[Pathology of the nipple-areola complex : I. Paget's disease of the nipple, variants, and differential diagnoses]. / Pathologie der Mamillenregion : I. Morbus Paget der Mamille, Varianten und Differenzialdiagnosen.

The classical Paget's disease of the nipple is histologically characterized by tumor cell infiltration originating in intraductal or invasive breast carcinoma, immunohistologically by a frequent overexpression of HER2 and clinically by eczema-like changes of the nipple and areola. Variants with different histological, immunohistological, and clinical features are observed in nonclassical forms of Paget's disease, such as isolated Paget's disease of the nipple, anaplastic Paget's disease, Paget's disease with invasion, and pigmented Paget's disease of the nipple. In the differential diagnosis of Paget's disease, benign changes have to be considered, including Toker cell hyperplasia, nipple eczema, and rare dermatoses.

[Pathology of the nipple-areola complex : Part II. Tumors, tumor-like lesions, and supernumerary breast lesions]. / Pathologie der Mamillenregion : Teil II: Tumoren, tumorartige Läsionen und Überschussbildungen.

The nipple-areola complex is the origin of various morphologically distinct tumors and tumor-like lesions, which can be delineated from the special structures of the nipple, in particular the intramammary ducts, skin-appendages, and the intramammary stroma. Benign tumors are most frequent and this includes epithelial tumors such as mammary adenoma and syringomatous tumor of the nipple. Less commonly observed are benign mesenchymal tumors such as leiomyoma of the nipple, or tumor-like lesions like pseudo-lymphoma. With excess formations of the nipple, the different forms of polythelia and polymastia have to be considered.

Intraobserver Agreement on Histopathologic Evaluations of Core Breast Biopsies.

The number of performed core biopsies of the breast as diagnostic workup is increasing in many European countries. We measured the intraobserver variability in pathological assessment of breast core biopsies. Furthermore, we studied potential modifiers of agreement between the assessments. Two hundred and fifty-six breast biopsies were evaluated twice in a blinded fashion by two pathologists. We calculated the observed and the chance-corrected (weighted) intraobserver agreement (kappa) using the B-categorization scheme (B1: normal or not interpretable, B2: benign, B3: benign but of uncertain biological potential, B4: suspicious of malignancy, B5: malignant). The observed agreement between the first and the second assessments were 0.80 (95% CI: 0.75-0.85) for pathologist 1 and 0.81 (95% CI: 0.76-0.86) for pathologist 2. The chance-corrected agreements were 0.85 (95% CI: 0.80-0.89) and 0.81 (95% CI: 0.76-0.87), respectively. The most frequent disagreement was between B1 and B2 for pathologist 1 (N = 34 out of 50 disagreements, 68%) and between B2 and B3 for pathologist 2 (N = 23 out of 48 disagreements, 48%). Our study shows that the chance-corrected agreement between the histopathological evaluations of breast biopsies based on the B-categorization scheme is almost perfect. The level of agreement is modified by biopsy technique and by the level of suspicion of the mammographic lesion.

Influence of immunohistochemistry on the final diagnosis of breast biopsies.

AIMS: Because of the introduction of mammography screening programmes in Europe, the number of breast biopsies performed is increasing. We investigated the influence of immunohistochemistry (IHC) on the final diagnosis of breast biopsies by comparing the primary diagnoses (based on the results of haematoxylin and eosin staining only) with the final diagnoses (based on the additional information provided by IHC). METHODS AND RESULTS: We analysed the breast biopsies which were performed at the University of Halle-Wittenberg between 2006 and 2010 and for which the pathologist requested IHC for making the final diagnosis. According to the B-categorization scheme, the primary diagnosis changed in 37 of a total of 429 biopsies (8.6%). In 18 of these biopsies (48.6%) the category changed from B1-B2 to B3-B5 or vice versa, which would imply a different work-up. Only 77% of the primary diagnoses of breast cancer in situ were confirmed. CONCLUSION: IHC has a considerable influence on the final diagnosis of breast biopsies in several situations, including those in which the biopsied women are at risk of inadequate therapeutic intervention. The influence is particularly notable among those biopsies for which IHC is performed in order to assess the suspicion of breast cancer in situ.

Mammographic density and inter-observer variability of pathologic evaluation of core biopsies among women with mammographic abnormalities.

BACKGROUND: As high percentage of mammographic densities complicates the assessment of imaging findings, mammographic density may influence the histopathological evaluation of core-biopsies of the breast. We measured the influence of mammographic density on the inter-observer variability of histopathological findings of breast biopsies. METHODS: Histological slides of 695 women who underwent core biopsies of the breast at University of Halle between 2006 and 2008 were evaluated in a blinded fashion by two pathologists using the five levels of the B-categorization scheme (B1-B5). To quantify mammographic density, we used a computer-based threshold method (Madena). We calculated observed and chance-corrected agreements (weighted kappa) and 95% confidence intervals (95% CI) according to four categories of mammographic density (<10%, 10<25%, 25<50%, ≥50%). RESULTS: The weighted kappa decreased monotonically from 89.6% (95% CI: 85.8%, 93.3%) among women with less than 10% of mammographic density to 80.4% (95% CI: 69.9%, 90.9%) for women with more than 50% of mammographic density, respectively. Results of a kappa regression analysis showed that agreement of pathologists on clinically relevant categories (B1-B2 versus B3-B5) decreased with mammographic density. CONCLUSIONS: Mammographic density is a relevant modifier of the agreement between pathologists who assess breast biopsies using the B-categorization scheme. The influence of mammographic density on the inter-observer variability can be explained to some extent by varying prevalences of histological entities across B categories that have typically different inter-observer agreement. Women with high mammographic density are at higher risk of inter-observer variability compared to women with low mammographic density and should possibly undergo a second pathology review.

Factors influencing the agreement on histopathological assessments of breast biopsies among pathologists.

AIMS: It has been recommended that the histopathology results of core biopsies of the breast are categorized according to the B-categorization scheme. We measured the interobserver variability of the B-categorization of core biopsies of the breast. METHODS AND RESULTS: Core biopsies were taken among 765 women at the University of Halle between 2006 and 2008. All histological slides were reviewed in a blinded fashion by two experienced breast pathologists. We calculated observed and chance-corrected agreements (kappa) and 95% confidence intervals (CI). The prevalence of B3-B5 biopsies was 41.6%. The observed and weighted kappa agreement of the five-level B-categorization scheme was 0.87 (95% CI: 0.84 -0.89) and 0.89 (95% CI: 0.89-0.91), respectively. The most frequent disagreement was between B2 and B3 (47 of 103 disagreements, 45.6%). Overall, 49.5% of all disagreements were clinically relevant disagreements that would imply different therapeutic strategies. Agreement was modified by referral group, Breast Imaging Reporting and Data System (BIRADS) level, radiological breast density, imaging guidance and application of immunohistological staining. CONCLUSIONS: Interobserver agreement of the B-categorization scheme was high and was modified by referral status, level of radiological suspicion of breast cancer, breast density, imaging guidance of core biopsies and requirement of additional immunohistological staining.

Mucoepidermoid carcinoma of the salivary glands revisited with special reference to histologic grading and CRTC1/3-MAML2 genotyping.

Mucoepidermoid carcinoma (MEC) is the most common carcinoma of the salivary glands. Here, we have used two large patient cohorts with MECs comprising 551 tumors to study clinical, histological, and molecular predictors of survival. One cohort (n = 167), with known CRCT1/3-MAML2 fusion status, was derived from the Hamburg Reference Centre (HRC; graded with the AFIP and Brandwein systems) and the other (n = 384) was derived from the population-based Cancer Registry of North Rhine-Westphalia (LKR-NRW; graded with the AFIP system). The reliability of both the AFIP and Brandwein grading systems was excellent (n = 155). The weighted kappa for inter-rater agreement was 0.81 (95% CI 0.65-0.97) and 0.83 (95% CI 0.71-0.96) for the AFIP and Brandwein systems, respectively. The 5-year relative survival was 79.7% (95% CI 73.2-86.2%). Although the Brandwein system resulted in a higher rate of G3-MECs, survival in G3-tumors (AFIP or Brandwein grading) was markedly worse than in G1/G2-tumors. Survival in > T2 tumors was markedly worse than in those with lower T-stage. Also, fusion-negative MECs had a worse 5-year progression-free survival. The frequency of fusion-positive MECs in the HRC cohort was 78.4%, of which the majority (86.7%) was G1/G2-tumors. In conclusion, the AFIP and Brandwein systems are useful in estimating prognosis and to guide therapy for G3-MECs. However, their significance regarding young age (≤ 30 years) and location-dependent heterogeneity of in particular G2-tumors is more questionable. We conclude that CRTC1/3-MAML2 testing is a useful adjunct to histologic scoring of MECs and for pinpointing tumors with poor prognosis with higher precision, thus avoiding overtreatment.

Calcifications in digital mammographic screening: improvement of early detection of invasive breast cancers?

PURPOSE: To evaluate the relevance of calcifications for invasive breast cancer detection in population-based digital mammographic screening. MATERIALS AND METHODS: This study was approved by an independent ethics committee, and no additional informed consent was required. Prospectively documented radiologic cancer features were correlated with pathologic characteristics in 241 breast malignancies diagnosed in 24067 participating women aged 50-69 years (part of the digital German Screening Program; initial screening rate, 92%; detection rate [DR], 1.0%; recall rate [RR], 7.5%). The rates of invasive cancers detected on the basis of calcifications were analyzed against pathologic tumor categories (pT categories) and histologic grades. For comparison of the study data with results of analog screening, data from the literature regarding calcification-specific RR, DR, and positive predictive value for recall (PPV(1)) were calculated. RESULTS: The calcification-specific RR was 1.7% (416 of 24067). The calcification-specific DR for invasive cancer was 0.12% (29 of 24067), and the PPV(1) was 7.0% (29 of 416). Of all malignancies detected on the basis of calcification, 38% (29 of 77) were invasive. pT1 cancers showed an inverse association between tumor size and rate of detection on the basis of calcification; differences in rates among pT1 subcategories were statistically significant (P < .001). The proportion of grade 1 pT1 cancers detected on the basis of calcification (eight of 27) did not differ significantly from that of cancers detected on the basis of other radiologic features (46 of 108, P = .24). The calcification-specific invasive cancer DR was significantly higher for digital than for analog mammography. CONCLUSION: One-third of malignancies detected on the basis of calcifications only are invasive cancers. They tend to be smaller but not less aggressive than invasive cancers detected on the basis of other features. Compared with published results of analog screening, digital screening offers the potential to increase the rate of invasive cancers detected on the basis of calcifications in population-based mammographic screening.

Tissue expression of the nuclear progesterone receptor in male non-human primates and men.

In females, progesterone is associated with reproductive functions. In males, its role and the expression of its genomic receptor are not very well understood. In attempts to achieve a hormonal male contraceptive method, gestagens are used to downregulate gonadotropin and sperm production. It is therefore essential to understand the mechanism of action of progesterone at the molecular level in males, especially in primates. This investigation was undertaken: (a) to determine whether the genomic progesterone receptor is expressed in males; and (b) to locate it in various organs that are potential targets of gestagens. Human tissues were obtained at surgery for benign prostatic hyperplasia or prostate cancer and at autopsy. Non-human primate tissues were obtained at autopsy. This study was performed by analyzing the genomic progesterone receptor by immunohistochemistry, Western blot and RT-PCR. The nuclear progesterone receptor was expressed in pituitary and hypothalamus of both monkeys and men. In the testis progesterone receptor expression was found in a few peritubular and interstitial cells, but not in germ cells. In addition, expression was detected in the epididymis, prostate and male mammary gland. Reverse transcriptase (RT)-PCR experiments indicated that progesterone receptor A and B are expressed in all tissues analyzed. These data exclude direct genomic effects of gestagens at the spermatogenic level but indicate that a male contraceptive based on gestagens might have some effects on other tissues, such as the epididymis, prostate and mammary gland.

The potential of comparative genomic hybridization as a tool in the differential diagnosis of matrix-producing bone lesions.

Matrix-producing bone lesions consist of a wide variety of benign and malignant conditions. With respect to morphology, an overlap exists between benign and malignant bone tumors that causes difficulties in the final determination of the tumor. This study was conducted to show the potential of comparative genomic hybridization as a tool in the differential diagnosis of matrix-producing bone lesions. Thirty benign bone tumors were evaluated by conventional comparative genomic hybridization. To test its diagnostic reliability, 5 additional cases were analyzed, all with differential diagnostic difficulties related to morphology and radiology. All were ultimately diagnosed as malignant sarcomas, and unbalanced alterations were detected. In contrast benign tumors or tumor-like lesions did not reveal any chromosomal alterations. Comparative genomic hybridization is a useful adjunct in the complicated differential diagnostic algorithms of matrix-producing bone tumors.

Cytogenetic changes and loss of heterozygosity in atypical adenomatous hyperplasia, in carcinoma of the prostate and in non-neoplastic prostate tissue using comparative genomic hybridization and multiplex-PCR.

High grade prostatic intraepithelial neoplasia (PIN) and atypical adenomatous hyperplasia (AAH) are discussed to be precursors of prostate cancer (PC). Unlike high grade PIN the relation between AAH and PC is however unclear. In the present study we analyzed AAH, accompanying prostate carcinomas and carcinomas of the transitional zone after microdissection using comparative genomic hybridization (CGH) and multipelx-PCR with 10 microsatellite polymorphic markers. In every case non-neoplastic prostatic tissue was investigated for the same allelic imbalances. Two AAH showed allelic imbalances in multiplex-PCR. These imbalances did not correlate with the corresponding tumours and furthermore were different to the LOH found in the investigated prostate tumours of the transitional zone. One AAH showed loss on chromosome 22q. We found allelic imbalances in over 50% of non-neoplastic tissue adjacent to prostatic carcinoma. Our findings support the idea that AAH does not seem to be linked closely to PC and should not be considered as an obligate premalignant lesion.

Overexpression of Endothelin-A-receptor in breast cancer: regulation by estradiol and cobalt-chloride induced hypoxia.

Previous studies have demonstrated the potential significance of Endothelin (ET)-1 and its receptors, ETAR and ETBR, in the development and progression of breast cancer. The objective of this study was to assess the expression levels and potential regulation of the "ET axis" in human non-neoplastic and neoplastic breast tissue as well as in various human breast cancer cell lines. Expression of ET-1, ETAR and ETBR was evaluated in 31 neoplastic and 7 non-neoplastic breast tissue samples and in six human breast cancer cell lines using conventional and quantitative real-time RT-PCR, Western blotting and immunohistochemistry. The effects of 17beta-estradiol (E2) and cobalt-chloride (CoCl2) treatment on ET-1, ETAR and ETBR expression were studied in vitro. ETAR mRNA expression levels were found to be statistically significantly higher in breast cancer specimens than in non-neoplastic breast tissue (p<0.001). For ET-1 and ETBR mRNA expression, no significant difference was observed between the two groups. All cell lines exhibited expression of ET-1 and ETAR mRNA, whereas none showed significant ETBR mRNA expression. We observed a strong and reproducible induction of ETAR mRNA and protein expression by E2 and CoCl2 in MDA-MB-468 and BT-474 cells and in MDA-MB-453 and SK-BR-3 cells with a maximum increase after 8 and 16 h of treatment, respectively, while MCF-7 and HBL-100 cells showed a constitutive expression pattern. The present data suggest a novel mechanism in the regulation of ETAR expression in breast cancer. Based on these findings, a combination of ETAR-antagonists with adjuvant endocrine treatment seems to be a reasonable therapeutic strategy.

Vascular smooth muscle and nitric oxide synthase.

The concept of endothelium-derived relaxing factor (EDRF) put forward in 1980 by Furchgott and Zawadzki implies that nitric oxide (NO) produced by NO synthase (NOS) in the endothelium diffuses to the underlying vascular smooth muscle, where it modulates vascular tone as well as vascular smooth muscle cell (VSMC) proliferation by increasing cGMP formation with subsequent activation of cGMP-dependent protein kinase. According to this concept, VSMC do not express NOS by themselves. This attractive, simple scheme is now under considerable debate. To address this issue, we designed this study with the use of a novel supersensitive immunocytochemical technique of signal amplification with tyramide and electron microscopic immunogold labeling complemented with Western blotting, as in our recent studies demonstrating NOS in the myocardial and skeletal muscles. We provide the first evidence that, in contrast to the currently accepted view, VSMC in various blood vessels express all three NOS isoforms depending on the blood vessel type. These findings suggest an alternative mechanism by which local NOS expression may modulate vascular functions in an endothelium-independent manner.

Endothelin-1-, endothelin-A-, and endothelin-B-receptor expression is correlated with vascular endothelial growth factor expression and angiogenesis in breast cancer.

PURPOSE: Endothelin-1 (ET-1) and its receptors (ET(A)R and ET(B)R), referred to as the endothelin (ET) axis, are overexpressed in breast carcinomas, and influence tumorigenesis and tumor progression by various mechanisms, including angiogenesis. The objective of the study was to clarify if expression of the ET axis participates in angiogenesis of breast carcinoma EXPERIMENTAL DESIGN: We analyzed expression of ET-1, ET(A)R, ET(B)R, and vascular endothelial growth factor (VEGF) immunohistochemically in 600 tissue array specimens from 200 paraffin-embedded breast carcinomas performing tissue microarray technology. Microvessel density (MVD) was determined by counting microvessels (identified by factor VIII) in each core specimen. RESULTS: Moderate or strong immunostaining was observed for ET-1 in 25.4%, for ET(A)R in 43.7%, and for ET(B)R in 22.2% of breast carcinomas. Of all cases, 44.7% showed significant expression of VEGF. MVD varied between different tumor specimens (range, 0-80; median, 17). We observed a statistically significant correlation between MVD and ET expression status with higher MVD in ET-positive tumors. Moreover, expression of VEGF was found more frequently in tumors with overexpression of the ET axis (each P < 0.001). Staining of VEGF was correlated positively with MVD CONCLUSIONS: These results indicate that increased ET-1, ET(A)R, and ET(B)R expression is associated with increased VEGF expression and higher vascularity of breast carcinomas and, thus, could be involved in the regulation of angiogenesis in breast cancer. Our findings provide evidence that the expression pattern of the ET-axis and in particular of ET(A)R may have clinical relevance in future antiangiogenic targeted therapies for breast cancer.

Expression of endothelin-1, endothelin-A, and endothelin-B receptor in human breast cancer and correlation with long-term follow-up.

PURPOSE: Endothelin-1 (ET-1) is overexpressed in breast carcinomas and stimulates tumor cell growth in an autocrine and paracrine fashion via its receptors, ET(A)R and ET(B)R. In this study, we evaluated the expression of ET-1 and ET receptors in breast carcinomas and determined its clinical and prognostic significance. EXPERIMENTAL DESIGN: We analyzed expression of ET-1, ET(A)R, and ET(B)R in 176 breast carcinomas using a semiquantitative immunohistochemical approach. Statistical analysis of clinicopathological variables such as pT stage, pN stage, hormone receptor status, Her-2/neu amplification, histological grade, and long-term follow-up data were performed. RESULTS: We observed a moderate to strong cytoplasmic staining for ET-1 in 69 (43.1%), for ET(A)R in 74 (46.5%), and for ET(B)R in 86 (53.4%) cases of primary breast cancer. A correlation was found between increased ET-1 expression and its receptors with several clinicopathological parameters that characterize aggressive types of breast cancer, with the exception of increased ET(A)R and ET(B)R expression with positive estrogen receptor status. Elevated expression of ET-1, ET(A)R, and ET(B)R was more common in breast carcinomas of patients with lower disease-free survival time and overall survival. In addition, a statistically significant correlation was observed between ET(A)R expression and reduced disease-free survival time (P = 0.041). Interestingly, the prognostic impact of ET(A)R expression was shown to be more pronounced in the subgroup of patients with a putative favorable prognosis according to classic prognostic factors. CONCLUSIONS: Therefore, analysis of ET(A)R expression may improve the prediction of relapse and death and facilitate an individually based risk-directed adjuvant therapy in breast cancer patients.

Relationship between HER2 status and proliferation rate in breast cancer assessed by immunohistochemistry, fluorescence in situ hybridisation and standardised AgNOR analysis.

Lack of standardisation and inaccuracy in HER2 test results may adversely influence patient evaluation and therapy selection. In the present study we applied immunohistochemistry (IHC) using the A0485 and CB11 antibodies and fluorescence in situ hybridisation (FISH) for detection of HER2 in 74 routinely processed breast carcinoma specimens. The rapidity of cellular proliferation was assessed by standardised AgNOR analysis and compared with HER2 status. Protein over-expression was found in 30/74 cases by A0485 and in 20/74 by CB11 antibodies, while amplification was detected in 22/74 carcinomas by FISH. Twenty-seven of 74 tumours were high-level AgNOR expressors (mean AgNOR area >3.369 microm2), 19 of which revealed amplification. The highest concordance between results was achieved by FISH and CB11-IHC (97%), the concordance between FISH and A0485-IHC was 89 and 84% between FISH and AgNOR quantity, respectively. The overall concordance between A0485 and CB11-IHC was 85% with 10 incongruent cases, all scored 2+ by A0485 and 0/1+ by CB11. Eight of the discordant tumours were non-amplified by FISH and 7 were low AgNOR-expressors. Our results indicate that using CB11 antibody, a nearly complete agreement can be achieved between HER2 IHC and FISH in diagnostic paraffin material. Moreover, in 2+ positive IHC cases, the AgNOR analysis may represent an additional tool to select patients as candidates for Herceptin therapy due to the strong negative predictor value.

Analysis of cyclooxygenase-2 expression in human breast cancer: high throughput tissue microarray analysis.

PURPOSE: The objective of this study was to evaluate breast carcinomas for the expression of cyclooxygenase-2 (Cox-2) using a tissue microarray (TMA) and to determine its clinical and prognostic relevance. METHODS: We analyzed Cox-2 expression in 600 samples from 200 breast carcinomas immunohistochemically performing TMA technology and semiquantitative analysis. Results were correlated with various clinicopathological variables and follow-up data. Expression of estrogen receptor, progesterone receptor, Ki-67, and Her-2/neu-oncogene was analyzed and correlated with Cox-2 status. RESULTS: We observed a moderate or strong cytoplasmic staining for Cox-2 in 78 (40.6%) of breast carcinomas. Increased Cox-2 expression corresponded to higher pT stage ( P=0.038), amplification of Her-2/neu ( P=0.032), lymphovascular invasion ( P=0.006), a high MIB-1 labeling index (LI) ( P<0.001), and histological grading ( P=0.013). We also observed an inverse relationship between strong Cox-2 expression and estrogen and progesterone receptor content of tumors ( P=0.037 and P=0.010). However, we could not demonstrate a significant association between Cox-2 staining and overall survival or disease free survival time. CONCLUSIONS: These results suggest that Cox-2 expression is significantly associated with less differentiated and more aggressive breast carcinomas and might therefore be a useful prognostic indicator as well as a target for therapy.

Endothelin-1, Endothelin-A- and Endothelin-B-receptor expression in preinvasive and invasive breast disease.

Endothelin-1 (ET-1) is overexpressed in breast carcinomas and influences via its receptors (ETAR and ETBR) transformation, differentiation and growth processes in the human breast, but little is known about the ET expression in breast cancer precursors. On this basis we evaluated the expression of ET-1, ETAR and ETBR in a series of breast carcinomas, ductal (DCIS) and lobular carcinoma in situ (LCIS) and normal breast tissue by immunohistochemical (IH) methods. IH staining of ET-1, ETAR and ETBR was performed in 88 invasive breast carcinomas, with adjacent carcinoma in situ and concomitant normal breast tissue. Moderate or strong cytoplasmic immunostaining was observed for ET-1 in 33.3%, for ETAR in 45.3% and for ETBR in 55.7% of invasive breast carcinomas. Comparative analysis of invasive cancer (CA), concomitant carcinoma in situ (CIS) and normal breast epithelium (NBE) revealed a stepwise increase of ET-1 and ETAR expression in the sequence NBE < CIS < CA. ETBR expression tended to be slightly higher in CIS than in CA (NBE versus CIS and NBE versus CA, for ETAR and ETBR, p<0.001, respectively; NBE versus CA for ET-1, p=0.035). Our data suggest that the expression of ET-1, ETAR and ETBR correlates with the acquisition of malignant potential and may be used as a prognostic indicator of aggressive behaviour and invasive potential of premalignant breast lesions.

Comparative genomic hybridization in cartilaginous tumors.

Genetic aberrations in cartilaginous tumors have not yet been well characterized. We analyzed the molecular-chromosomal aberrations in 10 chondrosarcomas (four Grade-3 tumors, four Grade-2 tumors and two Grade-1 tumors) and in three benign cartilaginous tumors (two enchondromas and one chondromyxoid fibroma). Genomic imbalances were detected in 9 out of 10 cases of chondrosarcomas. The median number of changes was 7.0 per tumor (range 0-23) and the gain-to-loss ratio was 1:1.4. The most frequent gains involved 7q, 5p, or 21q and the most frequent losses were 17p, 13q, 16p, or 22q. The three benign cartilaginous tumors each had two (0 gains and two losses), six (one gain and five losses) and eight (one gain and seven losses) chromosomal aberrations. Both of the gains occurred on 13q21 and losses were frequently observed on chromosomes 19 and 22q in all three cases. Loss of chromosomes 16p, 17p, 22q, or 19 loss were common in both chondrosarcomas and benign cartilaginous tumors. However, aberrations from chromosomes 2 to 11, 14, 15, 18, or 21 were detected only in chondrosarcomas. Therefore, although the number of aberrations between benign and malignant cartilaginous tumors appears to be similar, these two entities may be differentiated by determining which chromosomes are affected.