Metastatic myoepithelioma of the breast. ANZ J Surg

Department of Medical Oncology, Royal Melbourne Hospital, Grattan Street, Parkville, Victoria 3050, Australia.
ANZ Journal of Surgery (Impact Factor: 1.12). 01/2005; 74(12):1135-7. DOI: 10.1111/j.1445-1433.2004.03252.x
Source: PubMed


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.

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    • "It usually presents as a palpable nodule, and a mammographic density without distinctive features. Most are benign, and only few malignant cases have been reported in the literature [1-4]. The patient age may range from 22 to 87 years. "
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    ABSTRACT: Myoepithelioma of the breast is a rare tumor and the cytologic features have only been described in one previous report. 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 x 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. 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.
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    ABSTRACT: Zusammenfassung Eine kleine Gruppe benigner und maligner Mammatumoren mit oder ohne myoepitheliale Differenzierung weist morphologische und histogenetische Ähnlichkeiten mit Speicheldrüsentumoren auf, sie zeigen aber Unterschiede hinsichtlich ihrer Inzidenz und ihres klinischen Verhaltens. Die klinischen, histologischen, immunhistochemischen, molekularpathologischen und prognostischen Eigenschaften von 10 Entitäten speicheldrüsenähnlicher Mammatumoren werden in der vorliegenden Übersicht erörtert und mit ihren Analoga in den Speicheldrüsen verglichen.
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    ABSTRACT: A subset of rare benign and malignant breast tumors with and without myoepithelial differentiation are morphologically and histogenetically similar to salivary gland tumors, but may differ in incidence and clinical behavior. The clinicopathological, immunohistochemical, molecular and prognostic features of ten salivary gland-like tumor entities of the breast are discussed and compared with their respective counterparts in the salivary glands.
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