Pleomorphic adenoma of the breast: Case report and review of the literature

Diagnostic Challenges and Pitfalls of Mammary Pleomorphic Adenoma Illustrated by a Case Report

Mammary pleomorphic adenoma is a biphasic tumor, characterized by epithelial-myoepithelial components with myxochondroid stroma, resembling the prototypic pleomorphic adenoma of the salivary glands. We report the multiple diagnostic pitfalls raised by a mammary pleomorphic adenoma, initially diagnosed as mucinous carcinoma on fine-needle aspiration (FNA) cytology and invasive carcinoma on needle core biopsy. The final diagnosis was made on the surgical specimen. As the term “pleomorphic” suggests, this tumor can present various phenotypes, some of which might be misleading on both FNA cytology or needle core biopsy. Rearrangements in PLAG1 and HMGA2 genes have not been detected in our patient. Mammary pleomorphic adenoma is considered a benign tumor, despite rare local recurrence and malignant behavior. Its correct identification, despite the difficulties, is essential to avoid unnecessary aggressive treatment.

A case of pleomorphic adenoma of the breast on dynamic contrast-enhanced MR imaging

Pleomorphic adenoma commonly develops in the salivary gland, but rarely in the breast. The dynamic contrast-enhanced MR imaging findings of pleomorphic adenoma of the breast have not been well described. We report a 43-year-old woman with pleomorphic adenoma of the left breast. The imaging findings, including those on dynamic contrast-enhanced MR imaging, included an oval mass with a smooth margin, which consisted of solid and cystic components. The solid component was hypo-intense on T1-weighted imaging, hyper-intense on short tau inversion recovery imaging, with no apparent restricted diffusion, and had heterogeneous enhancement with dark internal septation and a fast/plateau dynamic contrast enhancement pattern. The cystic component was slightly hyper-intense on T1-weighted imaging, slightly hypo-intense on short tau inversion recovery imaging and had no apparent restricted diffusion or contrast enhancement. Together with its rarity, the similarities of imaging findings and the pathologic findings of pleomorphic adenoma of the breast to those of other tumors make accurate preoperative diagnosis difficult. Therefore, through this case report, awareness of pleomorphic adenoma of the breast on dynamic contrast-enhanced MR imaging will facilitate appropriate surgery and postoperative observation based on an accurate diagnosis.

Pleomorphic adenoma of the breast with cytologic atypia on cytopathology: A potential diagnostic pitfall and literature review

Pleomorphic adenoma of the salivary gland is a well-established and recognized diagnosis; however, pleomorphic adenomas of the breast are rare and can be difficult to diagnose on cytology or intraoperatively. We report a case that was misdiagnosed on a fine needle aspiration and frozen section. The pitfalls, differential diagnoses, and current management are discussed.

A Case of Adenomyoepithelioma With a Pleomorphic Adenoma-Like Component of the Male Breast

Adenomyoepithelioma (AME) of the male breast is a rare tumor characterized by biphasic proliferation of gland epithelial cells and myoepithelial cells. Though pleomorphic adenoma (PA) is also known to be an epithelial-myoepithelial tumor in the breast, and these tumors are considered to exist on the same spectrum by some authors, to the best of our knowledge, there have been no reports of a clear transition from AME to PA in the male breast. Therefore, the case of an 85-year-old man with AME with PA-like components is presented.

Radiologic Findings of a Rare Subtype of Invasive Breast Cancer with Poor Prognosis: Metaplastic Carcinoma of the Breast

BACKGROUND AND OBJECTIVES

The purpose of this study was to evaluate the mammographic, sonographic and MRI findings of metaplastic breast carcinoma.

METHODS

In this retrospective review study, we analyzed the medical files of 9600 patients who were treated for invasive breast cancers. Clinical information, histopathologic and radiologic findings of 65 patients were included in this study. All existing radiologic images and medical reports were reviewed retrospectively. Thirty-three patients had MG, 58 patients had US and 7 patients had MRI imaging results.

RESULTS

Mammographically, the most frequent presentations of MPBC were round shape, microlobulated margin and high density masses. Calcifications with or without masses were not a frequent finding. The most common sonographic findings were round shape, partially indistinct angular margin, hypoechoic and heterogeneous echo patterns and no posterior feature masses. All lesions were presented as masses rather than non-mass enhancements on magnetic resonance imaging. Features of masses had more malignant feature on MRI than other modalities in all 7 patients.

CONCLUSION

Metaplastic breast carcinoma is one of the rarest poorly differentiated invasive breast carcinomas. Interestingly, these aggressive tumors demonstrate benign or moderately malign features on imaging methods. This appearance of MPBC can cause it to be misdiagnosed as a benign breast lesion especially in young women. MPBC should be kept in mind in the differential diagnosis of large palpable breast masses. Therefore, follow-up at short intervals and/or multimodality imaging studies which include breast MRI are important for the diagnosis of MPBC.

A Comparative Review of Mixed Mammary Tumors in Mammals

Mixed tumors are characterized by the histological identification of two or more cell types. Commonly, a mixture of epithelial and myoepithelial cells is included in abundant stroma, which can consist of myxoid, chondroid or bony matrices. Spontaneously arising mixed tumors are rare lesions in the human breast but are common in human salivary glands and canine mammary glands. Subtle histopathological characteristics and overlapping attributes of malignant lesions with other benign lesions can lead to a diagnostic challenge. Mixed tumors can present as benign or malignant. While malignant mixed tumors are quite rare in the human breast they have a poor prognosis. Benign mixed mammary tumors occur more frequently in female dogs than in humans and are usually associated with a good prognosis. This review will provide a comprehensive overview of mixed mammary tumors, across various mammalian species.

Diagnosis of an extremely rare pleomorphic adenoma of the breast with core needle biopsy: A case report

INTRODUCTION

Pleomorphic adenoma (PA) rarely originates in the mammary gland. This tumor is a benign mixed tumor and is commonly found in the salivary glands, but rarely shows findings similar to those of breast cancer. The tumor is misdiagnosed in 30-50% of the patients, including overdiagnosis of malignancy preoperatively, leading to unnecessary surgery for breast cancer.

CASE PRESENTATION

The present patient was a 45-year-old woman who exhibited no subjective symptoms. She visited the Takahashi Breast and Gastroenterology Clinic for breast cancer screening. A mass measuring 1.5 cm was palpated in the E region of the left breast. Mammography (MMG) showed a tumor shadow in the left S region. There was a high-density area inside the tumor, suggesting bone or cartilage formation, and a diagnosis of category 3 on MMG was made. Ultrasonography (US) revealed a poorly demarcated tumor measuring 14.3 × 14.8 × 10.7 mm with relatively smooth margins and inhomogeneous high-echo content. Core needle biopsy (CNB) was performed, which led to the diagnosis of PA. The tumor showed proliferation of small cells forming glandular duct-like structures or anastomosed funicular structures. Moreover, the cells in the basilar portion were spindle shaped and transitioned to the stroma. Cartilaginous metaplasia, calcification, and ossification were observed in some areas. Intraductal papilloma was also observed in some areas.

CONCLUSION

PA may be diagnosed based on the histological findings of CNB. Thus, unnecessary surgery for breast cancer may be avoided.

Pleomorphic adenoma of breast: a radiological and pathological study of a common tumor in an uncommon location

Pleomorphic adenoma occurs commonly in the major salivary glands but is uncommonly encountered in the breast. In both of these locations, the tumor is typically grossly circumscribed and has a “mixed” histological appearance, being composed of myoepithelial and epithelial components amid a myxochondroid matrix. Herein, we report a case of pleomorphic adenoma of the breast which was preoperatively thought to represent a fibroadenoma on clinical and radiological grounds. It is the rarity of the tumor in the breast, rather than its histological appearance, that causes diagnostic difficulty.

Combined Epithelial-Myoepithelial Lesions of the Breast

Epithelial-myoepithelial proliferations of the breast are a heterogeneous poorly defined group of lesions characterized morphologically by dual differentiation into ductal (luminal) and myoepithelial cells. They include neoplastic and non-neoplastic entities that have overlapping morphologic features that may give rise to diagnostic difficulty. Many of these entities are low grade or of uncertain malignant potential but the biology of some of these rare lesions remains to be elucidated. This article discusses the differential diagnosis of epithelial-myoepithelial lesions of the breast and highlights the morphologic features of some of these entities.

Adenomyoepithelioma of the breast: a review stressing its propensity for malignant transformation

This review describes the classification, clinical presentation, pathological features and clinical behaviour of adenomyoepithelioma (AME) of the breast. It is based on an extensive review of the literature and study of a collection of cases built up over a 17-year period at the British Columbia Cancer Agency. The diversity of the morphology encountered in both benign and malignant AME is described. The behaviour of malignant AME seems to be related to the grade of the malignant component.

Salivary gland-type tumors of the breast: a spectrum of benign and malignant tumors including "triple negative carcinomas" of low malignant potential

Salivary gland-type neoplasms of the breast are uncommon and comprise numerous entities analogous to that more commonly seen in salivary glands. The clinicopathologic spectrum ranges from benign to malignant but there are important differences as compared with those of their salivary counterpart. In the breast, benign adenomyoepithelioma is recognized in addition to malignant one, whereas in the salivary gland a histologically similar tumor is designated as epithelial-myoepithelial carcinoma without a separate benign subgroup. Mammary adenoid cystic carcinoma is a low-grade neoplasm compared with its salivary equivalent. It is also important to appreciate that in contrast to "triple negative" conventional breast carcinomas with aggressive course, most salivary-type malignant breast neoplasms behave in a low-grade manner. Most of these tumors are capable of differentiating along both epithelial and myoepithelial lines, but the amount of each lineage-component varies from case to case, contributing to diagnostic difficulties. Well established examples of this group include pleomorphic adenoma, adenomyoepithelioma, and adenoid cystic carcinoma. Another family of salivary gland-type mammary epithelial neoplasms is devoid of myoepithelial cells. Key examples include mucoepidermoid carcinoma and acinic cell carcinoma. The number of cases of salivary gland-type mammary neoplasms in the published data is constantly increasing but some of the rarest subtypes like polymorphous low-grade adenocarcinoma and oncocytic carcinoma are "struggling" to become clinically relevant entities in line with those occurring more frequently in salivary glands.