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

Malignant Adenomyoepithelial Tumour of the Breast - a Rare Diagnosis - Case Report

Breast adenomyoepithelioma is an unusual tumour characterized by a biphasic proliferation of epithelial and myoepithelial cells. Most of the breast adenomyoepitheliomas are considered to be benign and characterized by propensity for local recurrence. Malignant change can occur rarely in one or both cellular components. We here present a case of a 70-year-old previously healthy female who initially presented with a painless breast lump. The patient underwent wide local excision in view of suspicion of malignancy and sent for frozen section regarding the diagnosis and margins which surprisingly came as adenomyoepithelioma. Final histopathology came as low-grade malignant adenomyoepithelioma. The patient shows no sign of tumour recurrence in the follow up.

Breast lesions with myoepithelial phenotype

Myoepithelial cells (MECs) constitute a continuous layer of cells surrounding the breast glands, localised between the epithelial cells (ECs) and the basal membrane. MECs play important roles in normal mammary gland as they produce basal membrane and stimulate secretion. During neoplastic transformation, MECs act as a barrier preventing stromal invasion. MECs themselves can undergo a great variety of changes, ranging from hyperplastic to metaplastic, to neoplastic, and giving rise to a wide spectrum of morphological pictures sometimes difficult to interpret on routine diagnoses. Several benign and malignant breast tumours can present features of MECs differentiation. As these latter tumours are quite infrequent, the purpose of the present study is to offer a review of the morphological spectrum of MECs lesions, with correlations to prognosis.

Breast carcinomas of low malignant potential

Some breast carcinomas have a very low likelihood of metastasis to regional lymph nodes and distant sites and may be considered carcinomas of low malignant potential. In this article, we review the clinical, pathologic, immunophenotypic, and molecular features of selected breast carcinomas of low malignant potential including low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, encapsulated papillary carcinoma, solid papillary carcinoma, and tall cell carcinoma with reversed polarity.

Atypical breasts cancers

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Myoepithelial carcinomas comprise exclusively of tumour cells with myoepithelial differentiation and can be managed through surgical excision with radiotherapy.

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Mucinous carcinomas are difficult to diagnose but important to distinguish as survival rate between the types can vary.

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Invasive apocrine carcinomas are difficult to diagnose due to the variable presentation and lack of diagnostic criteria.

Introduction

Method

Conclusion

Myoepithelial carcinoma of the breast treated with surgery and chemotherapy

Myoepithelial carcinoma (malignant myoepithelioma) of the breast is a rare tumor, for which only a limited number of reports have been published. Most of the reports emphasized diagnosis and pathology but not biological behavior and treatment. We report a 61-year-old patient with breast myoepithelial carcinoma who developed locoregional and distant metastases and received many chemotherapy regimens. She presented with an elastic hard mass of the left breast. Breast conserving surgery was performed as part of both diagnosis and treatment. From the results of histological and immunohistochemical examinations, this case was considered to be a myoepithelial carcinoma. Fifteen months after the completion of adjuvant radiotherapy, distant metastasis of the left parasternal lymph node metastasis developed. She was treated by further excision and received a total of four regimens of chemotherapy including a combination of doxorubicin and cyclophosphamide. She received chemotherapy for 20 months after the diagnosis of metastasis.

Myoepithelial and epithelial-myoepithelial, mesenchymal and fibroepithelial breast lesions: updates from the WHO Classification of Tumours of the Breast 2012

In the 4th edition of the WHO Classification of Tumours of the Breast, myoepithelial lesions are retitled myoepithelial and epithelial-myoepithelial lesions in order to better reflect the dual participation of luminal and myoepithelial compartments in some key entities. Malignant myoepithelioma, described as a section within the chapter on myoepithelial lesions in the 3rd edition, is recognised in the 4th edition as part of metaplastic carcinoma. Adenomyoepithelioma with malignancy is categorised in terms of the cellular component undergoing malignant transformation. The list of antibodies that can be used for identifying myoepithelial cells is updated. Among mesenchymal lesions, new additions are nodular fasciitis and atypical vascular lesions, while the haemangiopericytoma is removed. The 3rd edition stated that pathological prediction of behaviour of phyllodes tumours is difficult in the individual case. In the 4th edition, some progress has been made in prioritisation and weighting of histological parameters that can potentially estimate probability of recurrence. The WHO Working Group advocates leaning towards a diagnosis of fibroadenoma in cases where there is histological uncertainty in distinction from a benign phyllodes tumour, or adopting the neutral term 'benign fibroepithelial neoplasm', as the clinical behaviour of fibroadenoma overlaps with that of benign phyllodes tumour. The 3rd edition terminology of 'periductal stromal sarcoma' is revised to 'periductal stromal tumour', akin to the widespread consensus to avoid the use of the term 'cystosarcoma' in the context of phyllodes tumours.

[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.

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.

Calponin expression in laryngeal myoepithelial carcinoma and its prognostic implications: a case report and literature review

A case report of laryngeal myoepithelial carcinoma (MEC) is presented and the literature concerning prognostic factors in MEC is reviewed. A 61-year old man was admitted to hospital with hoarseness and progressive dyspnoea. On examination, both vocal cords were fixed in the midline with a glottic fissure of only 3 mm. No tumour was seen, but the subglottis was not completely visible. A computed tomography scan showed a soft mass below the right vocal cord obstructing two-thirds of the larynx. On suspension laryngoscopy, a dull mass (1.5 x 1.5 cm) was seen below the right vocal cord, which was malignant on frozen biopsy. A total laryngectomy was performed and the patient received radiotherapy. He died of recurrence 25 months later. The tumour was positive for cytokeratin 14, S-100 protein and calponin. MEC of the larynx is extremely rare. The clinical behaviour of MEC is variable and prognostic factors have been poorly analysed. Calponin expression may be a prognostic factor, but other factors also affect the outcome in MEC.

A case of cutaneous myoepithelial carcinoma

BACKGROUND

Cutaneous myoepithelioma, both benign and malignant, is a rare neoplasm composed of neoplastic myoepithelial cells showing diverse histopathological features, and criteria for discriminating benign or malignant have not been fully clarified.

PATIENT

We present a case of cutaneous myoepithelial carcinoma in a 62-year-old woman presenting a solid mass in the right back.

RESULTS

Resected tumor was located in the whole dermis and subcutis. Histopathologically, two different growth patterns were noted: a small-nested or trabecular pattern in the superficial part and a large nodular pattern with extensive central necrosis in the deep part. Tumor cells were all epithelioid, although plasmacytoid and glycogen-rich clear cells were also observed within the large nodules of the deep part. Immunohistochemically, the cells were positive for both epithelial and myogenic markers, suggesting myoepithelial origin. Lymphatic invasion and lymph node metastasis were evident despite inconspicuous atypia and low mitotic rate.

CONCLUSION

The final diagnosis was cutaneous myoepithelial carcinoma. At present, it seems to be difficult to predict the behavior of myoepithelioma of the skin and soft tissue, although atypia and high mitotic rate are reported to be associated with local recurrence and metastasis.

The origin of vimentin expression in invasive breast cancer: epithelial-mesenchymal transition, myoepithelial histogenesis or histogenesis from progenitor cells with bilinear differentiation potential?

Vimentin expression is a rather rare finding in invasive breast cancer, and is associated with high tumour invasiveness and chemoresistance. It is currently explained by two different biological theories: direct histogenetic derivation from myoepithelial cells, and epithelial-mesenchymal transition (EMT) reflecting the end-stage of breast cancer dedifferentiation. In this study we aimed to obtain further insights into the biological hallmarks of these vimentin-expressing breast cancers. We applied immunohistochemistry for vimentin and 15 other differentiation markers to a series of 364 invasive breast cancer cases, using tissue microarray technology. 7.7% of all tumours expressed vimentin. Almost all of these cases (19/21) were Grade 3 invasive ductal carcinomas, and the majority (13/21) of these were associated with a ductal in situ component. Vimentin expression was also seen in the respective in situ components and correlated positively with the expression of SMA, CD10, CK 5, p53, Mib-1 and EGFR. A negative correlation was seen for the expression of CK 8/18 and the oestrogen receptor. Vimentin-expressing carcinomas revealed a significantly higher average absolute number of cytogenetic alterations per case, but a significantly lower frequency of chromosome 16q losses compared to vimentin-negative cases. Our present results demonstrate that, despite analogies between vimentin-positive breast cancers and myoepithelial cells in their expression of differentiation-related proteins, neither myoepithelial histogenesis nor EMT can exclusively explain the biology of these distinct tumours. This is mainly supported by the significantly higher incidence of vimentin-expressing breast cancers compared to any other myoepithelial breast tumours and the fact that vimentin is already observed in ductal in situ components. We therefore propose the alternative hypothesis that vimentin-expressing breast carcinomas may derive from breast progenitor cells with bilinear (glandular and myoepithelial) differentiation potential.

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.