Malignant myoepithelioma of the breast. An immunohistochemical study by light and electron microscopy

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.

Soft Tissue Myoepithelial Carcinoma of the Neck with Spinal Invasion

Soft tissue myoepithelial neoplasms are a rare yet diverse group of tumors, ranging from benign to malignant lesions. Their presentation in the head and neck region is uncommon and represents a challenging diagnosis. Early identification of myoepithelial carcinoma is crucial given its more aggressive course compared to its benign counterpart, although the histopathological distinction between the two can be difficult. EWSR1 gene rearrangement is found in half the cases and has a speculative role in pathogenesis. Complete excision remains the treatment of choice. The roles of chemotherapy and radiation are unclear. We report the hospital course of a 33-year-old female who presented to our institution with a posterior neck mass with spinal invasion, diagnosed as myoepithelial cancer. A literature review of these rare tumors is discussed here.

Malignant Myoepithelioma of the Breast Clinically and Histologically Masquerading as Angiosarcoma: Cytological Findings and Review of the Literature

BACKGROUND

Malignant myoepithelioma of the breast is an exceptionally rare, aggressive tumor with a diverse morphology, the cytological features of which have only occasionally been described.

CASE REPORT

Our case comprises a 74-year-old woman who was admitted to our hospital with an erythematous, inflammatory-like mass of her left breast with nipple ulceration, and clinically fixed to the chest wall. The woman underwent fine-needle aspiration and biopsy. The aspirates consisted mainly of loose aggregates of large, highly pleomorphic, polygonal epithelioid cells as well as aggregates of spindle cells with prominent, easily detectable mitoses and single, multinucleated pleomorphic giant cells. The cytological diagnosis was consistent with high-grade malignancy. Histologically, the lesion consisted broadly of eosinophilic epithelioid cells with globoid cytoplasm in a reticulated, angiomatoid pattern and of spindle (sarcomatoid) cells in a storiform pattern, highly suspicious of angiosarcoma. A final diagnosis of malignant myoepithelioma was made.

CONCLUSION

We present the cytological findings in comparison with the unusual histological features of a malignant myoepithelioma of the breast. A high degree of suspicion with a keen eye for morphological details coupled with relevant immunohistochemistry will aid in arriving at the correct diagnosis.

K5/K14-positive cells contribute to salivary gland-like breast tumors with myoepithelial differentiation

Salivary gland-like tumors of the breast show a great variety of architectural patterns and cellular differentiations such as glandular, myoepithelial, squamous, and even mesenchymal phenotypes. However, currently little is known about the evolution and cellular differentiation of these tumors. For that reason, we performed an in situ triple immunofluorescence lineage/differentiation tracing (isTILT) and qRT-PCR study of basal (K5/K14), glandular (K7/K8/18), and epidermal-specific squamous (K10) keratins, p63, and smooth muscle actin (SMA; myoepithelial marker) with the aim to construct and trace different cell lineages and define their cellular hierarchy in tumors with myoepithelial differentiation. isTILT analysis of a series of 28 breast, salivary, and lacrimal gland tumors, including pleomorphic adenomas (n=8), epithelial-myoepithelial tumors (n=9), and adenoid cystic carcinomas (n=11) revealed that all tumor types contained K5/K14-positive progenitor cells in varying frequencies from a few percent up to 15%. These K5/K14-positive tumor cells were found to differentiate to glandular- (K8/18-positive) and myoepithelial-lineage (SMA-positive)-specific cells and were also shown to generate various heterologeous cell differentiations such as squamous and mesenchymal progenies. p63 was co-expressed with K5/K14 in basal-like progenitor cells, myoepithelial, and squamous cells but not in glandular cells. Our results show that the corresponding counterpart tumors of breast and salivary/lacrimal glands have identical cellular compositions. Taken together, our isTILT and RNA-expression data indicate that look-alike tumors of the breast represent a special subgroup of basal-type tumors with benign or usually low malignant potential.

Cutaneous myoepithelioma in the foot: case report

Cutaneous myoepithelioma is a very rare, benign, subcutaneous and dermal tumor. It usually presents as a slow-growing and painless mass on the extremities. We report a case of cutaneous myoepithelioma that was located on the foot. A 68-year old woman presented with a slowly growing pain-free mass on the right third toe measuring 0.8 × 0.7 × 0.4 cm(3). We performed an elliptical excision, with histological and immunohistochemical analysis. The lesion showed dermis with cords of cytologically uniform ovoid cells with moderate amount of pale cytoplasm. No pleomorphism, mitotic activity, or necrosis was visualized. The tumor cells were positive for S-100 protein, epithelial membrane antigen and negative for smooth-muscle actin. From these findings, the tumor was diagnosed as a cutaneous myoepithelioma extending to the deep resection margin. To our knowledge, there are only 2 documented cases in the literature in English, and none have been reported in the foot and ankle literature.

[Malignant myoepithelial breast carcinoma: diagnosis and therapeutic difficulties]

Myoepithelial carcinoma of the breast is a rare and malignant tumor. Local recurrence and distant metastasis are common. Treatment is not consensual. Here, we report a case of a 61-year-old female who developed a myoepithelial carcinoma. Primary treatment was a local wide excision with clear pathological margins. Three years later, a local recurrence was treated by further wide excision. Neither recurrences nor distant metastasis were detected four years later. Regular following of patients with myoepithelial carcinoma is essential.

Derivation of myoepithelial progenitor cells from bipotent mammary stem/progenitor cells

There is increasing evidence that breast and other cancers originate from and are maintained by a small fraction of stem/progenitor cells with self-renewal properties. Recent molecular profiling has identified six major subtypes of breast cancer: basal-like, ErbB2-overexpressing, normal breast epithelial-like, luminal A and B, and claudin-low subtypes. To help understand the relationship among mammary stem/progenitor cells and breast cancer subtypes, we have recently derived distinct hTERT-immortalized human mammary stem/progenitor cell lines: a K5(+)/K19(-) type, and a K5(+)/K19(+) type. Under specific culture conditions, bipotent K5(+)/K19(-) stem/progenitor cells differentiated into stable clonal populations that were K5(-)/K19(-) and exhibit self-renewal and unipotent myoepithelial differentiation potential in contrast to the parental K5(+)/K19(-) cells which are bipotent. These K5(-)/K19(-) cells function as myoepithelial progenitor cells and constitutively express markers of an epithelial to mesenchymal transition (EMT) and show high invasive and migratory abilities. In addition, these cells express a microarray signature of claudin-low breast cancers. The EMT characteristics of an un-transformed unipotent mammary myoepithelial progenitor cells together with claudin-low signature suggests that the claudin-low breast cancer subtype may arise from myoepithelial lineage committed progenitors. Availability of immortal MPCs should allow a more definitive analysis of their potential to give rise to claudin-low breast cancer subtype and facilitate biological and molecular/biochemical studies of this disease.

Malignant myoepithelioma of the breast

Malignant myoepithelioma of the breast is rare. A 50-year-old Japanese woman was admitted to our hospital because of a right breast tumor (11 × 10 × 5.5 cm). Core needle biopsy revealed malignant spindle cells. A mastectomy was performed. The tumor consisted of malignant spindle, round, pleomorphic and giant cells with many mitotic figures and necrotic areas. Tumor and osteoclast-like giant cells were scattered. Much lymphovascular permeation was seen. In a few areas, particularly on the tumor periphery, there were merges between the tumor cells and myoepithelial cells of the non-tumorous ducts, as if the tumor emanated from the duct myoepithelium. The tumor was invasive into the skin and pectoral muscle. Immunohistochemically, the tumor cells were diffusely positive for vimentin, CD10, α-smooth muscle antigen, and Ki-67 (labeling = 95%). The significant areas of the tumor were positive for S100 protein, p63, p53, CD68, caldesmon, desmin and TGFβ1. A few areas were positive for pancytokeratin (AE1/3), cytokeratin (CK) 5/6, and CK 34βE12. In contrast, the tumor cells were negative for pancytokeratins (WSS, CAM5.2), CK7, CK8, CK14, CK18, CK19, CK20, EMA, CEA, bcl-2, myoglobin, CD34, CD56, CD45, HMB45, GFAP, α-1-antitrypsin, synaptophysin, estrogen receptor, progesterone receptor, HER2/neu, MUC1, MUC2, MUC5AC and MUC6. The author diagnosed the tumor as malignant myoepithelioma, as myoepithelial markers (C10, p63, S100 protein, α-smooth muscle actin, caldesmon) were positive, and also because there was a transition between the tumor cells and myoepithelium of non-tumorous ducts. The grade of the tumor was high. The patient was treated with chemoradiation and was free of disease 5 months after the operation.

Malignant myoepithelial tumor of soft tissue: a report of two cases of the lower extremity and a review of the literature

Myoepithelial tumors of the soft tissues have only recently been described. Two cases of lower extremity malignant myoepithelial tumors are reported. One case of malignant mixed tumor overlying the gastrocnemius muscle was treated with wide local excision, but metastasized to regional lymph nodes 14 months after surgical excision. One patient with malignant myoepithelioma of the right lower leg was treated with limb amputation and is alive without disease at 46 months. A review of the literature discloses 120 additional cases of soft tissue myoepithelial tumors, 102 of which are myoepitheliomas and 18 are mixed tumors. Thirty-seven percent of the myoepitheliomas met the criteria for malignancy, and 33% of the mixed tumors were malignant. Of these, 30% had locally recurrent disease and 32% developed metastatic disease. Treatment benefit from chemotherapy and radiation therapy is unclear.

Focal degeneration of aged or injured myoepithelial cells and the resultant auto-immunoreactions are trigger factors for breast tumor invasion

The development of breast cancer is believed to be a multi-step process, sequentially progressing from normal to hyperplastic, to in situ, and to invasive stages. The progression from the in situ to invasive stage is believed to be triggered primarily, if not solely, by the overproduction of proteolytic enzymes by cancer cells, which cause degradation of the basement membrane. This theory is consistent with data derived from studies with cell cultures or animal models, while results from recent worldwide clinical trials with a variety of proteolytic enzyme inhibitors have been very disappointing, casting doubt on the validity of the enzyme theory. Based on our recent studies, we propose that breast tumor invasion is triggered by the following mechanisms and events: (1) the predisposition of genetic abnormalities in ME cell replenishment-related genes or other insults results in elevated focal degeneration of ME cells in some individuals; (2) the degradation products of ME cells or diffusible molecules of epithelial cells attract infiltration of immunoreactive cells (IRC) into the affected sites; (3) the direct physical contact between IRC and degenerated ME cells results in the discharge of digestive enzymes from IRC, causing focal disruptions in the ME cell layer; (4) focal disruptions in a given ME cell layer result in a localized loss of tumor suppressors and paracrine inhibitory function, a focal increase of permeability for oxygen, nutrients, and growth factors, and a localized increase of leukocyte infiltration, which facilitate the monoclonal proliferation of tumor progenitors, forming a biologically more aggressive cell cluster overlying the disrupted ME cell layer; (5) the direct physical contact between the newly formed cell cluster and stromal cells stimulates the production of tenascin and other invasion-associated molecules that facilitate tissue remodeling, angiogenesis, and epithelial-mesenchymal transition, providing a favorable micro-environment for proliferation and invasion. Our hypothesis differs from the enzyme theory in the stage of tumor invasion, the cellular origin of invasive lesions, the significance of IRC and stromal cells, and the potential approaches for treatment and prevention. If confirmed, our hypothesis could facilitate the early detection of specific individuals at increased risk to develop invasive breast cancer. More importantly, our hypothesis may facilitate development of novel approaches, including stimulating ME cell growth, neutralizing ME cell degradation products, manipulating the types and extent of IRC infiltration, and controlling the extent of stromal reactions, to combat tumor invasion.

Cytologic findings in malignant myoepithelioma: a case report and review of the literature

Background

Myoepithelioma of the breast is a rare tumor and the cytologic features have only been described in one previous report.

Case presentation

The present case comprises a 70 year old woman with a mammographic equivocal and ultrasonographic suspicious lesion. The aspirates were cellular and consisted mainly of single spindle or polymorphic, polygonal cells. The nuclei were generally large, ranging from 2 - > 5 × RBC. Most nuclei had a distinct medium-sized nucleolus. The nuclear outlines were irregular with buds and folds. The chromatin was granular. In the background there was abundant granular metachromatic ground substance and some metachromatic stromal fragments. A few mitotic figures were found. The cytologic diagnosis was suspicious for malignancy and a metaplastic carcinoma where only the non-epithelial component had been aspirated, or a non-epithelial lesion, was suggested.

Macroscopically the tumor was round, seemingly well circumscribed, firm and with a white cut surface. The lesion consisted of spindled and polygonal cells with distinct pleomorphism. There were 6–9 mitoses per high power field (HPF). The tumor infiltrated in the surrounding fatty tissue. On immunohistochemistry, tumor cells were positive for smooth muscle actin, keratin MNF 116 and vimentin. Desmin and S-100 were negative.

Ultrastructurally, there were abundant tonofilaments, including globular filamentous bodies and granulated endocytoplasmic reticulum with many dilated cisterns. The histologic diagnosis was malignant myoepithelioma.

Conclusion

The case mirrors completely the WHO definition and the previous cytological and histological descriptions of malignant myoepitheliomas in the literature which describe a spindle cell population with unequivocal nuclear atypia, metachromatic background substance and mitoses.

Metaplastic Sarcomatoid Carcinoma of the Breast With Absent or Minimal Overt Invasive Carcinomatous Component

Metaplastic carcinomas of the breast are a heterogeneous group of neoplasms ranging from tumors with a predominant component of overt carcinoma and focal mesenchymal differentiation to keratin-positive tumors with pure sarcomatoid morphology. We examined the clinicopathologic features of 22 patients previously diagnosed at M.D. Anderson Cancer Center with metaplastic carcinoma of the breast with pure or almost pure sarcomatoid morphology. Patients were included in the study if their tumors had sarcomatoid morphology and: 1) an invasive carcinomatous component identifiable on hematoxylin and eosin stains comprising less than 5% of the invasive tumor; or 2) associated ductal carcinoma in situ; or 3) immunohistochemical expression of keratin in the sarcomatoid areas. Patients with low-grade fibromatosis-like metaplastic tumors and those who received neoadjuvant chemotherapy were excluded. Axillary lymph node dissection or limited axillary node excision was performed in 17 patients, including 1 patient who had a sentinel lymph node biopsy. Lymph node involvement occurred in only 1 patient and consisted of a single 3.5-mm metastasis. Clinical follow-up was available for 21 patients and ranged from 4 months to 155 months (median follow-up, 35 months). Ten patients experienced local relapse, including 7 of 11 patients treated with breast-conserving surgery, and 9 developed distant metastases, most frequently to the lungs. These findings suggest that metaplastic sarcomatoid carcinomas that lack or have only a minimal overt invasive carcinomatous component have a biologic behavior similar to that of sarcomas. In addition to systemic treatment, early aggressive local therapy is recommended, as these patients have a high rate of local relapse.

Myoepithelial cells: pathology, cell separation and markers of myoepithelial differentiation

Until recently the myoepithelial cell has been studied relatively little in terms of its role in breast cancer. A number of malignancies showing myoepithelial differentiation have been reported in the literature, although they are still thought to be relatively rare and only limited studies are published. As a result of recent expression profiling experiments, one type of tumor with myoepithelial features, the so-called 'basal' breast cancer, has received a renewed interest, although it has been known to pathologists for more than two decades. These tumors, which express markers of both luminal and myoepithelial cells, are now being studied using antibodies against some new molecules that have emerged from studies of sorted normal luminal and myoepithelial cells. These immunohistochemical data, combined with genomic studies, may lead to better identification and management of patients with 'basal' tumors.

The significance of focal myoepithelial cell layer disruptions in human breast tumor invasion: a paradigm shift from the "protease-centered" hypothesis

Human breast epithelium and the stroma are separated by a layer of myoepithelial (ME) cells and basement membrane, whose disruption is a prerequisite for tumor invasion. The dissolution of the basement membrane is traditionally attributed primarily to an over-production of proteolytic enzymes by the tumor or the surrounding stromal cells. The results from matrix metalloproteinase inhibitor clinical trials, however, suggest that this "protease-centered" hypothesis is inadequate to completely reflect the molecular mechanisms of tumor invasion. The causes and signs of ME cell layer disruption are currently under-explored. Our studies revealed that a subset of pre- and micro-invasive tumors contained focal disruptions in the ME cell layers. These disruptions were associated with immunohistochemical and genetic alterations in the overlying tumor cells, including the loss of estrogen receptor expression, a higher frequency of loss of heterozygosity, and a higher expression of cell cycle, angiogenesis, and invasion-related genes. Focal ME layer disruptions were also associated with a higher rate of epithelial proliferation and leukocyte infiltration. We propose the novel hypothesis that a localized death of ME cells and immunoreactions that accompany an external environmental insult or internal genetic alterations are triggering factors for ME layer disruptions, basement membrane degradation, and subsequent tumor progression and invasion.

Glycogen-rich clear cell mammary malignant myoepithelioma

Primary clear cell tumors of the breast are uncommon and often present a diagnostic challenge. We describe an extremely rare case of glycogen-rich clear cell malignant myoepithelioma in a 43-year-old woman. Histologically, this tumor is composed of clear cells with abundant cytoplasmic glycogen particles. Immunohistochemically, these tumor cells show co-expression of vimentin, smooth muscle actin, epithelial membrane antigen, S-100 protein, and cytokeratin as evidence of myoepithelial cell tumor. The pathological staging of the patient is IIB (pT3N0M0) and the nuclear grading is 2. The patient demonstrated no evidence of recurrence or metastasis over a period of 42 months. We suggest that glycogen-rich clear cell malignant myoepithelioma be included in the histological differential diagnosis of clear cell tumors of the breast.

Metastatic myoepithelioma of the breast

Myoepitheliomas are typically benign tumours arising from exocrine glands. There have only been five reports of malignant myoepitheliomas from breast origin previously published in the English literature. This report describes a patient with myoepithelioma arising in the breast which later metastasized despite the primary tumour having benign histological features. Impaired immune function due to end-stage renal failure and haemodialysis may have contributed to the malignant potential of her tumour. The literature regarding myoepithelial tumours is reviewed. All breast myoepitheliomas should be managed as potentially malignant tumours with appropriate surgical clearance and staging.

Myoepithelial markers are expressed in at least 29% of oestrogen receptor negative invasive breast carcinoma

Around 20% of invasive breast carcinoma are oestrogen receptor alpha (ER) negative. Theoretically, this negativity could be either due to the result of downregulation of ER expression in the tumour cells, or the result of the tumour being derived from or differentiating towards cells which normally lack that expression. Normal basal, including myoepithelial, cells of the breast are ERnegative. CD10, smooth muscle actin and S100 are markers of these basal cells that can be used for their demonstration in routinely processed sections. This study was aimed at comparing the incidence of positivity for three myoepithelial markers in ER-negative and ER-positive invasive breast carcinoma. We have examined sections of 117 cases of breast carcinoma, including 77 ER-negative and 40 ER-positive cases, for the expression of CD10, smooth muscle actin and S100, using the avidin-biotin complex immunoperoxidase technique. A tumour was considered positive if more than 10% of the tumour cells were positively stained. In all, 36 (47%) ER-negative tumours were positive for one or more of these myoepithelial markers. The percentage of positively stained tumour cells varied between 30 and 100%. Of the 40 ER-positive tumours, only three (8%) were positive; two for S100 and one for actin, with none being positive for CD10. If cases stained only with S100 are excluded, as some of these may represent luminal differentiation, definite myoepithelial differentiation seems to be present in 29% (22/77) of ER-negative tumours as compared with 2.5% (1/40) of ER-positive tumours; a difference which is highly significant (P<0.001). It is suggested that at least 29% of ER-negative invasive breast carcinomas may be derived from or differentiating along the direction of basal nonconventional luminal epithelial breast cells that normally lack the expression of ER but totally or partially express various myoepithelial markers. Such tumours might need a different therapeutic approach.

Clinical presentation and long-term outcome of pure myoepithelial carcinoma of the breast

INTRODUCTION

Pure myoepithelial carcinoma of the breast is a rare tumour of controversial histogenesis. Little is known about its natural history and long-term outcome following treatment.

METHODS

All patients with pure myoepithelial carcinoma treated at our institution between 1970 and 2001 were studied with respect to pathological features, outcome and prognosis.

RESULTS

Six patients were identified. The median age was 60 (40-66) years and median follow-up was 34.5 months (range 14-76) months. Four tumours were T1 and one was T2 (one tumour size unknown). There were two moderately differentiated and three well-differentiated tumours (grade could not be assessed in one patient). Oestrogen and progesterone receptor could be assessed in five patients and all were negative. Primary treatment was wide local excision with clear radial margins. Lymph node assessment was negative in all patients. One patient received adjuvant radiotherapy. Three patients developed local recurrence at 15, 38 and 50 months and two patients developed distant metastasis at 30 and 79 months. The local recurrences were treated by further excision but two patients developed distant metastasis at intervals of 15 and 26 months, respectively. Two patients have died of the disease and four remain well. The 2-year and 5-year survival was 88% (SE, 6) and 55% (SE, 16), respectively. Large tumour size is a prognostic indicator of poor outcome.

CONCLUSION

Pure myoepithelial carcinoma of the breast adopts an aggressive clinical course with an outcome comparable to poorly differentiated adenocarcinoma of the breast.

[Breast myoepithelioma. Diagnostic and therapeutic difficulties. A case report]

Breast myoepithelioma is rare. The case of a 61-year-old female is reported here. The tumor was clinically, radiologically and macroscopically demarcated. Diagnosis was based on histological and immunohistochemical studies. At the time of diagnosis the tumor consisted of myoepithelial cells with few cellular atypias and a low mitotic activity. Tumor cells expressed vimentin, actin, S100 protein and cytokeratin. No local or distant metastases were found. The patient had been treated initially with a large excision of tumor. Local recurrences detected one year after initial surgery and showed a similar morphology and immunoreactivity with higher mitotic activity. Mastectomy with axillary dissection was performed. Neither recurrences nor distant metastases detected two years later. Myoepithelial tumors which are generally considered as benign or low-grade lesions can give rise to a wide range of clinical evolution.

Myoepithelioma of the soft tissue of the head and neck: a case report and review of the literature

BACKGROUND

Extraglandular myoepitheliomas are neoplasms that seldom occur in the soft tissue of the head and neck region. Misdiagnosis of these neoplasms as more aggressive tumors can lead to unnecessary treatment.

METHODS

We describe a myoepithelioma of cervical soft tissue. The histopathology of the tumor, its immunophenotype, its differential diagnosis, and a review of the literature are presented.

RESULTS

Histopathologically, the tumor was composed of epithelioid cells with eosinophilic cytoplasm and eccentric nuclei arranged in cords and files. On immunohistochemical analysis, the cells expressed cytokeratin 14, calponin, glial fibrillary acid protein, and p63 and showed focal positivity for S-100 protein. Together, these markers identified the cells as myoepithelial type. A literature review identified only five cases of myoepithelioma in the soft tissue of the head and neck region in which detailed clinical information was provided.

CONCLUSIONS

Myoepitheliomas can have cells with variable morphology arranged in different histologic patterns. Immunohistochemical analysis is crucial for unequivocal diagnosis when myoepitheliomas occur in extraglandular locations.

An immunohistochemical study of metaplastic spindle cell carcinoma, phyllodes tumor and fibromatosis of the breast

The diagnosis of metaplastic (sarcomatoid) carcinoma (MSC) of breast often requires immunohistochemistry with a cytokeratin (CK) panel to distinguish them from phyllodes tumors (PT), primary sarcomas, and fibromatoses. CK staining may be heterogeneous in metaplastic carcinomas. The aim of the study was to investigate the theory that MSCs show evidence of myoepithelial differentiation and to evaluate immunohistochemical markers that may be helpful in distinguishing MSCs from PT and fibromatosis. We reviewed histology and performed immunohistochemistry for AE1/AE3, 34betaE12, CK5 and CK14, Cam5.2, CK7 and CK19, epithelial membrane antigen (EMA) (B55), smooth muscle actin (SMA), S100, desmin, vimentin, CD31, CD34, and bcl-2 on paraffin-embedded tissue from 18 MSCs, 26 PTs, and 8 fibromatoses. We assessed staining by using a semiquantitative method. Sarcomatous areas in MSCs were positive for 34betaE12 in 11 cases; for SMA in 10; for CK5 in 7; for CK14 in 6; for Cam5.2, AE1/AE3, and S100 in 5; and for CK7 and CK19 in 3. No CK expression was seen in stromal areas in PT or in fibromatoses. CD34 and bcl-2 were more frequently expressed in spindle cell areas in PTs (18 and 12 of 26, respectively) than in MSCs (0 and 2 of 18, respectively). MSCs show strong evidence of myoepithelial differentiation. CD34 and, to a lesser extent, bcl-2 positivity in PTs may be helpful in differentiating these two lesions from MSCs, particularly in small biopsies, because CK staining in MSCs may be heterogeneous. In our hands, 34betaE12 was the CK most frequently expressed in sarcomatoid areas in MSCs.

Salivary-type neoplasms of the breast and lung

Salivary-type tumors occur in multiple sites in the human body, likely related to a basic structural homology between exocrine glands in these different anatomic areas. This paper reviews these salivary gland tumor types in breast tissue and lung. Salivary-type tumors of both breast and lung are relatively uncommon in comparison to their salivary gland counterparts. This may be attributable in part to lack of familiarity with these tumors in extra-salivary sites, and in part to histologic overlap with other primary and metastatic tumor types. Recognition of these entities is improving as the clinical and pathologic features are better delineated, and tumors are more accurately classified. Prediction of malignant behavior is not always possible in these unusual sites. In some instances, such as adenoid cystic carcinoma, behavior is known to differ considerably from that of analogous primary salivary gland tumors and in other instances there are simply too few reported cases to allow for adequate prognostication. In fact, more recent papers discuss the need to consider a spectrum encompassing benign and malignant lesions, in both breast and lung. Of course, some entities show clear-cut evidence of malignancy with documented potential for metastasis, others show bland features and well-reported benign behavior, and the less well-defined entities reside between these two extremes. The molecular pathology of salivary gland tumors has been reasonably well investigated in that location; however; there are few molecular studies devoted to salivary-type tumors of the breast and lung. This represents a potential area for future growth in further clarifying these tumors and their behavior.

Salivary gland-like tumours of the breast: surgical and molecular pathology

Breast glands and salivary glands are tubulo-acinar exocrine glands that can manifest as tumours with similar morphological features, but that differ in incidence and clinical behaviour depending on whether they are primary in breast or salivary glands. Salivary gland-like tumours of the breast are of two types: tumours with myoepithelial differentiation and those devoid of myoepithelial differentiation. The first and more numerous group comprises a spectrum of lesions ranging from "bona fide" benign (such as benign myoepithelioma and pleomorphic adenoma), to low grade malignant (such as adenoid cystic carcinoma, low grade adenosquamous carcinoma, and adenomyoepithelioma), to high grade malignant lesions (malignant myoepithelioma). The second group comprises lesions that have only recently been recognised, such as acinic cell carcinoma, oncocytic carcinoma of the breast, and the rare mucoepidermoid carcinoma.

Multifocal, nascent, and invasive myoepithelial carcinoma (malignant myoepithelioma) of the breast: an immunohistochemical and ultrastructural study

This report describes the light microscopic (LM), immunohistochemical (IHC), and electron microscopic (EM) features of a multifocal, nascent, and invasive myoepithelial carcinoma of the breast. By LM, the spindle cells disclosed fibrillar acidophilic cytoplasm, mild nuclear atypia, and a low mitotic index. Myoepithelial differentiation was established through IHC (single- and double-labeling techniques) and EM: periductal and infiltrating spindle cells coexpressed total muscle actin, alpha-smooth muscle actin, vimentin, cytokeratin 14, and pankeratin, and their EM features were characteristic of myoepithelial cells, i.e., perinuclear tonofilaments, subplasmalemmal bundles of microfilaments with dense bodies, intermediate junctions, poorly developed desmosomes, pinocytic vesicles, and fragmented external lamina. No invasive epithelial cells disclosed luminal differentiation (by LM, IHC, EM), identifying, thus, this neoplasm as a pure spindle cell myoepithelial carcinoma of the breast.

Rare case of biphasic tumor of the breast with prominent CD34-positive spindle cells

We report an unusual case of biphasic tumor of the breast with prominent CD34-positive spindle cells. A 53-year-old woman presented with a mass in her right breast. Following an incisional biopsy, a partial mastectomy was done. Histologically, the tumor was a biphasic variant of a malignant spindle cell tumor of the breast. The lack of a leaf-like structure, together with the apparent myoid features of the spindle-shaped tumor cells, made it difficult to distinguish from malignant phyllodes tumor and from myoepithelial carcinoma. Immunohistochemistry revealed the spindle-shaped tumor cells to be myofibroblastic, but not myoepithelial in nature, ultimately categorizing this tumor as a malignant phyllodes tumor with prominent myofibroblastic differentiation.

CGH analysis of ductal carcinoma of the breast with basaloid/myoepithelial cell differentiation

2-18% of ductal carcinoma-No Special Type (NST) are reported to express basal cell keratin 14 and such tumours may have a different metastatic pattern and prognosis. We performed immunohistochemistry for cytokeratins 19 (luminal) and 14 (basal) on 92 ductal carcinoma-NST. Those tumours showing CK14 expression were further characterized by immunohistochemistry for myoepithelial cell phenotype and analysed by comparative genomic hybridization. The 7 cases of ductal carcinoma-NST exhibiting a basal cell phenotype were all grade III tumours and showed a molecular cytogenetic profile similar to more conventional myoepithelial cell carcinomas. Therefore it appears that grade III invasive ductal carcinomas contain a subset of tumours with specific morphological and cytogenetic characteristics, and probably prognosis for the patient.

The mammary myoepithelial cell--Cinderella or ugly sister?

The breast myoepithelial cell is the Cinderella of mammary biology. Although its contribution to benign and some malignant pathologies is recognised, it has been largely neglected in molecular and biological studies. The reason for this has been the perception that its role in normal physiology is confined to lactation and the belief that most breast cancers arise from luminal epithelial cells. This review presents our perspective on its broader biological significance and its potential use as a model system for understanding breast carcinogenesis.

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.

Malignant adenomyoepithelioma of the breast with malignant proliferation of epithelial and myoepithelial elements: a case report and review of the literature

Malignant adenomyoepithelioma of the breast is a rare lesion characterized by malignant proliferation of epithelial and myoepithelial cells that show characteristic histologic and immunohistochemical features. Eleven cases have been reported, 4 of which showed evidence of distant metastasis. The authors report a case of malignant adenomyoepithelioma in the axillary tail of a 71-year-old woman, one of the oldest patients described so far, and review the literature. Malignancy in the current case was evidenced by the presence of local invasion, high mitotic rate, and severe cytologic atypia. The tumor was associated with adenosis and lobular adenomyoepithelial hyperplasia. Malignant adenomyoepithelioma is a rare neoplasm, diagnosable by light microscopy and immunohistochemistry. To date, it has only been reported in women, who ranged in age from 26 to 76 years. Metastases have only been documented in tumors 2.0 cm in diameter or larger.

Spindle cell tumours of the breast: practical approach to diagnosis

Spindle cell tumours of the breast are uncommon and often present diagnostic challenges. The most important is the sarcomatoid/metaplastic carcinoma, which has monophasic and biphasic variants. Each of these groups presents special diagnostic difficulties. In the monophasic variant the mesenchymal component predominates and the epithelial element forms a minor component often detected only after immunohistochemical study. The spindle cell areas may be bland and therefore under-diagnosed as nodular fasciitis or fibromatosis. Alternatively they may be highly malignant with a pattern that is misinterpreted as primary sarcoma of the breast. In the biphasic variant, the difficulty is in distinguishing between sarcomatoid carcinoma, myoepithelial carcinoma or malignant phyllodes tumour. Other spindle cell lesions of the breast include the various myofibroblastic tumours, the spindle cell variant of adenomyoepithelioma, the varied primary breast sarcomas, metastatic tumours with spindle cell morphology and, finally, the very rare follicular dendritic cell tumour. A simple practical approach to the diagnosis of spindle cell lesions is presented to help the general surgical pathologist to compile a differential diagnosis and to arrive at the correct conclusion

Immunoreactivity of ductal cells with putative myoepithelial markers: A potential pitfall in breast carcinoma

The identification of an intact layer of myoepithelial cells (MECs) located between epithelial cells and the basal lamina is useful in differentiating benign breast lesions and carcinoma in situ from invasive breast carcinoma. In the present study we used three antibodies considered to be putative markers of MECs (S100 protein, muscle-specific actin [HHF-35], and smooth muscle actin [SMA]) in 100 formalin-fixed, paraffin-embedded histologic sections of breast in an attempt to compare their value in demonstrating MECs in benign breast tissue and breast carcinomas. We concluded that for identifying MECs in benign breast tissue, SMA appears to be the most reliable, followed closely by HHF-35, but S100 is very unreliable for this purpose. In breast carcinoma, all three stains showed variable cross-reactivity with myofibroblasts, being greatest with SMA. A significant number of tumor cells in ductal carcinoma, both intraductal and invasive, stain with these markers and this "cross-reactivity" is extremely high with HHF-35. Thus, immunohistochemistry should be interpreted cautiously in differentiating benign, in situ, and invasive breast neoplasms. The "cross-reactivity" also suggests the possibility of myoepithelial differentiation and/or high actin content of breast tumor cells.

Metaplastic breast carcinoma invading chest wall

Metaplastic breast carcinoma refers to a heterogeneous group of neoplasms in which the typical glandular growth pattern of the tumor undergoes metaplasia, either epithelial or stromal. A 59-year-old woman presented with a breast mass that recurred in 1 year and showed invasion of the chest wall. Histological sections of both the tumor and the recurrence showed a tumor composed predominantly of stromal spindle cells with neoplastic epithelial ducts. Squamous metaplasia was seen in some ducts. Immunohistochemical staining showed positive cytokeratin and epithelial membrane antigen staining of the epithelial cells. Smooth muscle actin, S100, and vimentin were diffusely positive in the stromal cells. Electron microscopy of the original lesion showed cells with squamous epithelial and smooth muscle characteristics, and other cells that formed lumens into which microvilli projected. Electron microscopy of the recurrent lesion showed primarily spindle-shaped cells with abundant tonofilaments in the perinuclear cytoplasm, desmosomes with associated tonofilaments, filaments with focal densities, often aligned parallel with the cell membranes, surface attachment plaques, and fragments of basement membrane. Pinocytotic vesicles were rare. These metaplastic cells are derived from myoepithelial cells which are multipotential and able to differentiate into epithelial or stromal cells.

Myoepithelioma of the retroperitoneum

An abdominal mass detected in a 36-year-old man was thought from radiologic studies to be a renal neoplasm, but at surgery the kidney was found to be uninvolved. The 9.5-cm retroperitoneal tumor was resected totally and found to be encapsulated, and it appeared to be benign by light microscopy. The pattern of the spindle cells throughout the tumor suggested a cellular schwannoma, but immunocytochemical and ultrastructural studies did not support schwannian differentiation and instead revealed epithelial and smooth muscle features compatible with a myoepithelioma.

Pleomorphic adenoma of the breast: case report and review of the literature

A tumor of the right breast was noticed in a 70 year old female. The tumor was round, 1 x 1 cm, and was encapsulated with thin fibrous tissue. The boundary was clear. The cut surface showed a mosaic pattern of brown and white dots and the texture was gritty. Histologically, glandular structures, trabecular or solid epithelial cell nests, myxoid, cartilaginous and osteoid areas, and one ossifying focus were found. Round, polyhedral or fusiform myoepithelial cells proliferated around the glandular structures and were dispersing into the myxoid and cartilaginous tissue. Myoepithelial proliferation was especially marked around the small glandular structure. Immunohistochemically, S-100 protein was strongly positive for the myoepithelial cells around the glandular structures and in the cartilaginous tissue. Until now, 54 cases of pleomorphic adenoma of the breast have been reported. In those cases, the subareolar region was a common site for the tumor, and pleomorphic adenoma was thought to arise from large ducts in this region. No Oriental patients have been reported in the literature.

Adenomyoepithelioma of the breast: fine-needle aspiration biopsy and histologic findings

Adenomyoepithelioma is an uncommon tumor of the breast which clinically presents as a discrete nodule and histologically is composed of lumenal spaces lined by a mixture of epithelial and myoepithelial cells. It has a spectrum of histologic appearances which are gradually gaining wider recognition. There are, however, only a few descriptions of the fine-needle aspiration biopsy (FNAB) findings in adenomyoepithelioma. We report the FNAB and histologic features of a mammary adenomyoepithelioma which contained a prominent epithelial component including a focus of marked epithelial atypia. This expands the spectrum of FNAB findings which have been reported in adenomyoepithelioma.

Malignant myoepithelioma (myoepithelial carcinoma) of the breast: a detailed cytokeratin study

AIMS

To study the expression of a range of cytokeratins by malignant myoepithelioma of the breast.

METHODS

Immunophenotyping was carried out using a panel of antibodies on paraffin wax embedded and frozen material using immunohistochemistry and double-labelled immunofluorescence. Electron microscopy was also performed.

RESULTS

The tumour cells were positive for CAM 5.2, actin, vimentin, and cytokeratin 14 and negative for cytokeratins 18 and 19. Electron microscopy showed well formed desmosomes and hemidesmosomes together with pinocytic vesicles, plentiful rough endoplasmic reticulum and 6 nM microfilaments with focal densities.

CONCLUSIONS

The pattern of cytokeratin expression provides further evidence that tumours with a specific myoepithelial phenotype occur rarely in the breast.

Intralobular growth of myoepithelial cell carcinoma of the breast

Two cases of intralobular carcinoma of the breast showing myoepithelial cell differentiation are reported. One was an in situ lesion localized within a fibroadenoma; the second was predominantly in situ, but areas of invasion were present. The neoplastic cells had round to ovoid nuclei and were polygonal to spindle in shape displaying glycogen rich clear cytoplasm. Alpha-smooth muscle actin was present in the cytoplasm of the neoplastic cells in both cases. In one case the same cells displayed cytoplasmic microfilaments at electron microscopic level. Intralobular growth of neoplastic myoepithelial cells has never been described in the literature, and this line of differentiation has to be added to the endocrine and apocrine features occasionally observed in in situ lobular carcinomas of the breast.

Myoepithelial carcinoma of the breast with distant metastasis and accompanied by adenomyoepitheliomas

A breast tumour in a 47-year-old female with axillary lymph node metastasis was interpreted as the rare malignant adenomyoepithelioma based on morphological and immunohistochemical studies. Multiple bone metastases developed and the patient died after 7 months. The malignant neoplasm consisted of cords and interlacing bundles of spindle cells with indistinct cell borders and clear cytoplasm. The cells stained positively for cytokeratin, S-100 protein, GFAP, and muscle-specific actin, and possessed basal lamina, pinocytic vesicles, tonofilaments, desmosomes, and intermediate filaments with dense bodies. In some areas, cells with microvillous projections enclosed small spaces. In the breast, foci of myoepithelioma with various morphological subtypes and infiltration coexisted, demonstrating the origin of the malignant tumour. The histogenesis of the myoepithelial tumours is discussed.

Breast solitary schwannoma: fine-needle aspiration biopsy and immunocytochemical analysis

A case of intramammary solitary schwannoma (SS) (benign neurilemoma) diagnosed by fine-needle aspiration biopsy (FNAB) and supported by immunocytochemical study is reported. The tumor arose in the right breast of an 18-yr-old woman and was clinically and radiologically considered a fibroadenoma. The smears obtained by FNAB of the lump showed clusters of spindle-shaped cells and suggested a benign mesenchymal neoplasm. The presence of some structures reminiscent of Verocay bodies and the immunocytochemical reactivity for S-100 protein antiserum demonstrated the schwannian nature of the tumor and suggested the diagnosis of SS. The final histologic examination confirmed the cytologic diagnosis.

Benign and malignant neoplasms of myoepithelial cells: cytologic findings

We report two myoepithelial cell neoplasms; a salivary gland tumor was malignant and a breast neoplasm was benign. Both were studied histologically, immunohistochemically, cytologically, and ultrastructurally. The malignant myoepithelioma recurred twice and metastasized to one regional lymph node. This tumor was infiltrative with areas of necrosis and hemorrhage. It was composed of malignant-appearing spindle and plasmacytoid cells. Both types of cells were immunoreactive to muscle specific actin, S-100 protein, cytokeratin, vimentin, and neuron-specific enolase. Ultrastructurally, features of myoepithelial cells were seen. Fine-needle aspirate smears showed spindle and plasmacytoid cells, numerous mitoses, and malignant-appearing nuclei. Spindle-cell adenomyoepithelioma of the breast, a small well-circumscribed firm nodule, featured multiple lobules of spindle cells associated with clear-cell glands at the lobular periphery. Histologically and cytologically, the lesion was cellular but appeared benign. The differential diagnosis of myoepithelial neoplasms is discussed.

Epithelioid leiomyoma of the breast with granular cell change: a case report

A 42-year-old woman with an epithelioid granular cell leiomyoma of the right breast is reported. The cells were spindle to polygonal and displayed finely granular cytoplasm. The smooth muscle differentiation of this tumor was shown by the immunohistochemical positivity of the neoplastic cells with anti-alpha smooth actin and antidesmin antisera. Microfilaments with focal densities were present in the cytoplasm at an ultrastructural level. The granular cytoplasmic changes are related to a relevant number of lysosomes within the neoplastic cells.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: benign mammary tumours and duct ectasias

Duct ectasias (n = 2) and different types of benign canine mammary tumours (n = 19) were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types (K), alpha-smooth muscle actin, vimentin, and desmin. In the duct ectasias and in most tumours the epithelial structures revealed an inner and outer cell layer. The inner cell layer was characterized by labelling with K 7, 8, 18, 19 and mostly also with K 4 and/or K 10 MoAbs. The outer cell layer was almost invariably labelled by K 14, K 14 and 17, and a-smooth muscle actin MoAbs. The labelling patterns of both duct ectasias and tumours corresponded largely to the patterns observed in normal mammary gland tissue, although a more distinct heterogeneity was seen. Tumours histomorphologically assumed to be of a myoepithelial origin did not show immunohistochemical features of myoepithelial cells. The myoepithelial nature of the vast majority of spindle-shaped cells present in the adenomas of the complex type and in the fibroadenomas of the benign mixed type could not be confirmed immunohistochemically. These cells, however, unequivocally expressed vimentin, suggesting proliferation of stromal cells in these tumours, which in the fibroadenomas of the benign mixed type may show metaplasia to bone or cartilage. In the duct ectasias and in some tumours, a fraction of elongated stromal cells, probably representing myofibroblasts, was labelled with the alpha-smooth muscle actin MoAb.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: malignant mammary tumours

Ten malignant canine mammary gland tumours and five metastases from three of these tumours were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against different human keratin types (K), alpha-smooth muscle actin, vimentin, and desmin. In all tumours the neoplastic epithelium was rather homogeneously labelled with the keratin MoAbs RCK 102 (K 5 and 8) and CAM 5.2 (K 8). The adenocarcinomas (n = 5), the solid carcinomas (n = 2), and the carcinosarcoma (n = 1) showed heterogeneous labelling with the MoAbs specific for luminal cell antigens in the normal canine mammary gland, i.e., K 18, K 7 and K 19 MoAbs. These cells were also immunoreactive with K 4 and K 10 MoAbs. The spindle cell carcinomas (n = 2), however, did not react with these MoAbs. All tumours except one adenocarcinoma were characterized by the absence of immunoreactive labelling with the alpha-smooth muscle actin MoAb. In the solid carcinomas this was associated with the absence of labelling with one or both basal cell specific keratin MoAbs, i.e., 8.7 (K 14 and 17) and RCK 107 (K 14), respectively. In contrast, the other malignant tumours showed marked labelling of neoplastic epithelium with these MoAbs. Another remarkable finding was the labelling of a limited to moderate number of neoplastic epithelial cells with the vimentin MoAb. The presence of such labelling patterns in canine mammary gland tumours may be indicative of malignancy. Metastatic tumour tissues had a labelling pattern largely similar to that of the primary tumour, although also loss of reactivity for some keratin MoAbs was seen.

Adenomyoepithelioma (myoepithelioma) of the breast in a male

Adenomyoepithelioma (myoepithelioma) of the breast in a 47-year-old man is reported. The tumor consisted of a prominent proliferation of spindle cells surrounding mammary ducts. Immunohistochemical and electron microscopic observations confirmed the myoepithelial origin of these spindle cells. This is the first report of an adenomyoepithelioma of the breast that developed in a male.