DNA ploidy and S-phase fraction in medullary carcinoma of the breast -a flow cytometric analysis using archival material

Summary In a population of 110 primary breast cancers with medullary features, registered in the Danish Breast Cancer Cooperative Group (DBCG) from 1977-82, we have determined ploidy and S-phase fraction (SF) by flow cytometry (FCM) on paraffin embedded tumour tissue. The distribution of DNA ploidy is not different from the distribution described for breast cancers in general. No difference is found between the subgroups of medullary and non-medullary cancer when using a new simplified histopathological definition of medullary carcinoma of the breast, recently proposed by us. When using the definition proposed by Ridolfiet al. in 1977, we find significantly more tumours with aneuploidy and high SF in the groups of typical medullary carcinoma (TMC) and atypical medullary carcinoma (AMC) than in the small group of non-medullary carcinoma (NMC), which seems a paradox, as patients with NMC have the worst prognosis. However, the number of patients in the NMC group is very small, and the percentage of aneuploid tumours is very low. In 84 protocolled patients we found no statistically prognostic importance of ploidy or SF, either in the whole group assessed or when stratifying for the histopathological subgroups. However, a prognostic influence of SF can be traced for the non-medullary cancers, according to the new definition, but not for the medullary cancers of the breast. The result emphasizes the impression of MC as being biologically different from other histological types of breast cancer.     

Medullary breast carcinoma. A reevaluation of 95 cases of breast cancer with inflammatory stroma

The hallmarks of diagnosis of medullary breast cancer (MedBC) used by the authors since 1977 have been that the tumor is well circumscribed, has syncytial architecture in greater than 75% of its surface, contains diffuse inflammatory infiltrate, has atypical nuclei, and forms no glandular pattern. In order to assess the clinical utility of these criteria, we studied a series of 95 previously untreated, surgically operable patients with breast carcinoma at the Institut Gustave-Roussy (IGR) between 1960 and 1979. A diagnosis of MedBC was initially made for these patients or suspected based on abundant inflammatory stroma observed in a histologic evaluation. Using these criteria, 26 cases were identified as typical medullary carcinoma (TMC), 23 cases as atypical medullary carcinoma (AMC), and 46 cases as nonmedullary carcinoma (NMC). The 26 cases of TMC represent a very small fraction of the total infiltrating operable breast carcinomas diagnosed at IGR during the same time period. The prognosis for these 26 patients was much more favorable than for the other groups. They had a 10-year disease-free survival of 92% compared with 53% for the AMC group and 51% for the NMC group. Neither distant metastasis nor secondary primaries of the same histology were seen. Therefore, it is possible with the use of strict histologic criteria to distinguish a group of patients with a much more favorable prognosis. This histologic diagnosis alone renders a most favorable prognosis for the patient even if other factors such as large tumor size and lymph node involvement are present and, by inference, the only therapy needed is the removal of all tumor. In contrast, atypical forms have a prognosis no different from other atypical types of breast carcinomas without inflammatory stroma, and adjuvant therapy appears to be justified if other factors warrant it.     

Medullary carcinoma of the breast, proposal for a new simplified histopathological definition. Based on prognostic observations and observations on inter- and intraobserver variability of 11 histopathological characteristics in 131 breast carcinomas with medullary features

In a previous study of 131 breast carcinomas with medullary features, we evaluated the diagnostic inter- and intraobserver variation and its prognostic implications using the criteria of typical (TMC) and atypical (AMC) medullary carcinoma of the breast put forward by Ridolfi et al. (1977). We found a considerable interobserver variation as well as intraobserver variation, with significant implication on prognosis, and concluded that the histopathological definition of MC must be sharpened and simplified in order to increase the diagnostic reproducibility. In the present study of the same population of 131 patients with breast carcinomas with medullary features we have examined inter- and intraobserver variation concerning 11 histopathological characteristics. Furthermore, we have analysed the prognostic importance of these 11 histopathological features, and the prognostic implications of the observed inter- and intraobserver variation. Based on the observations, we have eliminated criteria with poor inter-/intraobserver agreement as well as those implying no or minimal impact on the prognosis. We propose a new simplified histopathological definition of medullary carcinoma of the breast (MC), retaining reproducible, prognostically significant criteria (syncytial growth pattern and diffuse, moderate or marked mononuclear infiltration). The prognosis of MC, based on this definition, is significantly better than those of infiltrating ductal carcinomas grade II + III.     

A study of high-nuclear-grade breast cancer in Thailand: subclassification and correlation with prognostic factors and immunohistochemical study

Objectives  

To classify high-nuclear-grade breast cancer (BC) into typical medullary carcinoma (TMC), atypical medullary carcinoma (AMC), and non-medullary carcinoma (NMC), and luminal A, luminal B, and HER2, and to correlate these tumors with other prognostic factors.     

Angiogenesis and Blood Vessel Invasion as Prognostic Indicators for Node-Negative Breast Cancer

This study was undertaken to determine the value of angiogenesis and blood vessel invasion (BVI) using both Factor VIII-related antigen and elastica van Gieson staining in predicting 20-year relapse-free survival (RFS) and 20-year overall survival (OS) rates in Japanese patients with node-negative breast cancer. Two hundred and sixty patients were studied. We investigated nine factors, including angiogenesis (average microvessel count (AMC)), BVI, proliferating cell nuclear antigen (PCNA), p53, c-erbB-2, clinical tumor size (T), histological grade, tumor necrosis, and lymphatic vessel invasion (LVI). Twenty-five patients (9.6%) had recurrence and 17 patients (6.5%) died of breast cancer. Univariate analysis showed that BVI, AMC, T, histological grade, PCNA, p53, and tumor necrosis were significantly predictive of RFS or OS. Multivariate analysis showed that AMC, BVI, and T were significant independent factors for RFS or OS. Moreover, the combination of AMC/BVI was an especially significant factor for RFS or OS (P<0.0001, P=0.0003, respectively). When stratified by T, a significant impact of AMC or BVI on RFS was seen in patients with T1, T2, and T3 carcinomas. Multivariate analysis in patients with T2 carcinoma showed that both AMC and BVI were significant independent factors for RFS (P=0.0231, P=0.0388, respectively) and OS (P=0.0331 and P=0.0479, respectively). AMC, BVI, and T were independent prognostic indicators. As the combined impact of AMC/BVI is especially strong, AMC/BVI is useful in selecting high-risk node-negative breast cancer patients who may be eligible to receive aggressive adjuvant chemotherapy.     

Angiogenesis as a predictor of long-term survival for 377 Japanese patients with breast cancer

Angiogenesis, as assessed by microvessels, has been a common prognostic indicator for breast cancer in the last decade. However, the significance of angiogenesis remains controversial. This is a retrospective study of 377 Japanese patients selected from 663 breast cancer patients operated on between 1971 and 1987. To evaluate an objective method to quantify microvessel density in angiogenesis, we employed average microvessel count (AMC) per square millimeter. We investigated five factors: angiogenesis, lymph-node status (n), clinical tumor size (T), histological grade (HG), and tumor necrosis (TN), followed for a median of 10 years. Sixty-seven patients (17.8%) had recurrence and 54 patients (14.3%) died of breast cancer. Univariate analysis showed that n, T, HG, and AMC (P=0.0020) were significantly predictive of 20-year relapse-free survival (RFS). n, T, and HG were significantly associated with 20-year overall survival (OS) but AMC was borderline significant (P=0.0630). Multivariate analysis for RFS and OS showed that n, T, HG, and AMC (P<0.0001, P=0.0033, respectively) were all significant and independent prognostic factors. When stratified by T or n, a significant impact of AMC on RFS or OS was seen both in patients with T2 and T3 carcinomas or in node-negative patients, but not in T1 or node-positive patients. Thus, we can confirm angiogenesis as a significant independent prognostic factor associated with long-term survival in Japanese breast cancer patients, especially in node-negative patients and in patients with T2 and T3 carcinomas.     

Medullary carcinoma of the breast. Prevalence and prognostic importance of classical risk factors in breast cancer

In an earlier study of 235 breast cancers with medullary features, we concluded from a multivariate Cox regression analysis that only four histopathological features contained significantly positive prognostic information. In the present study, continuing our work on the same population base, we used these histological characteristics (predominantly syncytial growth pattern, no tubular component, diffuse stromal infiltration with mononuclear cells and sparse necrosis (< 25%), as diagnostic criteria for medullary carcinoma of the breast (MC). We found a significantly better prognosis for patients with MC than those with non-medullary carcinoma (NMC) or infiltrating ductal carcinoma (IDC). All tumours in the MC group were grade II or III (96% grade III). A significantly different distribution of general risk factors such as lymph node status, invasion, steroid receptor status, and menopausal status, was found between the group of MC and the control group of IDC grades II + III. Further, general risk factors, which are found to be of major prognostic importance in IDC, had little prognostic impact in MC. We found MC to be biologically unique, and patients with MC have a better than average prognosis compared to that of IDC. We propose a new histological definition of MC, but stress that prospective studies have to be performed.     

Class distribution of immunoglobulin-containing plasma cells in the stroma of medullary carcinoma of breast

Summary A class distribution of plasma cells associated with the stroma in twenty-eight cases of medullary carcinoma of the breast was investigated by an unlabeled immunoperoxidase method. The stroma of the medullary carcinomas tested was found to contain predominantly IgG plasma cells except in two cases. Stroma of the other types of breast carcinoma, including ten cases of papillo-tubular carcinoma, five cases of scirrhous carcinoma, and six cases of medullary tubular carcinoma, contained predominantly IgG plasma cells, although few plasma cells were associated with carcinoma tissues in the latter group. Plasma cells associated with control specimens, including normal breast, fibroadenoma, cystic disease, and intraductal papilloma, were found to be predominantly of IgA type. Few carcinomatous epithelial cells contained secretory components in the cytoplasm, while a number of cells positive for secretory components were observed in acinar and ductular epithelia of normal breast tissues and in benign proliferative lesions of the breast. It is suggested that the lymphoid cells infiltrating the stroma of medullary carcinoma represent a sign of host immune response against the carcinoma cells which is related to the well-known favorable prognosis associated with this tumor.     

Are all high-grade breast cancers with no steroid receptor hormone expression alike? The special case of the medullary phenotype

BACKGROUND: Medullary carcinoma (MC) of the breast is associated with favorable prognosis compared with other histological types, despite high nuclear grade, fast proliferation and lack of steroid hormone receptor expression. We retrospectively evaluated the clinical relevance of selected immunohistochemical features of tumors in three cohorts of patients with typical medullary (MC), 'atypical' medullary (AMC) or ductal (DC) breast carcinoma. PATIENTS AND METHODS: Evaluation was performed on node-negative tumor specimens from 40 patients who had either MC (12 patients), AMC (nine patients) or DC (19 patients), treated in a single institution. All had no hormonal receptor, Ki-67 > or =30%, G3, expansive pattern of growth and peritumoral lymphocytic infiltration. In addition, p27, p21 and HER2/neu overexpression, p53, cyclin E and E-cadherin expression, presence of apoptotic cells, stromal tenascin (TN), and type of immune cell infiltration (CD3- and CD68-positive cells) were assessed. RESULTS: No difference in expression of HER2/neu, p21, p27, p53, number of apoptotic cells and CD68-positive cells was detected. Lower levels of stromal TN expression were found in MC compared with DC (P=0.0007), but differences between MC and AMC were not significant (P=0.27). A higher proportion of intratumoral CD3-positive cells was seen in MC than in AMC (P=0.046). No differences were seen between MC and DC (P=0.73). With a median follow-up of 67 months, three patients with DC had relapsed in distant sites, while one patient with AMC had a second primary. Two patients with MC had reappearance of DC in the breast. CONCLUSIONS: The three distinct disease types, selected by having similar high proliferation, had similar expression of cell cycle regulators. The lower expression of TN and massive infiltration of T lymphocytes might both indicate a special interaction between tumor cells and microenvironment, important features for conferring improved prognosis through negligible invasive and metastatic potential to MC. In our series, however, patients with a previous MC are not free from the risk of developing a subsequent DC. Finally, defining AMC as a distinct entity from DC is not justified.     

Surgical treatment of carcinoma of the breast. I. Pathological finding and pattern of relapse

This is a retrospective review of 476 patients who had mastectomy for carcinoma of the breast during 1971-1980. There is a positive correlation of size of the primary tumor and the incidence of axillary nodal metastasis. Infiltrating ductal and lobular carcinoma had a significantly higher incidence of nodal metastasis (and greater change of having four or more positive nodes) than that of medullary and colloid carcinomas. Colloid carcinoma smaller than 4 cm and the less common histological subtypes (comedo, tubular, papillary carcinomas) rarely metastasizes. At a median follow-up time of 53 months, 23% of patients with infiltrating ductal, lobular, or medullary carcinomas and who did not have nodal metastasis had relapse, while 50% of those with nodal involvement had relapse. Among those who relapsed, 18% initially had only locoregional recurrence, 60% had distant metastasis, and 22% had both types.     

乳腺髓样癌的X线表现

目的 研究乳腺髓样癌的X线表现,并比较不同病理分型的X线特点,提高对该病的影像诊断水平.方法 回顾性分析经手术病理证实、有完整乳腺X线资料的乳腺髓样癌32例共33个病灶,其中典型髓样癌27个病灶,不典型髓样癌6个病灶;观察其X线特点.结果 33个病灶中表现为不伴钙化的肿块30个(90.9%),伴钙化肿块2个(6.1%)...     

Clinicopathological characteristics of triple-negative breast cancers

Triple-negative breast cancer (TNBC) is defined as a group of breast carcinomas that are negative for expression of hormone receptors and HER2. Although patients with TNBC tend to have a poor prognosis, only chemotherapy is expected to be effective because no therapeutic targets have yet been established. DNA microarray analyses have proved that TNBCs are composed of the basal-like subtype and normal breast (or unclassified) subtype, the former being correlated with an aggressive clinical course. Histological types of TNBCs are reported to be common with those of basal-like subtype, comprising high-grade invasive ductal carcinoma, no special type [solid-tubular carcinoma (or atypical medullary carcinoma), invasive ductal carcinoma with a large central acellular zone], typical medullary carcinoma, and metaplastic carcinomas. The basal-like subtype is characterized by the expression of myoepithelial/basal markers and molecular changes including TP53 gene mutations, BRCA1 inactivation, and many chromosomal alterations. New target molecules for the treatment of TNBCs are under extensive investigation, and their clinical application is awaited.     

Poorly differentiated medullary carcinoma of the stomach.

BACKGROUND. The biologic behavior of poorly differentiated medullary carcinoma of the stomach is unclear. METHODS. A clinicopathologic study on 74 poorly differentiated medullary carcinomas (PMC) and 73 nonmedullary carcinomas (NMC) of the stomach was done. PMC were defined as gastric carcinomas in which more than 50% of the tumor area contained poorly differentiated adenocarcinoma with no fibrous stroma. RESULTS. They were characterized by a location in the upper 33% of the stomach (49%), grossly expansive growth (69%), frequent vascular permeation (57%), and simultaneous liver metastasis (15%). Although the 5-year survival rate was similar for PMC and NMC, death of PMC was related more frequently to liver metastasis (47%) and less frequently to peritoneal dissemination (12%). The outcome of patients with PMC was influenced by frequent vascular permeation, extended lymph node metastasis, and simultaneous liver metastasis. CONCLUSIONS. These results indicate that PMC are characterized by expansive growth of the tumor and simultaneous or recurrent metastasis to the liver. Therefore, the biologic behavior of poorly differentiated medullary carcinoma is similar to that of well-differentiated carcinoma of the stomach.     

MMP-2 positivity and age less than 40 years increases the risk for recurrence in premenopausal patients with node-positive breast carcinoma

Node-positive breast carcinoma is associated with a poor prognosis. Some patients benefit from adjuvant chemotherapy but new treatment modalities should still be developed in order to further increase the cure rate in this patient group. Prognostic factors are needed to define patients for such studies. Here, the prognostic value of matrix metalloproteinase-2 (MMP-2) and age was evaluated in 108 premenopausal, node-positive breast carcinoma patients treated with an adjuvant chemotherapy. Expression of MMP-2 protein was studied in paraffin-embedded tissue sections from primary tumors by using specific MMP-2 monoclonal antibody in an immunohistochemical staining. Age less than 40 years predicted 5-year recurrence free survival (RFS) as unfavorable, being 74% in patients 41–49 years of age and 54% in those under age 40 (p=0.02). The 5-year RFS rate was 85% in patients with an MMP-2 negative primary tumor while it was 65% in the MMP-2 positive patient group. This difference was not, however, statistically significant (p=0.07). Correlation between hematogenous metastasis and MMP-2 positivity in breast carcinoma was demonstrated for the first time (p=0.03). A risk group for a relapse was identified using MMP-2 immunohistochemistry and age. The RFS rate in patients less than 40 years with an MMP-2 positive primary tumor was only 50% while it was 74% in other premenopausal patients (p=0.007). Young age and MMP-2 positivity may, thus, associate with early relapse in node-positive breast carcinoma.     

Tumor-infiltrating B cell immunoglobulin variable region gene usage in invasive ductal breast carcinoma

A major focus of tumor immunology is to reveal the potential role and capacity of immunocompetent cells found in different solid tumor tissues. The most abundant infiltrating cells (TIL), the T lymphocytes have been investigated in details concerning T-cell receptor usage and specificity. However, B cells have hardly been investigated in this respect, although high cellular B-cell infiltration has been correlated with improved patients’ survival in some breast carcinomas. This led to our objectives to study variable region gene usage of the tumor-infiltrating B cells in different breast carcinoma types. By defining the immunoglobulin repertoire of the tumor-infiltrating B lymphocytes in the most common invasive ductal carcinoma (IDC) of the breast we compared it to the rare medullary breast carcinoma (MBC). After phenotyping infiltrating ductal carcinomas, B cells were obtained from tumor tissue by microdissection technique. Numerous rearranged TIL-B immunoglobulin heavy chain V genes (VH) were amplified, cloned, sequenced, and comparatively analyzed. Some characteristics were found for both breast carcinoma types. The immunoglobulins produced by TIL-B in ductal carcinoma are highly matured and oligoclonal. We conclude that Ig variable region gene usage reveals similar and distinguishable characteristics of TIL-B immunoglobulin repertoires, which are representative of the nature of the immune responses in invasive ductal and medullary breast carcinomas.     

The combination of angiogenesis and blood vessel invasion as a prognostic indicator in primary breast cancer

This study was undertaken to examine the interaction between the combination of angiogenesis and blood vessel invasion (BVI) and haematogenous metastasis, and to determine the prognostic significance of that combination in predicting 20-year relapse-free survival (RFS) and overall survival (OS) rates in primary breast cancer. Five hundred and nine patients were studied. We investigated 11 factors, including average microvessel count (AMC)/BVI, lymph-node status (n), clinical tumour size (T), histological grade (HG), lymphatic vessel invasion (LVI), p53, proliferating cell nuclear antigen (PCNA), c-erbB-2, mitotic index (MI), apoptotic index, and tumour necrosis (TN). Blood vessel invasion was detected by both factor VIII-related antigen and elastica van Gieson staining. To evaluate the best objective method to quantify microvessel density in angiogenesis, AMC was employed. The rate of AMC-high and BVI-positive tumours was 32.6 and 29.3%, respectively. That of both AMC-high and BVI-positive tumours was 10.1%. Univariate analysis showed that AMC/BVI, n, T, HG, LVI, p53, PCNA, MI, and TN were significantly predictive of RFS and OS. By multivariate analysis, AMC/BVI was the strongest independent prognostic factor for 20-year RFS (relative risk (RR)=5.5; P<0.0001) and for 20-year OS (RR=4.3; P<0.0001). Lymph-node status was still considered a powerful prognostic indicator; however, the combination of AMC and BVI provided more reliable prognostic information than lymph-node status for haematogenous dissemination.     

Reliability in the classification of advanced colorectal adenomas.

In conjunction with a pooled analysis of risk factors for advanced adenomas [adenomas with severe dysplasia, carcinoma in situ (CIS), and intramucosal carcinoma], we undertook a reliability study on the pathological diagnosis of advanced adenomas. We assessed intraobserver agreement (using Kappa (kappa) as the measure of agreement) across two time periods 10 years apart with a single pathologist and interobserver agreement (using Kappa) between two pathologists rating the same slides concurrently. The study pathologists were blinded to the original case classification. We used the slides of 190 colorectal adenomatous polyp cases (104 originally diagnosed as advanced adenomas, 86 adenomas without advanced lesions) from a colonoscopy-based case-control study conducted in New York City between 1986 and 1988. We also assessed conditional agreement for 71 slides of advanced adenomas from four adenoma case-control studies conducted in different geographic regions of the United States in the 1990s. Intra- and interobserver agreement was only fair to moderate on the classification of both histological type (villous, tubulovillous, and tubular: intraobserver kappa = 0.28; 95% confidence interval (CI), 0.17-0.39; interobserver kappa = 0.48; 95% CI, 0.33-0.62) and degree of dysplasia (none/mild, moderate, severe, CIS, and intramucosal: intraobserver kappa = 0.20; 95% CI, 0.12-0.28; interobserver kappa = 0.42; 95% CI, 0.29-0.55). Using broader, rather than finer, classifications for degree of dysplasia substantially improved the reliability (interobserver agreement for high-grade dysplasia (including severe dysplasia, CIS, and intramucosal carcinoma) versus low-grade dysplasia: kappa = 0.69; 95% CI, 0.55-0.83). These findings suggest that future epidemiological studies of advanced adenomas should use broad categories, such as high-grade versus low-grade dysplasia, include central review of all slides, and take measurement error into account in sample size calculations.     

Effect of perductal paclitaxel exposure on the development of MNU-induced mammary carcinoma in female S–D rats

The amount of the immunoreactive protein for the tissue inhibitor of the matrix metalloproteinase-1 (TIMP-1) was studied prospectively from the pretreatment sera of 71 breast carcinoma patients using an enzyme-linked immunoassay (ELISA). The study consisted of patients with a primary breast carcinoma diagnosed between 1988 and 1991. The median follow-up time was more than 10years, and routine adjuvant treatment was not used in the primary treatment. High TIMP-1 (> 196ng/ml) was found to correlate with a poor relapse-free survival (RFS) in primary node-negative breast carcinoma. After 10years of the follow-up only 42% of the patients with a high preoperative serum TIMP-1-level were free of the relapse, whereas 82% of the patients with a low serum TIMP-1 enjoyed a long RFS-time (log rank p =0.009). High serum TIMP-1 also indicated poor RFS (p=0.02) and overall survival (p=0.05) in stage I breast carcinoma. In Kaplan–Meier analysis the RFS was 89% in patients with a low serum level of TIMP-1 compared to 52% in patients with a high serum concentration of TIMP-1. In conclusion, preoperative high serum TIMP-1 levels predict poor outcome in primary breast carcinoma. In multivariate analysis preoperative high serum TIMP-1 increases the risk of relapse 3.4-fold during the first 10years of follow-up in primary node-negative breast carcinoma.     

Mucinous carcinoma of the breast: A pathologic study of 82 cases

A series of 82 consecutive cases of mucinous carcinomas of the female breast was investigated for their clinical, morphological, and histochemical features and for the influence of some tumor characteristics on its prognosis. Two groups, a “pure” subtype (n=58) and a “mixed” subtype (n=24), were considered, according to the absence or the presence of concomitant areas with typical infiltrating ductal carcinoma. Eighty patients were followed with an average of 7.4 years. The actuarial survival was 58.5% at 10 years. The group of pure mucinous carcinomas showed a statistically significant better prognosis (P=0.0007) than that of the group of mixed tumors, as well as a lower percentage of axillary nodal metastasis. Tumor dimension of both pure and mixed mucinous carcinomas influenced the prognosis, since patients with T1 tumors had longer survival than those with T2 tumors (P=0.05) and the latter showed less mortality than T3 tumor cases (P=0.036). Node-negative patients also had a more favorable outcome with lower mortality than node positive patients (P=0.007). None of the T1 pure mucinous carcinomas had axillary metastasis, which may have implications for the surgical protocols. The evaluation of quantitative and qualitative content in mucosubstances did not correlate with the prognosis. However, sulfomucins were demonstrated in 30.5% of cases; this fact points to add breast carcinoma to the group of neoplasms that may present as a metastatic sulfomucin-producing adenocarcinoma. © 1995 Wiley-Liss, Inc.     

Immunohistochemical demonstration of metallothionein in normal human breast tissue and benign and malignant breast lesions

Metallothioneins (MTs) are a set of low molecular weight proteins with a high binding affinity to metal ions. MT over-expression has been recently demonstrated in invasive ductal carcinoma of the breast with poor clinical prognosis. In the present study, MTs have been immunohistochemically investigated in normal human breast tissue and a variety of benign, pre-invasive, and malignant breast lesions. In normal breast tissue, MTs were present in myoepithelial cells whereas the vast majority of luminal cells were MT negative. In lesions without increased cancer risk (adenosis and scleradenosis), MT was only immunolocalized in myoepithelial cells. In papillomas, MT was also found exclusively in myoepithelial cells. In most cases of epitheliosis, both the luminal and myoepithelial cells expressed MT. Atypicallobular hyperplasia, lobular carcinomain situ, and 13/15 invasive lobular carcinomas showed no MT over-expression. The two invasive lobular carcinomas with MT over-expression were classified as pleomorphic lobular carcinomas with apocrine differentiation. In contrast to lobular cancerization, 12/24 ductalin situ carcinomas and 9/20 invasive ductal carcinomas showed MT over-expression.In situ components found within invasive ductal carcinomas usually reflected the MT status of their invasive counterpart. It is concluded from our immunohistochemical results that breast carcinoma cases with MT overexpression arise from lesions which also show MT overexpression. Thus MT expression in carcinomas may be regarded as a genuine feature of the tumour cells and seems not to be related to endogenous or exogenous factors known to induce MT synthesis.