A Rare Case of Adenomyoepithelioma of the Breast Complicated with Cyst Diagnosed by Preoperative Core Needle Biopsy: A Case Report.

introductionAdenomyoepithelioma (AME) of the breast is a rare benign disease in which glandular epithelial cells and myoepithelial cells proliferate to form a mass. Preoperative diagnosis is considered difficult, and diagnosis by core needle biopsy (CNB) is particularly difficult. Due to its heterogeneous features and growth patterns of the tumor cells constructing the tumor mass, this tumor, although benign in nature, is misdiagnosed as ordinary breast cancer and often treated by surgery for breast cancer. Here, a rare case of AME of the breast complicated with cysts diagnosed by preoperative CNB is reported. CASE PRESENTATION: A 27-year-old female presented with a chief complaint of a lump in the upper-inner quadrant of the left breast that had been present for 6 months. Bloody discharge had been noted from the left nipple for 1 week prior to her visit. A mass was palpable on physical examination. Mammography and ultrasonography detected a cystic mass and a solid mass in the upper-inner quadrant of the left breast. Fine-needle aspiration of the cystic mass revealed blood-derived cells and foam cells. CNB of the solid mass in the left breast revealed small and large ducts within a cyst, with myoepithelial cells proliferating between them. The stroma exhibited mucinous edema-like changes. Immunohistochemical staining for p63 and alpha-smooth muscle actin confirmed the proliferation of myoepithelial cells. The diagnosis of CNB was benign AME. Subsequently, the left breast mass was resected. The final pathological diagnosis was benign AME.

conclusionsHere, a rare case of AME of the breast complicated with cysts diagnosed by preoperative CNB is reported.