Adenomyoepithelioma of the breast, a single-institution study of 17 cases

McCusker, Casey
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Adenomyoepitheliomas (AME) are rare tumours of the breast. Although they are benign, features such as local recurrence, malignant transformation and metastases are described. The objective is to report our findings on a case series of AME of the breast. A cross-sectional retrospective descriptive study was performed on cases with a diagnosis of AME. Clinical, radiological and histopathologic findings were studied. Seventeen cases were identified in 13 patients, with a median age of 50 years (34 to 79 years), in an 18-year time period from 2000 to 2018. The AMEs ranged in size from 1mm to 150mm. Intratumoural heterogeneity was evidenced by a combination of 2 and 3 low-power architectural patterns (solid, cystic, nodular) and high-power architectural patterns (papillary, pseudopapillary, trabecular, tubular), an admixture of subtypes (tubular, lobular and spindle cell) and myoepithelial cell phenotypes (spindle cell, plasmacytoid, epithelioid and clear cell). In summary, we present a case series of 17 cases of AME in which clinical features, radiological findings and histopathological features, including immunohistochemistry are detailed. Of note, we expand the size range and document unusual associations in 4 cases of lobular carcinoma in-situ (LCIS), necrotising granulomatous inflammation, clincial extension onto the chest wall and a rare case of AME with carcinoma (epithelial and myoepithelial carcinoma).
A research report in submitted format of a paper, in submission to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Medicine in the branch of Anatomical Pathology Johannesburg, 2019