Pleomorphic adenoma of Breast Mimicking as cancer: A Rare Case presentation

Introduction: Pleomorphic adenoma (PA) is a benign neoplasm which most commonly occurs in the parotid gland but has only rarely been described in the breast.[1] The rarity of PA in the breast, as well as its unusual appearance, has contributed to misdiagnosis in this location [2, 3]. PAs are considered to be a variant of intraductal papilloma or adenomyoepithelioma [4] and are typically found in the subareolar region [5, 6].Case Report: A 64-year-old woman presented with a palpable mass in the right breast. The preoperative clinical and radiological impression was that of a breast cancer. A firm, well-circumscribed, 5 cm, mass was excised. Serial sectioning revealed whitish, homogeneous, cut surfaces . Microscopically, the tumor was comprised of an admixture of stromal and epithelial elements. The dominant stromal component was characterized by bland spindled myoepithelial cells embedded in a largely myxoichondroid matrix (Figures (A) and (B)). The epithelial component, represented by scattered compressed glands interspersed in the stroma, was cytologically insipid and mitotically quiescent (Figure (c)) Discussion: PA is the most common benign tumor of the parotid gland; however, it is among the least common neoplasms of the mammary gland. In the latter location, it afflicts primarily adult females and typically presents as a solitary palpable central mass [4, 8, 9]. Published cases of mammary PAs have ranged in size from 0.6 cm to 17 cm, with most spanning ~2 cm [10–12]. PA can also occur, albeit most uncommonly, in the skin, vulva, and upper respiratory tract [13]. In all its primary locations, PA generally behaves in an indolent manner and neither recurs nor metastasizes following complete resection; nevertheless, at least 3 cases of malignant PA (i.e., carcinoma ex PA) in the breast have been reported [7]. It is notable that benign PAs of the breast have been mistaken for mucinous carcinoma [3] and metaplastic carcinoma [2], on limited samples of fine needle aspirates (FNA) and needle core biopsies (NCB), respectively—the perfidious myxoid matrix proving to be the diagnostic pitfall in these instances.In summary, we report a case of mammary PA—which was clinically and radiologically suspected to be a breast cancer. Histologically, the tumor demonstrated the characteristic histopathological features of a PA. Pathologists should keep this tumor in mind whenever a tumor with prominent myxochondroid appearance is encountered—particularly in aspiration cytology or needle core biopsy material.

کلیدواژه ها:

Pleomorphic adenoma ، breast ، cancer