and 150 interphase nuclei were checked. There were no cells exceeding two signals, and only a low percentage of 0/100 (metaphases) and 3/150 (interphase nuclei) of cells, respectively, revealed one signal, whereas the remaining cells showed exclusively two signals. DISCUSSION Fibrocystic disease of the breast is a clinically important lesion because of its high frequency, the ability of some of its subtypes to simulate the clinical and microscopical appearance of carcinoma, and the possible relation of some of its forms to carcinoma [2, 13]. Despite their frequent occurrence, little is known about clonal chromosomal abnormalities of fibrocystic disease. Belda et al. [3] described a benign fibrous tumor of the breast with a clonal chromo-
somal rearrangement t(4;14)(q24–q25;q24.3) in 10 of 23 examined metaphases. With a combined cytogenetic/immunohistochemical study they were able to show that cells with the clonal abnormality were of mesenchymal origin. The cytogenetic study of Dietrich et al. [5] on 30 benign lesions of the breast revealed clonal chromosomal aberrations in 16 cases, 6 of which have repeatedly been
Figure 3 FISH analysis of a metaphase and interphase nuclei of the fibrocystic mastopathy without atypica (case 2), using a chromosome 18–specific alphoid centromeric DNA probe. The arrows indicate chromosomes 18.
94 seen in breast carcinomas as well, as for example, del(1) (q12), del(3)(p12p14), or der(16)t(1;16)(q10;p10). Dal Cin et al. [6] reported a case of benign fibrocystic disease without epithelial hyperplasia with an interstitial deletion of the long arm of chromosome 6 [del(6)(q21q25)] in all 20 G-banded metaphases examined. Six of 29 samples of fibrocystic disease studied by Petersson et al. [4] revealed clonal chromosomal alterations, 5 of them showing structural aberrations. In regard to a 53-year-old woman who underwent reduction mammoplasty, the sample histologically showed fibrosis, fibroadenosis, and sclerosing adenosis and it was marked cytogenetically by a trisomy 18 in 2 of 61 metaphases. In the present study, we also detected clonal trisomy/tetrasomy 18 in two cases of fibrous/fibrocystic disease. Interestingly, trisomy 18 is also a frequent finding in malignant tumors of the breast [14–18] and of breast tissue surrounding invasive breast cancer [19]. In these reports, trisomy 18 was either a primary or a secondary karyotypic alteration. In our two cases presented here and in the study of Petersson et al. [4], trisomy 18 was the only karyotype alteration. Although in the cases presented here we were not able to unequivocally demonstrate that the polysomy 18 occurred in epithelial cells, the occurrence of trisomy 18 in benign hyperplasias as well as in carcinomas of the breast suggests that this aberration plays an important role in early stages of the transformation of epithelial cells of the breast. REFERENCES 1. Schnitt SJ, Connolly JL (1991): Pathology of benign breast disorders. In: Breast Diseases, ed. 2. JR Harris, S Hellman, IC Henderson, DW Kline, eds. J.B. Lippincott Company, Philadelphia, pp. 15–20. 2. Dupont WD, Page DL (1985): Risk factors for breast cancer in women with proliferative breast disease. N Engl J Med 312:146–151. 3. Belda F, Lester SC, Pinkus JL, Pinkus GS, Fletcher JA (1993): Lineage-restricted chromosome translocation in a benign fibrous tumor of the breast. Hum Pathol 24:923–927. 4. Petersson C, Johansson B, Pandis N, Gorunova L, Ingvar C, Idvall I, Mandahl N, Mitelman F (1994): Clonal chromosome aberrations in fibrocystic breast disease associated with increased risk of cancer. Int J Oncol 5:1207–1210. 5. Dietrich CU, Pandis N, Teixeira MR, Bardi G, Gerdes AM, Andersen JA, Heim S (1995): Chromosome abnormalities in benign hyperproliferative disorders of epithelial and stromal breast tissue. Int J Cancer 60:49–53. 6. Dal Cin P, Moerman P, Christiaens MR, Van den Berghe H
B. Staats et al.
7. 8.
9. 10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
(1996): Observation of a deletion of the long arm of chromosome 6 in benign fibrocystic disease of the breast constitutes a challenging problem. Genes Chromosom Cancer 16:68–71. Seabright M (1971): A rapid banding technique for human chromosomes. Lancet 1:971–972. Bullerdiek J, Leuschner E, Taquia E, Bonk U, Bartnitzke S (1993): Trisomy 8 as a recurrent clonal abnormality in breast cancer? Cancer Genet Cytogenet 65:64–67. ISCN (1995): An International System for Human Cytogenetic Nomenclature. F Mitelman, ed. S. Karger, Basel. Kievitz T, Dauwerse JG, Wiegant J, Devilee P, Breuning MH, Cornelisse CJ, van Ommen GJB, Pearson PL (1990): Rapid subchromosomal localization of cosmids by non-radioactive in situ hybridization. Cytogenet Cell Genet 53:134–136. Schoenmakers EFPM, Kools PFJ, Mols R, Kazmierczak B, Bartnitzke S, Bullerdiek J, Dal Cin P, De Jong PJ, Van den Berghe H, Van de Ven WJM (1993): Physical mapping of chromosome 12q breakpoints in lipoma, pleomorphic salivary gland adenoma, uterine leiomyoma, and myxoid liposarcoma. Genomics 20:210–222. Kools PFJ, Roebroek AJM, Van de Velde HJK, Marynen P, Bullerdiek J, Van de Ven WJM (1993): Regional mapping of the human NSP gene to chromosome 14q21–q22 by fluorescence in situ hybridization. Cytogenet Cell Genet 66:48–50. Fentiman IS (1990): Risk factors for benign breast disease. In: Benign Breast Disease. JA Smallwood, J Taylor, eds. E. Arnold, London, pp. 121–138. Devilee P, Theirry RF, Kievitz T, Kolluri R, Hopman AHN, Willard HF, Pearson PL, Cornelisse CJ (1988): Detection of chromosomal aneuploidy in interphase nuclei from human primary breast tumors using chromosome-specific repetitive DNA probes. Cancer Res 48:5825–5830. Geleick D, Müller H, Matter A, Torhorst J, Regenass U (1990): Cytogenetics of breast cancer. Cancer Genet Cytogenet 46: 217–228. Pandis N, Heim S, Bardi G, Idvall I, Mandahl N, Mitelman F (1993): Chromosome analysis of 20 breast carcinomas: Cytogenetic multiclonality and karyotypic-pathologic correlations. Genes Chromosom Cancer 6:51–57. Bullerdiek J, Bonk U, Staats B, Leuschner E, Gohla G, Ebel T, Bartnitzke S (1994): Trisomy 18 as the first chromosomal abnormality in a medullary breast cancer. Cancer Genet Cytogenet 73:75–78. Rohen C, Meyer-Bolte K, Bonk U, Ebel T, Staats B, Leuschner E, Gohla G, Caselitz J, Bartnitzke S, Bullerdiek J (1995): Trisomy 8 and 18 as frequent clonal and single-cell aberrations in 185 primary breast carcinomas. Cancer Genet Cytogenet 80:33–39. Bonk U, Staats B, Bartnitzke S, Gohla G, Hanisch P, Bullerdiek J (1994): Cytogenetic studies of breast tissue surrounding invasive breast cancer. In: Second European Congress on Senology: Breast Disease. E Kubista, A Staffen, C Zielinski, eds. Monduzzi, Bologna, pp. 393–396.