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

Pleomorphic Adenoma of the Breast: A Rare Benign Lesion Masquerading as a Metaplastic Breast Carcinoma on Core-Needle Biopsy

We report a rare case of pleomorphic adenoma (benign mixed tumor) of the breast in a 66-year-old female. A 5.5 cm hypoechoic mass with lobulated margins was noted on ultrasound. A biopsy showed an atypical cartilaginous lesion, leading to a subsequent segmental mastectomy, which was initially interpreted as metaplastic breast carcinoma. On the second review at our tertiary care center, a diagnosis of a pleomorphic adenoma was favored due to the circumscription and the benign epithelial component. Due to unfamiliarity with this entity, this neoplasm has occasionally been misdiagnosed clinically and even been overcalled on core needle biopsies. Careful clinical, radiological, and pathological correlation is required to avoid unnecessarily aggressive surgery, and a differential diagnosis of pleomorphic adenoma must be included in cases of well-demarcated breast masses showing myxoid or cartilaginous changes on core-needle biopsy.

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.

A rare benign tumor of breast masquerading on fine needle aspiration cytology: A case report

Pleomorphic adenoma is a common tumor encountered in major salivary gland and very rarely seen in breast. This matrix producing tumor can be confused with fibroadenoma, phyllodes tumor and metaplastic carcinoma on fine needle aspiration cytology(FNAC). Pre-operative diagnosis of pleomorphic adenoma helps in preventing surgical over or under treatment of the disease. We present an extremely rare case of pleomorphic adenoma of breast diagnosed on FNAC with histopathological confirmation.

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.

Reporting a rare case of pleomorphic adenoma of the breast

Pleomorphic adenoma (PA) is the most common tumor type in the salivary gland. PA is uncommon in the breast tissue. Only 73 cases of PA of the breast have been reported in the world literature. We are reporting the 74th case of PA of the breast. A 61-year-old woman was referred to Shahid Beheshti Hospital Obstetric Clinic with bloody painless discharge from the right nipple. A bean size mass was detected immediately below the right nipple. After an excisional biopsy, the pathologist found proliferation in epithelial and myoepithelial cells that had small and multiple nuclei, myxoid and chondroid stroma. Immunohistochemistry stain was positive for S-100 and patchy for GFAP in tumor cells and for SMA around the tubule-glandular and tumor cell aggregates and suggested PA of the breast. It is essential for the pathologists to consider PA of the breast as a differential diagnosis of a rounded circumscribed mass in the juxta-areolar areas. Careful paraffin sections should be performed to avoid an unnecessary mastectomy.

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.

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.

[Salivary gland-like tumors of the breast]

A subset of rare benign and malignant breast tumors with and without myoepithelial differentiation are morphologically and histogenetically similar to salivary gland tumors, but may differ in incidence and clinical behavior. The clinicopathological, immunohistochemical, molecular and prognostic features of ten salivary gland-like tumor entities of the breast are discussed and compared with their respective counterparts in the salivary glands.

Pleomorphic adenoma (benign mixed tumor) of the breast: A case report and review of the literature

We report a case of pleomorphic adenoma (benign mixed tumor) of the breast, which is an extremely rare location for this tumor. Examination of a 55-year-old woman unexpectedly revealed a mass measuring 0.8 cm in diameter in the subareolar region of the right breast. Excisional biopsy was performed, and the tumor histologically showed pleomorphic adenoma composed of duct epithelial cells, myoepithelial cells, and a myxochondroid matrix. Immunohistochemically, duct epithelial cells were positive for the estrogen receptor, but negative for the progesterone receptor. The nuclei of the spindle and myoepithelial cells were immunoreactive for HMGI-C and HMGI(Y) proteins, indicating a histogenesis similar to pleomorphic adenoma of the salivary glands. Interphase fluorescence in situ hybridization performed on paraffin-embedded tissue sections with 12q15 probes and a 6p21 probe demonstrated no chromosomal rearrangement. Sixty-nine cases of this type of tumor arising in the breast have been described previously. Using imaging procedures, the tumor has occasionally been misdiagnosed as malignant clinically and even pathologically in frozen section diagnosis. Careful diagnosis based on paraffin sections is required to avoid unnecessary aggressive surgery, and pathologists should include pleomorphic adenoma in the differential diagnosis of a demarcated, juxtaareolar, small hard mass.

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

Pleomorphic adenoma of the breast (PAB) is a very rare neoplasm. Although quite unique in its morphology, PAB shares some similarities with adenomyoepithelioma and is considered by some authors as a variant of this entity. Cytologic diagnosis of this lesion can be very challenging, especially when limited sampling is available. The differential diagnosis of PAB includes metaplastic carcinoma. On cytologic material, fibroadenoma and phyllodes tumor should also be considered within the differential diagnosis. We report the findings in a case of PAB, initially misdiagnosed as mucinous carcinoma on fine-needle aspiration, and review the literature regarding this entity. Correct identification of this benign mammary neoplasm is important to avoid unnecessarily aggressive treatment.

Carcinoma ex-pleomorphic adenoma of the breast. Report of three cases suggesting a relationship to metaplastic carcinoma of matrix-producing type

Three cases of carcinoma ex-pleomorphic adenoma of the breast are reported. Patients were 82, 60 and 56 years old and presented with a breast lump. All tumours showed areas of pleomorphic adenoma adjacent to typical areas of malignant transformation. These cases add to the spectrum of tumours shared by breast and salivary gland. The relationship between these neoplasms and metaplastic carcinoma of matrix-producing type is discussed.

Salivary gland-like tumours of the breast: surgical and molecular pathology

Breast glands and salivary glands are tubulo-acinar exocrine glands that can manifest as tumours with similar morphological features, but that differ in incidence and clinical behaviour depending on whether they are primary in breast or salivary glands. Salivary gland-like tumours of the breast are of two types: tumours with myoepithelial differentiation and those devoid of myoepithelial differentiation. The first and more numerous group comprises a spectrum of lesions ranging from "bona fide" benign (such as benign myoepithelioma and pleomorphic adenoma), to low grade malignant (such as adenoid cystic carcinoma, low grade adenosquamous carcinoma, and adenomyoepithelioma), to high grade malignant lesions (malignant myoepithelioma). The second group comprises lesions that have only recently been recognised, such as acinic cell carcinoma, oncocytic carcinoma of the breast, and the rare mucoepidermoid carcinoma.