Clear cell myoepithelial neoplasm of the breast

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.

Extensive extranodal metastases of basal-like breast cancer with predominant myoepithelial spindle cell differentiation

A differentiation towards myoepithelial cells has been demonstrated in several types of lesions in the breast. These include multifocal myoepitheliomatosis, the rare mixed tumor or pleomorphic adenoma, adenoid cystic carcinoma, adenomyoepithelioma and myoepithelial carcinoma (malignant myoepithelioma). Myoepithelial carcinoma is the only lesion purely composed of myoepithelial cells. All these tumors are benign and/or of low-grade malignancy, with the exception of malignant myoepithelioma. In contrast to the statement of the current World Health Organization (WHO), recent studies have reported that regional and distant metastases may occur in about 50% of pure myoepithelial carcinomas. The presented case of a breast carcinoma with dominant myoepithelial/spindle cell differentiation in a 58-year-old woman is an excellent example to document the highly aggressive biological behavior of this tumor phenotype. Despite an extensive chemotherapy and radiotherapy, the tumor was rapidly progressive, forming a finally exulcerating local tumor relapse and widespread metastases to the myocardium, lungs, liver, kidneys and skin. Similarities in morphology and biological behavior compared to patients with "triple-negative" (hormone receptor and Her2) monophasic sarcomatoid carcinomas and pure spindle cell sarcomas are discussed.

Salivary gland-type tumors of the breast: a spectrum of benign and malignant tumors including "triple negative carcinomas" of low malignant potential

Salivary gland-type neoplasms of the breast are uncommon and comprise numerous entities analogous to that more commonly seen in salivary glands. The clinicopathologic spectrum ranges from benign to malignant but there are important differences as compared with those of their salivary counterpart. In the breast, benign adenomyoepithelioma is recognized in addition to malignant one, whereas in the salivary gland a histologically similar tumor is designated as epithelial-myoepithelial carcinoma without a separate benign subgroup. Mammary adenoid cystic carcinoma is a low-grade neoplasm compared with its salivary equivalent. It is also important to appreciate that in contrast to "triple negative" conventional breast carcinomas with aggressive course, most salivary-type malignant breast neoplasms behave in a low-grade manner. Most of these tumors are capable of differentiating along both epithelial and myoepithelial lines, but the amount of each lineage-component varies from case to case, contributing to diagnostic difficulties. Well established examples of this group include pleomorphic adenoma, adenomyoepithelioma, and adenoid cystic carcinoma. Another family of salivary gland-type mammary epithelial neoplasms is devoid of myoepithelial cells. Key examples include mucoepidermoid carcinoma and acinic cell carcinoma. The number of cases of salivary gland-type mammary neoplasms in the published data is constantly increasing but some of the rarest subtypes like polymorphous low-grade adenocarcinoma and oncocytic carcinoma are "struggling" to become clinically relevant entities in line with those occurring more frequently in salivary glands.

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.

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.

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.

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.

The role of fine-needle aspiration cytology in the evaluation of metastatic clear cell tumors

BACKGROUND

Clear cell tumors (CCTs) occur as primary neoplasms in a number of anatomic sites. Due to their overlapping morphologic features, these tumors can be challenging for the cytologist, particularly when they present as metastatic lesions.

METHODS

Forty-nine fine-needle aspirations (FNA) of metastatic CCTs from 46 patients (age range, 29-87 years; mean, 64 years) were reviewed retrospectively. In addition to the routine smears and cell block preparations, ancillary studies were performed in selected cases. Clinical and/or histologic follow-up was obtained for all patients.

RESULTS

The sites of the 49 FNAs were the lung (12 cases), lymph nodes (9 cases), liver (7 cases), bone (7 cases), soft tissue (4 cases), pelvis (2 cases), adrenal gland (2 cases), pancreas (1 case), thyroid (2 cases), peritoneum (2 cases), and vagina (1 case). Twenty-seven patients had a previous history of a CCT and the FNA material in these cases was consistent with a metastasis. The primary anatomic sites in these cases were the kidney (20 cases), ovary (2 cases), salivary gland (1 case), and cervix (1 case). On light microscopy, these tumors had a similar appearance and often were indistinguishable. Nineteen patients did not have a prior history of malignancy; 12 of these patients had a concurrent renal mass and the diagnosis of metastatic renal cell carcinoma was made. The anatomic site of origin of seven of the ten remaining tumors (kidney [2 cases], lung [2 cases], ovary [1 case], germ cell [1 case], and endometrium [1 case]) was established through immunocytochemical studies of cytologic material and clinical follow-up.

CONCLUSIONS

FNA plays an important role in the diagnosis of metastatic CCT. Cytologic examination, ancillary studies, and clinical information can establish the anatomic site of origin in the majority (95%) of cases, precluding the necessity of obtaining additional tissue. Cancer (Cancer Cytopathol)

Clear cell mammary malignant myoepithelioma with abundant glycogens

Malignant myoepithelioma (myoepithelial carcinoma) of the breast is extremely rare. A case is reported of a 46 year old female with clear cell mammary malignant myoepithelioma that, on histological examination, was glycogen abundant clear cell carcinoma. Immunohistochemically, the clear cells showed myoepithelial differentiation--that is, they were a smooth muscle actin and S100 protein positive. This case shows that glycogen abundant clear cell carcinoma is a variant of malignant myoepithelioma of the breast.

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.

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.

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.

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.

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.

Adenomyoepithelioma of the breast: fine-needle sampling with histologic, immunohistologic, and electron microscopic analysis

Fine-needle sampling was performed in a woman with a subareolar breast mass. The cytologic diagnosis was consistent with a benign sweat gland-type tumor. Cytologic features included epithelial cells and spindle-shaped cells lying free or in fibrillary myxoid ground substance. Histologic study revealed the biphasic appearance of this tumor composed of proliferating myoepithelial cells and glandular epithelial cells as supported by immunohistologic and electron microscopic analyses. Epithelial cells were strongly positive for cytokeratins, and spindle cells were positive for actin, S-100 protein, and keratin and showed ultrastructurally typical features of myoepithelial cells.

An epithelial and spindle cell breast tumour of myoepithelial origin. An immunohistochemical and ultrastructural study

An infiltrating epithelial and spindle cell neoplasm developed in the breast of a 63-year-old female. An excisional biopsy was performed. Recurrence with rapid growth due to cyst development eventually resulted in more radical surgery. Interim fine needle aspirations had established its partially cystic nature. The unique microscopic appearance prompted the application of immunohistochemistry and electron microscopy. The tumour cells were found to exhibit characteristics denoting squamous and myoepithelial differentiation. Histopathological features of malignancy were absent. Our findings demonstrate the differentiation potential of breast epithelium. They are in concordance with the results of previous studies which delineate the histochemical and ultrastructural features of myoepithelial and establish the relationship of these cells to squamous metaplasia.