28646 – BREAST ADENOMIOEPITHELIOMA: A CASE REPORT

Abstract

Introduction: Initially described in the literature by Hamperl in 1970, breast adenomyoepithelioma (AME) is a rare tumor
that can mimic other epithelial, myoepithelial, or biphasic lesions of the breast. It is characterized by a dual proliferation of myoepithelial and luminal cells, with variable biological behavior, most of which are benign. In the classification
published by the World Health Organization in 2019, AME was defined as an epithelial-myoepithelial lesion of the breast.
Malignant transformation of this tumor is a rare event, which can occur in one or both cellular components. There are no
specific features on imaging or clinical examination that facilitate diagnosis, often leading to interpretative errors; histological and immunohistochemical analyses are necessary for definitive diagnosis. Mammographic and MRI features
are nonspecific and rarely show microcalcifications. Ultrasound typically reveals an oval, hypoechoic, solid mass with
irregular borders. Most cases occur in women in their fifth or sixth decade of life but can arise at any age. The differential
diagnosis of AME includes a wide spectrum of entities, such as papillary hyperplasia with myoepithelial features, fibroadenoma, phyllodes tumor, adenoma, tubular carcinoma, microglandular adenosis, adenoid cystic carcinoma, pleomorphic
adenoma, and mesenchymal stromal proliferations. Immunohistochemical findings aid in establishing the correct diagnosis. Treatment consists of wide surgical excision due to the risk of local recurrence. Here, we report an uncommon case
of a young woman with a palpable, benign breast adenomyoepithelioma. Methodology: Descriptive study. Case report.
Conclusion: Breast adenomyoepithelioma (AME) is a rare condition that can pose diagnostic challenges, both regarding imaging findings, due to their nonspecific nature, and the need for immunohistochemistry for definitive diagnosis.
Management of AME is not guided by clear protocols given the rarity of cases, but a literature review has shown that
wide surgical excision with clear margins is sufficient for benign forms, which constitute the majority of cases, including
our report.