The myoepithelium in human breast carcinoma

Adenomyoepithelioma of the Breast. A Case Report

Adenomyoepithelioma is a proliferative disorder of both epithelial and myoepithelial cells. This lesion may be found in salivary glands, skin appendages and, very rarely, in the mammary gland. Adenomyoepithelioma was first described in 1970 and very few cases have so far been reviewed in the literature. This paper reports the clinical, histological and immunohistochemical characteristics of an adenomyoepithelioma in a 24 year old woman; to our knowledge this is the first published case in such a young patient. The clinical feature suggested a fibroadenoma. A more complete study of the excised tumor tissue by immunohistochemical and ultrastructural analysis proved that the correct diagnosis was adenomyoepithelioma. Whether adenomyoepithelioma is a benign or a low-grade malignant lesion is still controversial and, therefore, the therapeutic approach is not well defined.

Adenomyoepithelioma of the Breast

Adenomyoepithelioma of the breast is an uncommon tumor characterized by the presence of both epithelial and myoepithelial cells; its first full description was published in 1970 by Hamperl.

A 45-year-old woman presented a left breast lump that had been palpable for 4 weeks. There was no family history of breast cancer. Neither axillary nor supraclavicular lymph nodes were palpable. Craniocaudal mammography showed a 1.6 cm, well-defined nodule with several punctate intranodular calcifications in the subareolar region of the left breast. Color Doppler sonogram showed an ovoid, well-defined, homogeneous hypoechoic subareolar nodule with prominent peripheral vessels in the 6 o'clock position of the left breast. Operation was arranged and intraoperative frozen section examination revealed proliferation of round, oval or tubular glandular elements with intervening islands and bands of polygonal myoepithelial cells. Adenomyoepithelioma of the breast was the impression. Wide excision with adequate removal of the tumor and preservation of the left breast contour was successfully achieved. The diagnosis of adenomyoepithelioma of the breast was confirmed by immunohistochemical studies.

Expression of vascular endothelial growth factor and caspase-3 in mucinous breast carcinoma and infiltrating ductal carcinoma-not otherwise specified, and the correlation with disease-free survival

Mucinous breast carcinoma (MBC) is a rare type of breast cancer, but it has been infrequently studied due to its associated good prognosis. Vascular endothelial growth factor (VEGF) and caspase-3 have been identified to be prognostic factors of infiltrating ductal carcinoma-not otherwise specified (IDC-NOS), but their expression in MBC has not been reported. In the present study, the expression of caspase-3 and VEGF in MBC and IDC-NOS were assessed by immunohistochemistry. Scoring was conducted based on staining intensity and percentage of positive cells. Based on the scores of caspase-3 and VEGF expression, all patient samples were divided into two groups: Low expression (score of 0-5) or high expression (score of 6-12). In total, 42.59% of MBC patients exhibited a high VEGF score compared with 61.67% of the IDC-NOS group (P<0.05). Furthermore, 57.41% of MBC patients exhibited high caspase-3 expression compared with only 33.33% of IDC-NOS patients (P<0.05). VEGF expression in MBC was associated with age, nodal status and tumor-node-metastasis (TNM) stage. Cox univariate analysis showed that higher VEGF expression, positive nodal status and higher TNM stage were associated with shorter disease-free survival (DFS). The Kaplan-Meier method showed that higher VEGF expression in MBC was associated with worse DFS times, while Cox multivariate analysis showed that only TNM stage was significantly associated with DFS. VEGF and caspase-3 expression varied in the MBC and IDC-NOS samples, but neither was directly correlated with DFS in the MBC patients.

Malignant myoepithelioma of the breast: A case report and review of the literature

Malignant myoepithelioma of the breast is an extremely rare tumor composed entirely or almost entirely of malignant spindle cells with myoepithelial differentiation. Only a limited number of case reports have been descibed to date; therefore the biological behavior and treatment outcomes of this rare tumor have not been clearly determined. Herein, we present a case of a 74-year-old woman who was admitted with inflammatory-like cancer of the breast, presenting with invasion of the chest wall and axillary lymph node metastasis at the time of diagnosis. The histological examination revealed a tumor composed of epithelioid and spindle cells with moderate to marked nuclear atypia, with foci of hemorrhage and necrosis. The tumor cells were immunoreactive for vimentin, p63, p53, CD10, cytokeratin (CK)8/18, CKAE1-3 and S-100. Finally, a diagnosis of myoepithelial carcinoma of the breast was established. Neoadjuvant chemotherapy was first administered and proved to be ineffective. Due to locoregional progression that was associated with the development of an abscess and subsequent excessive bleeding, a palliative mastectomy was performed. Postoperatively, one more cycle of systemic chemotherapy was administered. However, the patient experienced an early relapse to the chest wall and succumbed to septic shock due to persistent local infection. The aggressiveness and chemoresistance of the tumor in this case was consistent with the existing bibliography.

Myoepithelial Carcinoma: A Rare Neoplasm of the Breast

BACKGROUND: Malignant myoepitheliomas of the breast are extremely rare. There has been a limited number of published reports of myoepithelial carcinomas originating from the breast. CASE REPORT: We describe a malignant myoepithelioma of the breast in a 56-year-old woman. Histological examination showed polygonal epithelioid cells and spindle cells with moderate to marked nuclear atypia. Immunohistochemistry showed reactivity in the spindle cells for smooth muscle actin, cytokeratin (AE1/AE3), and p63, indicating a myoepithelial cell lineage of tumor cells. The patient underwent radical surgical excision of the lesion and axillary lymph node dissection. She demonstrated no evidence of recurrence over an 11-month follow-up. CONCLUSIONS: We suggest myoepithelial carcinomas of the breast be managed with appropriate surgical clearance. A multidisciplinary approach is usually required.

Myoepithelial cells: any role in aspiration cytology smears of breast tumors?

AIMS AND OBJECTIVE

To study the role of myoepithelial (ME) cells in distinguishing benign, proliferative breast diseases (PBD) and frank malignant breast lesions.

MATERIALS AND METHODS

In this study, histology proven 71 cases of fine needle aspiration cytology (FNAC) of palpable breast lesions were selected. There were 30 invasive carcinomas (24 infiltrating duct carcinoma and 6 infiltrating lobular carcinoma), 25 cases of benign lesion (21 fibroadenomas and 4 fibrocystic lesions) and 11 proliferative breast diseases (other than carcinoma in situ) and five cases of carcinoma in situ. The number of ME cells were estimated in respect to 1000 ductal cells. In every case at least 20 high power fields (x 40) were studied. Quantitative estimation of ME cell was correlated with the final diagnosis. Corresponding histopathology cases were also evaluated for diagnostic confirmation along with the pattern of distribution of ME cells. The ME cells were also quantitated on histopathology sections on smooth muscle actin (SMA) immunostained sections.

RESULTS

The mean number of ME cells per 1000 ductal cells on cytology smears was 5.1 +/- 5.5, 30.8 +/- 25, 28.3 +/- 20.2, and 38.4 +/- 38.8 in malignant, carcinoma in situ, PBD and benign breast lesions respectively. The non parametric Mann Whitney test showed significant difference in number of the ME cells between benign and malignant groups (p < .000), PBD and malignant groups (p < .000) and carcinoma in situ and malignant group (p < .001). However, it was insignificant between benign and PBD group, and PBD and carcinoma in situ (p > .01). In SMA stained histopathology sections, ME cell in benign, PBD, carcinoma in situ and malignant cases were 741.12 +/- 248, 238 +/- 172, 121.6 +/- 115 and 15.6 +/- 25.1 respectively. Statistical analysis showed significantly different number of ME cell between benign versus PBD group, carcinoma in situ and malignant group. It was also significant between PBD versus malignant, and carcinoma in situ versus malignant (p < .001, Mann Whitney test). However number of ME cell was not significant between PBD versus carcinoma in situ.

CONCLUSION

The number of ME cell in breast lesions may be helpful in distinguishing PBD versus invasive malignant tumors on FNAC smears. However it is not helpful to distinguish benign lesions versus PBD.

Myoepithelial cells: good fences make good neighbors

The mammary gland consists of an extensively branched ductal network contained within a distinctive basement membrane and encompassed by a stromal compartment. During lactation, production of milk depends on the action of the two epithelial cell types that make up the ductal network: luminal cells, which secrete the milk components into the ductal lumen; and myoepithelial cells, which contract to aid in the ejection of milk. There is increasing evidence that the myoepithelial cells also play a key role in the organizational development of the mammary gland, and that the loss and/or change of myoepithelial cell function is a key step in the development of breast cancer. In this review we briefly address the characteristics of breast myoepithelial cells from human breast and mouse mammary gland, how they function in normal mammary gland development, and their recently appreciated role in tumor suppression.

Breast cell invasive potential relates to the myoepithelial phenotype

On the basis of marker profile, the majority of breast carcinomas are thought to be derived from luminal epithelial cells; however, a subgroup of tumours with more mesenchymal characteristics are associated with a worse prognosis. The hypothesis of our study is that some breast carcinomas exhibit myoepithelial rather than pure mesenchymal differentiation and that acquisition of myoepithelial characteristics confers an aggressive phenotype. Pure luminal epithelial cells and fibroblasts are readily distinguished by many markers but distinguishing between myoepithelial and fibroblast cell lineages is more problematic. The markers found to be most discriminating in our study were CK14, alpha6beta4 integrin and the myoepithelial-associated desmosomal cadherin DSg3. These markers were applied to a series of breast cell lines and purified normal breast cell populations and the expression profile related to in vitro invasive behaviour. This demonstrated that expression of one or more myoepithelial markers by tumour cells (MDA MB 231, MDA MB 468, MDA MB 436) was associated with a high invasive capacity compared with cells with a pure luminal phenotype (MCF-7, T47D, ZR75). To address why myoepithelial characteristics are associated with higher invasion, the in vitro behaviour of normal myoepithelial cells and two other nontumourigenic breast cell lines (MCF-10A, HBL100) was also analysed. Primary myoepithelial cells from normal human breast exhibit a high invasive capacity when grown at low density, suggesting that invasive capacity is part of the myoepithelial phenotype. In keeping with this, both nontumourigenic cell lines exhibited features of the myoepithelial phenotype and a high invasive capacity. These results suggest that tumours that exhibit a myoepithelial phenotype may be clinically more aggressive because a high invasive capacity is intrinsic to the myoepithelial phenotype.

Immunohistochemical distinction of invasive from noninvasive breast lesions: a comparative study of p63 versus calponin and smooth muscle myosin heavy chain

Identification of myoepithelial cells using antibodies to cytoskeletal proteins, such as smooth muscle myosin heavy chain (SMM-HC) and calponin, can play an important role in distinguishing invasive carcinoma from its histologic mimics. However, antibodies to these proteins may also cross-react with stromal myofibroblasts and vascular smooth muscle cells. It has recently been demonstrated that myoepithelial cells express the nuclear protein, p63, a member of the p53 gene family. We compared the patterns of reactivity of antibodies with p63, calponin, and SMM-HC on 85 breast lesions, including 11 cases of sclerosing adenosis, 33 cases of ductal carcinoma in situ, including 10 that showed microinvasion, 6 cases of lobular carcinoma in situ, and 35 cases of infiltrating ductal carcinoma. All three antibodies were positive on the vast majority of myoepithelial cells in all cases. A small minority of cases showed focal gaps in the revealed myoepithelial cell layer, reflected in discontinuous positive immunostaining around noninvasive epithelial nests (including ductal carcinoma in situ). No case showed p63 expression by myofibroblasts or vascular smooth muscle cells, whereas myofibroblasts expressed, in 8% and 76% of cases, SMM-HC and calponin, respectively. Although no tumor cell reactivity was noted with antibodies to calponin or SMM-HC, tumor cells in 11% of cases showed at least focal p63 expression. And although antibodies to p63 offer excellent sensitivity and increased specificity for myoepithelial detection relative to antibodies to calponin and SMM-HC, they have the following diagnostic limitations: 1) they occasionally demonstrate an apparently discontinuous myoepithelial layer, particularly around ductal carcinoma in situ, and 2) they react with a small but significant subset of breast carcinoma tumor cells. p63 may represent a myoepithelial marker that can complement or replace SMM-HC and/or calponin in the analysis of difficult breast lesions.

Primary breast myoepithelial cells exert an invasion-suppressor effect on breast cancer cells via paracrine down-regulation of MMP expression in fibroblasts and tumour cells

In normal breast and ductal carcinoma in situ, myoepithelial cells form an incomplete layer separating the epithelial compartment from the stromal environment. Transition to invasive disease is marked by penetration of the myoepithelial-basement membrane (BM) interface. One mechanism involved in tumour invasion is breakdown of extracellular matrices by matrix metalloproteinases (MMPs). It was hypothesized that myoepithelial cells may modulate tumour invasion by controlling MMP gene expression, both in tumour cells and in peri-ductal fibroblasts. To investigate this, myoepithelial cells from normal breast were purified and characterized and their effect on tumour cell invasive potential was assessed. The effect on MMP gene expression of breast cancer cells cultured alone or in combination with primary normal breast fibroblasts was also analysed using RT-PCR with ELISA quantitation, with zymographic analysis to measure enzyme activity. Normal breast myoepithelial cells significantly reduced invasion by the breast cancer cell lines MCF-7, T47D, MDA-MB 231, and MDA-MB 468 when they were cultured alone or in the presence of a fibroblast population. Reduced invasion was associated with changes in MMP gene expression. In those tumour cells expressing MMP, there was a significant down-regulation of MMP-2 (MDA-MB 468, p<0.001), MMP-9 (MDA-MB 231, p=0.05; MDA-MB 468, p<0.001), and MT1-MMP (p<0.001 for both MDA-MB 231 and MDA-MB 468). Myoepithelial cells also caused a significant decrease in MMP gene expression in co-cultured fibroblasts. Furthermore, this was associated with reduced gelatinolytic activity as identified by zymography. This study demonstrates for the first time that primary myoepithelial cells from normal breast reduce breast cancer cell invasion and that this is mediated via modulation of both tumour cell and fibroblast function. This emphasizes the importance of the myoepithelial cell in controlling the breast microenvironment and focuses on the potential significance of the loss of this population with disease progression.

Elastosis in lung carcinoma: immunohistochemical, ultrastructural and clinical studies

Elastosis is the pathological finding of focal deposits of elastic fibers in abnormal amounts within tissue. It is well described in the case of infiltrating carcinoma of the breast, but elastosis in lung carcinoma has not been previously documented in detail. We investigated the characteristics of elastosis in lung carcinoma with light and electron microscopies, and immunohistochemistry for alpha-1-antitrypsin. A total of 184 surgically resected primary lung carcinomas were studied. Elastosis was detected in adenocarcinomas (85/106), squamous cell carcinomas (11/60) and adenosquamous carcinomas (5/7), but not in small-cell carcinomas (n = 4) or large-cell carcinomas (n = 5). The degree of elastosis in each case was divided into one of five grades, graded as 3+ to 1-. The score of elastosis was significantly higher in adenocarcinoma than that in squamous-cell carcinoma (P<0.01). In the cases of adenocarcinoma, the mean score of elastosis in the well-differentiated type (WD n = 43) was higher than that in the moderately differentiated (MD) (n = 39; P = 0.012) and poorly differentiated (PD) types (n = 24; P<0.01). The mean score of elastosis in MD adenocarcinoma was also higher than that in the PD type (P<0.01). Light- and electron-microscopic analyses revealed that these elastic fibers in elastosis were composed of aggregates of thick mature and fine immature elastic fibers, and were positive for alpha-1-antitrypsin. It is suggested that both degraded elastic fibers and newly synthesized fibers are contained in the elastosis of lung carcinoma. Although no significant evidence was detected to suggest any correlation between elastosis and the degree of tumor invasion, the survival curves of adenocarcinomas with elastosis showed a significantly improved prognosis than of those without elastosis in the cases of stages IA and IB (n = 52; P = 0.026).

Comparative genomic hybridization analysis of myoepithelial carcinoma of the breast

Although there seems to be a common stem cell for the two epithelial cell types in the breast, the vast majority of breast cancers exhibit a luminal phenotype. Pure myoepithelial carcinomas are rare. We report our findings of genetic alterations in these tumors. We have analyzed 10 cases of pure myoepithelial cell carcinomas using laser capture microdissection and comparative genomic hybridization. The mean number of changes was 2.1 (range 0-4), compared with a mean of 8.6 (range 3.6-13.8) in unselected ductal carcinomas. Common alterations included loss at 16q (3/10 cases), 17p (3/10), 11q (2/10), and 16p (2/10), regions also commonly deleted in ductal carcinomas. The single case in which both pure myoepithelial carcinoma and invasive ductal carcinoma was present showed 2 alterations in the myoepithelial tumor (losses at 17p and 17q), whereas the invasive ductal component showed 15 alterations (5 gains and 9 losses), including loss at 17p. The sharing of 17p loss in myoepithelial and ductal carcinoma is consistent with a common stem cell model in the breast. The relatively few genetic alterations in otherwise aggressive neoplasms suggests that myoepithelial tumors may be a good model for the delineation of genes important in breast tumorigenesis.

Distribution of calponin and smooth muscle myosin heavy chain in fine-needle aspiration biopsies of the breast

The cell types that may be present in any fine-needle aspiration biopsy (FNAB) of breast include epithelial cells (EC), myoepithelial cells (MEC), bipolar stromal cells (BSC), vascular pericytes/endothelial cells (VPEC), and adipose cells (AC). The recognition of most of these benign cellular elements in aspirates of the breast is relatively straightforward, based on distinct cytomorphologic criteria. However, there is controversy regarding the recognition of MEC because BSC are often referred to as MEC by cytopathologists. It is important to identify MEC in breast aspirates, because their presence has been associated with benign epithelial proliferations. In this study we used immunocytochemical methods on archival cytology slides with antibodies specific for MEC, calponin, and smooth muscle myosin heavy chain (SMMHC), to determine the distribution of MEC in FNAB of the breast and to ascertain the distribution of MEC in in situ and invasive carcinomas. Fifteen benign FNABS of breast and corresponding tissue biopsies were obtained along with 10 malignant FNABS and corresponding excisional breast biopsies from 1989-1993. Calponin and SMMHC antibodies were used on archival alcohol-fixed Papanicolaou-stained direct smears as well as the corresponding tissue sections. The distribution and pattern of positive immunostaining with both antibodies were recorded on the benign elements and the carcinomas for both cytologic and histologic slides. Benign breast tissues demonstrated strong continuous immunostaining for calponin and SMMHC of MEC. The interlobular stromal cells as well as intralobular stromal cells showed no immunostaining with either antibody. In cytologic preparations, MEC staining with calponin and SMMHC appeared as spindle cells between epithelial cells or along the edges of the epithelial groups. The bipolar stromal cells did not stain with either antibody. The tissues with DCIS (ductal carcinoma in situ) often showed the presence of MEC with strong calponin immunostaining, but sometimes the immunostaining was discontinuous or entirely absent around markedly dilated ducts. The SMMHC antibody was invariably negative, with architectural DCIS in dilated ducts. Two cases of DCIS with prominent periductal fibrosis or inflammation were positive for calponin, but the periductal stromal cells were calponin- and SMMHC-negative. Invasive carcinoma was negative for both calponin and SMMHC, but areas of DCIS were often positive in a discontinuous pattern. In conclusion, 1) Benign cellular elements from breast tissue FNAB showed strong continuous decoration of MEC with both calponin and SMMHC. Vascular pericytes and vascular smooth muscle were positive for both antibodies, but these cells were not observed in the FNAB. Benign proliferative epithelium showed no local increase in MEC with either antibody. Bipolar stromal cells in tissue and smears did not stain for MEC antibodies. 2) BSC did not correspond morphologically to MEC, and were not decorated with calponin or SMMHC. 3) Calponin-positive MEC were commonly associated with in situ ductal lesions, although they may at times have been discontinuous or absent entirely. DCIS may be recognized in FNAB by the presence of calponin-positive MEC associated with tumor cell groups. 4) Invasive carcinomas were invariably negative for MEC with these antibodies.

Relaxin: a pleiotropic hormone

1. Relaxin is a peptide hormone of about 6000 Da belonging to the insulin family. Like insulin, relaxin is composed by two disulfide-linked chains, termed the A and B chains, the B chain bearing the receptor interaction site. 2. Relaxin is produced primarily by the corpus luteum, in both pregnant and nonpregnant females. It attains the highest plasma levels during pregnancy. In this condition, relaxin is also produced by the decidua and placenta. In males, relaxin is synthesized in the prostate and released in the seminal fluid. An additional source of relaxin has recently been identified in the heart atria. 3. Relaxin has a broad range of biologic activities, some of which have been known for a long time. These latter ones include: (a) the induction of collagen remodeling and consequent softening of the tissues of the birth canal in view of delivery; (b) the inhibition of uterine contractile activity; (c) the stimulation of growth and differentiation of the mammary gland. 4. In more recent years, novel sites of relaxin action have been recognized. In particular, it has been shown that relaxin: (a) regulates growth and differentiation of breast cancer cells in culture; (b) promotes dilation of blood vessels in several organs and tissues, including the uterus, the mammary gland, the lung and the heart; (c) has a chronotropic action on the heart; (d) inhibits the release of histamine by mast cells, thus being able to counteract experimental allergic asthma; (d) depresses aggregation of platelets and their release by megakaryocytes; (e) influences the secretion of hormones by the pituitary gland; and (f) contributes to the regulation of fluid balance. 5. Concerning the mechanisms of action of relaxin, stimulation of nitric oxide generation, with consequent rise in intracellular cyclic GMP levels, and stimulation of cyclic AMP production have been demonstrated to occur in the target cells and organs. 6. It may be expected that the next decade will provide answers about the utility of relaxin, in terms of insight into the actual physiologic functions of relaxin in the animal kingdom and especially in man, in view of possible therapeutic use of relaxin or relaxin-derived drugs in human disease, especially considering that human recombinant relaxin is now available for clinical experimentation.

Differentiation of breast cancer cells in vitro is promoted by the concurrent influence of myoepithelial cells and relaxin

Our previous studies showed that relaxin promotes differentiation of MCF-7 breast adenocarcinoma cells. In the current investigation, we aimed to elucidate whether the effect of the hormone is potentiated when MCF-7 cells are grown together with myoepithelial cells, thus creating a microenvironment reminiscent of the organised tissue architecture of the mammary parenchyma in vivo. The findings obtained reveal that most MCF-7 cells cultured alone have an undifferentiated, blast-like phenotype, only a minority showing a more differentiated phenotype with more organelles and rudimentary intercellular junctions. When co-cultured with myoepithelial cells more MCF-7 cells acquire ultrastructural features consistent with a more differentiated phenotype, such as a rich organellular complement, apical microvilli and intercellular junctions. When relaxin was added to the co-cultures, the ultrastructural signs of differentiation could be observed in even more MCF-7 cells and became more pronounced than in the absence of the hormone, judged by the appearance of a clear-cut polarisation of cytoplasmic organelles, an almost continuous coat of apical microvilli and numerous intracellular pseudolumina.

Lobular involvement in human breast carcinoma

One hundred twenty-nine cases of breast carcinoma were examined in order to clarify the occurrence of lobular involvement with regard to stromal invasion. Lobular involvement was clearly recognized in 56 cases (43%) having discernible portions of intraductal carcinoma components. The process of lobular involvement was first recognizable as an extension of a few carcinoma cells from intralobular ducts into the acinar lumina. Progressive accumulation of the carcinoma cells resulted in marked swelling and distortion of the involved lobules. During the process, perilobular myoepithelial cells (actin-positive cells) were stretched and disappeared. Subsequently, breaks in the basement membranes were also observed, resulting in stromal invasion of carcinoma cells. The lobular involvement was classified into common and round varieties, possibly reflecting different growth activities of the carcinoma cells. The stromal invasion was initiated by peripheral budding or focal necrosis of the involved lobules. The latter pattern was often observed in comedo carcinoma. It was thus revealed that in breast carcinomas the terminal ductal-lobular units are quite often involved and can become sites of extraductal invasion.

Generation of monoclonal antibodies against human carcinosarcoma cell line for identification of myoepithelium and basement membrane

An immunohistochemical method is described for identification of myoepithelial cells and basement membrane for cryostat tissue sections of normal, benign, and in situ carcinomas of the breast using two monoclonal antibodies 155C1 and 155D10 generated against human breast carcinosarcoma cell line HS578T. In the majority of infiltrating ductal carcinomas of the breast, there was a discontinuity in the myoepithelial cell layer, as a result an intact basement membrane could not be visualized. The reactivity of these two monoclonal antibodies might prove useful in the study of myoepithelial differentiation antigens and in the delineation of basement membrane. Among the other types of tissues studied, prominent staining was present with soft tissue tumors like leiomyosarcoma and synovial sarcoma.

Immunohistochemical localization of myoepithelial cells and basement membrane in normal, benign and malignant human breast lesions

Distributions of actin and type IV collagen were investigated immunohistochemically as markers for myoepithelial cells and basement membranes. Carnoy's and Methacarn-fixed, paraffin-embedded tissues from 103 human breast lesions from 103 patients were examined; 65 with carcinomas, 27 with mastopathies, 9 with fibroadenomas and 2 with phyllodes tumours. Fifty-five samples of the normal mammary gland tissue adjacent to tumours were also included for comparison. In normal breast and benign breast diseases, type IV collagen was identified around the mammary glandular cells and actin-positive cells were demonstrated to attach to basement membranes. In noninvasive carcinomas, type IV collagen was found as a continuous lining around a cell nest, while actin-positive cells were usually absent in ductal but quite numerous in lobular carcinomas. In invasive carcinomas, type IV collagen was fragmented or absent and actin-positive cells were very uncommon around the fragmentary basement membranes. These results suggest that the different distributions of myoepithelial cells and basement membrane material is useful in the differential diagnosis of surgical pathology of the breast.

Immunolocalization of a human basal epithelium specific keratin in benign and malignant breast disease

This report describes the immunocytochemical localization of a human basal- or myoepithelial-specific anti-keratin antibody in benign and malignant breast disease. Reactivity patterns with this antibody have demonstrated the lack of myoepithelial or basal epithelial participation in most benign breast specimens examined including those displaying cystic disease, fibrosis, or hyperplasia. However, in specimens of sclerosing adenosis, strong reactivity with the majority of cells in most ducts suggests a major participation of the myoepithelial cell type. Analysis of 118 breast carcinoma specimens has demonstrated strong, homogeneous reactivity in 4% of the specimens, suggesting a role for the basal epithelial cell in malignancy of the human mammary gland and implications for the prognosis of such tumors. Antigenic characterization of the malignant and benign mammary specimens which are uniformly reactive with the antibody has demonstrated the presence of a 51 kd keratin polypeptide not found in the non-reactive specimens.

Establishment of monoclonal antibodies reactive with epithelial and myoepithelial cells in the breast

Monoclonal antibodies which are considered to be able to differentiate epithelial and myoepithelial cells in the breast have been developed. Human mammary carcinoma cell line (HBC-4W) was used for immunization. Monoclonal antibodies-B4B2F10 (epi-1), E9E8B7 (myo-1)-with IgM was examined using tissues from diseased breast by avidin-biotin-peroxidase assay. Epi-1 antibody reacted with epithelial cells while myo-1 antibody reacted with myoepithelial cells in the mammary glands, respectively. The reaction was markedly visible, in particular, in fibroadenoma, mastopathy, and papilloma, which showed clear two-cell-type structures. In the infiltrating ductal carcinoma, epi-1 antibody reacted with carcinoma cells, while myo-1 antibody reacted with stromal cells rather than carcinoma cells suggesting that infiltrating ductal carcinoma was mainly of epithelial origin. In the infiltrating lobular carcinoma, however, myo-1 as well as epi-1 antibodies reacted with carcinoma cells. It is suggested that infiltrating lobular carcinoma was of a mixture of epithelial and myoepithelial cell origin.

A monoclonal antibody CIBr17 recognizes a myoepithelium-specific antigen in human mammary gland

A murine monoclonal antibody (MAb) CIBr17, raised against the human breast carcinoma cell line PMC42, reacts specifically with myoepithelial cells in normal human breast. This IgGl antibody recognizes a approximately 110kDa glycoprotein that is expressed on the cell surface and junctional membranes of PMC42 monolayer cultures. The CIBr17 antigen is present in two major glycosylated forms with approximate pls of 5.2 and 5.5 respectively in PMC42 cells. The tissue specificity of CIBr17 was assessed on frozen sections of PLP-fixed tissues by means of a 4-layer immunoperoxidase technique. CIBr17 has reacted with a variety of epithelium-derived tissues and some smooth muscle cells. Within many epithelial tissues, CIBr17 has demonstrated specific staining of particular epithelial cell types. Within normal breast and most benign breast lesions, antibody CIBr17 stained only myoepithelial cells. No staining of luminal epithelium, basement membranes or stromal elements was observed. In sclerosing adenosis, CIBr17 stained areas of pronounced myoepithelial differentiation, while in duct epitheliosis variable staining of proliferating cells was observed. In breast carcinomas, CIBr17 demonstrated variable antigen expression. In most tumors, CIBr17 either did not stain any tumor cells or stained only a small number of tumor cells spread randomly throughout the tumor. In several ductal carcinomas, however, CIBr17 stained the majority of tumor cells.

Feline mammary sarcoma composed of cells resembling myofibroblasts

A recurrent mammary sarcoma from an 11-year-old, female domestic cat was studied by light and electron microscopy and immunohistochemistry. The tumor consisted of interlacing bands of spindle cells with elongated blunt-ended nuclei and variable amounts of stroma. Multinucleated tumor giant cells and mitoses were common. Ultrastructurally, tumor cells had abundant rough endoplasmic reticulum with dilated cisternae, a prominent Golgi complex, frequent mitochondria, bundles of intracytoplasmic filaments with focal densities, and discontinuous basal lamina-like material and cell junctions. These findings suggest that myofibroblast-like cells were the predominant type of tumor cell. Failure to demonstrate immunoreactivity for cytokeratins attested to the non-epithelial origin of these neoplastic cells. Uniform immunoreactivity with anti-vimentin antibodies and specific labelling of some tumor cells with antiserum to actin are compatible with an origin of this tumor from modified fibroblasts (i.e., myofibroblast-like cells). Tumors composed largely of myofibroblasts may be unique and warrant separate classification from other types of fibroblastic tumors in animals.

Proliferation of Dunning R-3327 rat prostatic adenocarcinoma and of its sublines (CUA and CUB)

Proliferating cells in tumors of the androgen-dependent R-3327 and its partially dependent and autonomous sublines, CUA and CUB, were examined. Two types of cells, myoepithelial cells and large stromal cells, in the R-3327 have a high proliferating ability, as estimated by thymidine uptake. These cells were also observed in the normal dorsolateral prostate of rats, the lobes from which R-3327 originated. CUA is a squamous carcinoma, which proliferates at the border of the epithelial layer and large stromal cells. The tumor cells of CUB appear as clusters of large stromal cells which have a strong potential for dividing. Therefore, R-3327 contains two types of dividing cells, and their uncoordinated proliferation may be responsible for causing the different features seen in the sublines.

A monoclonal antibody that detects myoepithelial cells in exocrine glands, basal cells in other epithelia and basal and suprabasal cells in certain hyperplastic tissues

Myoepithelial and luminal cells of human exocrine glands can be positively identified with two different monoclonal antibodies. Myoepithelial cells including those of the salivary gland, mammary gland and sweat gland are positively identified by an antibody CKB1. This antibody does not stain luminal cells, but stains the basal cell layer of certain human stratified epithelia and a few basal cells in simple epithelia. Thus myoepithelial cells and basal cells have certain common features. Luminal cells can be positively stained with the CK5 monoclonal keratin antibody specific for keratin polypeptide 18; this antibody does not stain myoepithelial cells. Of interest is that CKB1 also appears to stain basal and suprabasal cells in certain hyperplastic conditions.

Monoclonal antibody that defines human myoepithelium

We have isolated a mouse monoclonal antibody that, upon immunohistochemical localization in frozen sections, displays specificity for human myoepithelial cells in the resting mammary gland, sweat glands, and salivary glands. Furthermore, this antibody was strongly and homogeneously reactive with frozen sections of 3 of 60 breast carcinoma specimens. Using immunolocalization techniques in conjunction with polyacrylamide gel electrophoresis, we have determined that the reactivity of this monoclonal antibody is directed toward a 51,000-dalton keratin polypeptide. The potential uses of this antibody in the prognosis of human mammary carcinoma and in understanding the role of the myoepithelium in development and differentiation are discussed.

Malignant myoepithelioma (myoepithelial carcinoma) of the breast: an ultrastructural and immunocytochemical study

This report describes the light (LM) and electron microscopic (EM) features and the results of an indirect immunofluorescence study (IF), the latter using monoclonal and monospecific antibodies to cytoskeletal proteins, of a malignant, invasive and metastatic breast myoepithelioma. A 53-year-old female underwent mastectomy for a large necrotic mammary tumor that had invaded the overlying skin. By LM, the neoplasm was composed of interlacing bundles of large, elongated and interspersed stellate cells with acidophilic cytoplasm. The neoplastic cells displayed a moderate degree of anaplasia, high mitotic activity, and strong tendency for necrosis. Stromal desmoplasia was marked, especially toward the center of the neoplasm. By IF, the tumor cells revealed bright cytoplasmic fluorescence with antibodies to actin, prekeratin, and cytokeratin. A few scattered spindle cells, which stained with the anti-vimentin and anti-actin anti-bodies, most likely represented stromal myofibroblasts. The anti-desmin reaction was negative. By EM, the neoplasm was composed of variably differentiated, elongated and stellate myoepithelial cells connected by desmosomes, enveloped by remnants of basal lamina, and containing pinocytotic vesicles, a well-developed rough endoplasmic reticulum, large Golgi areas, aggregates of intermediate filaments that were often arranged in dense curvilinear bundles (tonofilaments), and bundles of microfilaments with fusiform, dense bodies. The combined LM, EM, and IF study of this mammary tumor establishes its myoepithelial origin and, thus, identifies it as myoepithelial carcinoma distinct from other spindle cell breast tumors. This neoplasms was locally invasive and cytologically malignant; moreover, its malignancy was further confirmed by the development of lung and pleural metastases.

Findings of myoepithelial cells in human breast cancer. Ultrastructural and immunohistochemical study by means of anti-myosin antibody

Detailed light and electron microscopic, and immunohistochemical observations were made on the distribution and morphological characteristics of myoepithelial cells in the 53 cases of breast cancer. In non-invasive carcinoma, myoepithelial cells in the normal duct were found to be remaining at the outer margin of the cancer nests, but neoplastic myoepithelial cells were not detected in the carcinoma tissue. In invasive carcinoma, a small number of fluorescence-weakly-positive cells could be observed in more than 50% of medullary-tubular carcinoma, in all cases of papillary-tubular carcinoma, and two of three cases of invasive lobular carcinoma. Almost all of these cells were ultrastructurally intermediate cells which have the morphological characteristics of both epithelial cell and myoepithelial cell. Fluorescence-positive cells were observed in all cases of scirrhous carcinoma. Moreover, these cells showed a stronger fluorescence than that of other types of carcinoma and were ultrastructurally more similar to normal myoepithelial cell. The tumor cells having myoepithelial characteristics in invasive carcinoma showed a stronger tendency for arranging at the margin of carcinoma nests in contact with the stroma. The results of the present study indicate that in invasive carcinoma of the breast, neoplastic myoepithelial cells could be demonstrated together with ductal epithelial cells and as to its histogenesis, there is a possibility that breast cancer develops from common stem cells which have the ability of differentiating into both epithelial and myoepithelial cell because of the presence of intermediate cells.

Fine structure of cystosarcoma phyllodes with reference to smooth muscle tumors

The fine structure of the stomal component of cystosarcoma phyllodes was compared with that of intracanalicular fibroademona, leiomyoma and leiomyosarcoma. The stromal cells of fibroadenoma was intermediate between fibroblasts and smooth muscle cells and may be designated as myofibroblasts. The stromal cells of cystosarcoma phyllodes have fulfilled the ultrastructural criteria for smooth muscle cells. Therefore, cystosarcoma phyllodes should be regarded as smooth muscle tumors or those of myoepithelial origin.

Cytogenesis of murine mammary tumors in BALB/cfC3H and BALB/cfRIII strains

Biological and morphological differences in the mammary tumors of BALB/cfC3H and BALB/cfRIII mice are due to differences in the causative viruses. The C3H and RIII variants of the murine mammary tumor virus (MuMTV) might give origin to different mammary tumors by transforming different types of cell, i.e. epithelial or myoepithelial cells. The nature (epithelial or myoepithelial) of the neoplastic cells has been investigated by demonstrating their plasma membrane ATPase activities. We found that in normal murine mammary gland both epithelium and myoepithelium have Mg++ dependent ATPase activity, while the myoepithelium shows in addition an Na+K+ dependent ATPase activity. It is suggested that the results obtained exclude the participation of myoepithelium to the neoplastic growth and we ascribe the differences in mammary tumors of the two strains of mice to differences in the mechanisms of action of the virus variants.

Immunohistochemical studies on myoepithelial changes in breast tumors

Specific rabbit antisera directed against human uterine myosin were prepared and used for immunohistochemical studies on myoepithelial cells (MECs) in some breast tumors. In fibroadenomas, MECs were observed confined to the periductal portions but not in the stroma. In infiltrating duct carcinomas, MECs were also present as a distinctive periductal layer. Moreover, they were also seen in the infiltrating area, either associated with a small nest of carcinoma cells or freely in the stroma. Larger nests of medullary carcinomas usually were not accompanied by any layer of MECs. No MECs were detected in lobular carcinomas as far as the infiltrating area was concerned. It is suggested from these results that the behavior of MECs is significantly different, depending upon the types of breast tumors. It also appears that the present method may be useful for further analysis of the origin and growth pattern in various breast tumors.

Actin-rich (myoepithelial) cells in ductal carcinoma-in-situ of the breast

The distribution of the myoepithelial cells in 32 cases of ductal carcinoma-in-situ (DCIS) of the breast (11 not associated, 21 associated with invasive carcinoma) was investigated with a recently developed immunoperoxidase method for actin. Actin-rich myoepithelial cells were detected at the periphery of some ducts, however, their presence was neither constant nor continuous. Large areas of DCIS were devoid of a myoepithelial cell layer and the neoplastic cells were directly in contact with the stroma. No differences related to the histological pattern of DCIS or the presence and absence of invasive carcinoma were noted. The behaviour of the myoepithelial cells in ductal carcinoma appears different from that observed in cases of lobular carcinoma (Bussolati 1980) and of cystic disease, and may thus be of diagnostic interest. The selective destruction of myoepithelial cells in cases of DCIS might result in a focal disruption of the basement membrane, thus faciliatating invasion.

Acid mucopolysaccharides in mammary tumors of dogs

The predominant acid mucopolysaccharides found in selected epithelial mammary tumors of dogs stained with alcian blue and were labile to hyaluronidase digestion. These histochemical characteristics identified them as hyaluronic acid, chondroitin-4- and chondroitin-6-sulfate. The intensity of the staining of these acid mucopolysaccharides varied in a transitionary process from a precartilaginous to a pseudocartilaginous intercellular matrix to mature hyaline cartilage. The tumor acid mucopolysaccharides were indistinguishable from those associated with formation of cartilage in developing mammals; such cartilage is reported to be produced only by cells of mesodermal origin. There was no evidence to suggest transitional changes in myoepithelial cells, neoplastic epithelial cells or their components that could contribute to the formation of the acid mucopolysaccharides. It was concluded that the heterotopic tissues (cartilage, bone and fibrous connective tissue) in the epithelial mammary tumors were derived from cells of mesodermal origin and formed the adjacent stroma in areas of neoplasia.

Histochemical patterns in human breast tumours

Histochemical investigations carried out on 104 breast tumours (10 benign proliferations and 94 carcinomas) showed that breast carcinomas were characterized by various enzymological equipments in relation to tumour differentiation degree, histogenesis, functional stage, site of tumour cells in the carcinomatous islands or cords and to hormonal factors. Tumour cells -- stroma interrelationships study pointed out that high glycolysis (high LDH, NADPH2-TR, NADH2-TR activities) and an intense LEPA-activity of tumour cells seem to be favourable for proliferation and local tumour cells migration.

ATPase activity in the breast: a comparison between three methods

Adenosine triphosphatase enzymatic activity was investigated in human approximatively normal, dysplastic and neoplastic mammary tissue, by three different methods. Staining intensity varied within wide limits; myoepithelial cells and blood vessels showed similar enzymatic activity. Epithelial cells reacted only faintly, or not at all; carcinoma cells were never labelled. Stromal response was highly variable. The calcium-cobalt method of Padykula and Herman gave more intense reactions than the lead-nitrate procedure of Wachstein and Meisel, either in the original form or according to the modifications recommended by Russo and Wells. With the latter method the sharpness of stain deposits on the different structures was markedly enhanced. The functional significance of ATPase activity is discussed.

The ultrastructure of tubular carcinoma of the breast

The ultrastructure of four tubular carcinomas of the breast is described. The neoplastic tubules are single layered and lack a myo-epithelial component, an important feature in distinguishing tubular carcinoma from sclerosing adenosis. Numerous myo-fibroblasts are present in the stroma of all four tumours and, since cells of this type have been recorded only occasionally in the stroma of other types of breast carcinoma, it is suggested that they may be a characteristic feature of tubular carcinomas.

[The ultrastructure of mixed mammary gland tumors in bitches. IV. The incidence of myoepithelial cells in formation of spindle cells (author's transl)]

Spindle cells of myomatous formations of 19 canine mixed mammary tumors were studied by light and electron microscopy. The EM findings indicate that the spindle-shaped tumor cells are mostly of myoepithelial origin. However there were also formations of spindle cells which consisted of fibroblasts or fibrocytes. By light microscopy they are not always clearly distinguishable.

Distribution of adenosine triphosphatase in infiltrating ductal carcinoma and non-neoplastic breast

The histochemical reaction for adenosine triphosphatase (ATPase) has previously been used to differentiate myoepithelial from epithelial cells in the breast and to investigate the possible contribution of myoepithelial cells to mammary carcinoma. Discrepancies in published reports prompted this study of ATPase in non-neoplastic breast and infiltrating ductal carcinoma. ATPase was localized mainly on myoepithelial cells of normal breast and was identified with significant frequency on epithelial cells in hyperplastic ducts. Infiltrating ductal carcinomas usually displayed a variable reactivity. In one instance, malignant cells demonstrating mucin production were found to be ATPase-positive. An infiltrating ductal carcinoma of the papillary type with apocrine features was also strongly ATPase-reactive. It is concluded that ATPase is not an exclusive marker of myoepithelial cells and, therefore, data resulting from the use of this enzyme to study the role of the myoepithelium in mammary carcinoma must be interpreted with caution.

Calcification in human breast carcinomas: ultrastructural observations

Calcification in human breast carcinomas has been studied ultrastructurally. Multiple deposits of needle-shaped crystals intimately associated with electrondense material were observed among tumour cells. Similar deposits were present in intracytoplasmic lumina and the adjacent stroma. Cytoplasmic calcification was seen in membrane-bound vesicles and as partially membrane-bound clusters of crystals. It is suggested that the calcification is the result of an active secretory process rather than calcified necrotic or degenerate tumour cells. The possible mechanisms of calcification are discussed. Both electron diffraction and electron probe analysis show that the crystaline material is hydroxyapatite.

A cytochemical study on the salivary gland pleomorphic adenoma (mixed tumor) and the fetal and adult salivary gland

We studied the pleomorphic adenoma of the salivary gland ultrastructurally and cytochemically [Mg2+-activated adenosine triphosphatase (Mg2+-ATPase)], compared it with normal human fetal and adult salivary glands, and evaluated the histogenesis of this tumor. In the adult salivary gland, reaction products shows Mg2+-ATPase activity were localized in the plasma membranes of myoepithelial cells adjacent to the acinar cells or intercalated duct cells. However, in the salivary gland of the 16-week fetus, they were seen along all adjoining plasma membranes of the cells of terminal buds and duct-like structures. The present case of pleomorphic adenoma comprised two histological components: solid and myxomatous areas. Reaction products were seen along adjoining plasma membranes of both light and dark cells in solid areas.