Pleomorphic adenoma of the breast: a clinicopathologic and immunohistochemical study of 10 cases

Salivary gland-like tumors of the breast: Histopathologic and genetic features with clinical implications

Salivary gland-like tumors of the breast are rare neoplasms that share morphologic, immunophenotypic, and/or genetic features with their salivary gland counterparts, highlighting a shared underlying histopathogenesis in most cases. Salivary gland-like carcinomas included in the World Health Organization classification of breast tumors are adenoid cystic carcinoma, secretory carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, and the exceedingly rare polymorphous adenocarcinoma. These carcinomas are usually triple negative for estrogen receptor and progesterone receptor expression and HER2 overexpression, yet generally have favorable prognosis, in contrast to high-grade triple negative carcinomas of no special type. On the other hand, a small subset, such as solid-basaloid adenoid cystic carcinoma, rare high-grade carcinomas, and those associated with transformation to other types of high-grade invasive carcinoma can behave more aggressively. Other salivary gland-like tumors of the breast, such as pleomorphic adenoma and adenomyoepithelioma, are usually benign but can rarely undergo malignant transformation. Although clinical experience with salivary gland-like breast tumors is overall limited, their recognition and accurate classification has important implications for prognosis and clinical management, especially to avoid overtreatment of salivary gland-like carcinomas. The identification of characteristic genetic alterations and/or immunohistochemical surrogates in many of these tumors has practical applications to establishing an accurate diagnosis and directing clinical management. This review highlights the histopathologic and genetic characteristics of salivary gland-like breast tumors and the implications of the diagnosis for current clinical management.

Salivary Gland-like Tumors of the Breast

CONTEXT

The World Health Organization classification of tumors of the breast recognizes several special type carcinomas and benign lesions with features comparable to those of salivary gland tumors.

OBJECTIVE

To discuss the histologic, immunophenotypic, molecular, and clinical features of salivary gland-like carcinomas of the breast. These breast tumors are often negative for hormone receptors and human epidermal growth factor receptor 2 (HER2), that is, triple-negative, but they generally have a much better prognosis than triple-negative breast carcinomas of no special type. We compare the immunophenotypic, molecular, and clinical features of these breast tumors with their salivary gland counterparts, highlighting similarities and differences. We also discuss benign salivary gland-like breast tumors. Finally, we highlight recent developments in understanding the molecular pathogenesis of these breast tumors and novel ancillary studies that can be used to support their diagnosis.

DATA SOURCES

A literature review was conducted, and papers were selected for further analysis and discussion by the authors of this review based on their novelty, applicability, and impact in the field.

CONCLUSIONS

Breast tumors that exhibit morphologic overlap with salivary gland tumors have been recognized by pathologists for decades, but the similarities and differences in their molecular pathogenesis have not been understood until more recently. These developments have led to novel diagnostic tools and further knowledge of these rare breast lesions.

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.

Breast lesions with myoepithelial phenotype

Myoepithelial cells (MECs) constitute a continuous layer of cells surrounding the breast glands, localised between the epithelial cells (ECs) and the basal membrane. MECs play important roles in normal mammary gland as they produce basal membrane and stimulate secretion. During neoplastic transformation, MECs act as a barrier preventing stromal invasion. MECs themselves can undergo a great variety of changes, ranging from hyperplastic to metaplastic, to neoplastic, and giving rise to a wide spectrum of morphological pictures sometimes difficult to interpret on routine diagnoses. Several benign and malignant breast tumours can present features of MECs differentiation. As these latter tumours are quite infrequent, the purpose of the present study is to offer a review of the morphological spectrum of MECs lesions, with correlations to prognosis.

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.

Breast lesions of uncertain malignant nature and limited metastatic potential: proposals to improve their recognition and clinical management

Breast lesions comprise a family of heterogeneous entities with variable patterns of presentation, morphology and clinical behaviour. The majority of breast lesions are classified traditionally into benign and malignant conditions and their behaviour can, in the vast majority of cases, be predicted with a reasonable degree of accuracy. However, there remain lesions which show borderline features and lie in a grey zone between benign and malignant, as their behaviour cannot be predicted reliably. Defined pathological categorization of such lesions is challenging, and for some entities is recognized to be subjective and include a range of diagnoses, and forms of terminology, which may trigger over- or undertreatment. The rarity of these lesions makes the acquisition of clinical evidence problematic and limits the development of a sufficient evidence base to support informed decision-making by clinicians and patients. Emerging molecular evidence is providing a greater understanding of the biology of these lesions, but this may or may not be reflected in their clinical behaviour. Herein we discuss some breast lesions that are associated with uncertainty regarding classification and behaviour, and hence management. These include biologically invasive malignant lesions associated with uncertain metastatic potential, such as low-grade adenosquamous carcinoma, low-grade fibromatosis-like spindle cell carcinoma and encapsulated papillary carcinoma. Other lesions of uncertain malignant nature remain, such as mammary cylindroma, atypical microglandular adenosis, mammary pleomorphic adenoma and infiltrating epitheliosis. The concept of categories of (1) breast lesions of uncertain malignant nature and (2) breast lesions of limited metastatic potential are proposed with details of which histological entities could be included in each category, and their management implications are discussed.

Benign mixed tumour of the breast and breast skin, two cases with diagnostic difficulties

We present two cases of pleomorphic adenoma, one that developed in the breast parenchyma and the other in the breast skin, with their histopathological differential diagnosis.

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.

Immunohistochemical expression of myoepithelial markers in adenomyoepithelioma of the breast: a unique paradoxical staining pattern of high-molecular weight cytokeratins

To determine which immunohistochemical markers are useful for the identification of neoplastic myoepithelial cells in adenomyoepithelioma of the breast, the expression of seven myoepithelial markers (α-smooth muscle actin (α-SMA), calponin, p63, CD10, cytokeratin 5/6, cytokeratin 14, and S-100) was examined in 19 lesions from 16 patients. The lesion consisted of seven spindle and 12 clear cell lesions. For normal myoepithelial cells, α-SMA, calponin, and p63 were significantly more sensitive than cytokeratin 5/6, cytokeratin 14, and S-100. There was no significant difference in the expression of α-SMA, calponin, p63, and CD10 in neoplastic myoepithelial cells of adenomyoepithelioma regardless of spindle or clear cell types. In spindle cell lesions, high-molecular weight cytokeratins (HMWCK; cytokeratin 5/6 and cytokeratin 14) tended to show higher staining scores and S-100 showed lower staining scores than other markers. In clear cell lesions, HMWCK showed significantly lower staining scores than the other five markers. There was no significant difference in staining scores among the other five markers. HMWCK showed a unique paradoxical staining pattern in clear cell lesions, with diffusely positive inner epithelial cells and completely negative outer myoepithelial cells. Although the sensitivity of HMWCK in clear cell lesions is low, with this unique paradoxical staining pattern and relatively high sensitivity in spindle cell lesions, HMWCK could be useful in diagnosing adenomyoepithelioma. In choosing immunohistochemical markers, any of the seven markers are useful, but combining HMWCK and any one of α-SMA, calponin, and p63 would be a good panel for the diagnosis of adenomyoepithelioma.

Pleomorphic adenoma of breast-a case report and review of literature

Pleomorphic adenoma (PA) is a rare benign tumour of the breast. However inadequate surgery of this tumour, which is notorious for its pseudopod like extension into adjacent tissue, results in recurrence. We report a case of pleomorphic adenoma of the breast that has been excised at a local hospital and then referred to a tertiary care hospital for definite management. The diagnostic dilemmas and optimal management, of such cases where dependable pathology report and details of primary surgery are often not available, are discussed.

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.

K5/K14-positive cells contribute to salivary gland-like breast tumors with myoepithelial differentiation

Salivary gland-like tumors of the breast show a great variety of architectural patterns and cellular differentiations such as glandular, myoepithelial, squamous, and even mesenchymal phenotypes. However, currently little is known about the evolution and cellular differentiation of these tumors. For that reason, we performed an in situ triple immunofluorescence lineage/differentiation tracing (isTILT) and qRT-PCR study of basal (K5/K14), glandular (K7/K8/18), and epidermal-specific squamous (K10) keratins, p63, and smooth muscle actin (SMA; myoepithelial marker) with the aim to construct and trace different cell lineages and define their cellular hierarchy in tumors with myoepithelial differentiation. isTILT analysis of a series of 28 breast, salivary, and lacrimal gland tumors, including pleomorphic adenomas (n=8), epithelial-myoepithelial tumors (n=9), and adenoid cystic carcinomas (n=11) revealed that all tumor types contained K5/K14-positive progenitor cells in varying frequencies from a few percent up to 15%. These K5/K14-positive tumor cells were found to differentiate to glandular- (K8/18-positive) and myoepithelial-lineage (SMA-positive)-specific cells and were also shown to generate various heterologeous cell differentiations such as squamous and mesenchymal progenies. p63 was co-expressed with K5/K14 in basal-like progenitor cells, myoepithelial, and squamous cells but not in glandular cells. Our results show that the corresponding counterpart tumors of breast and salivary/lacrimal glands have identical cellular compositions. Taken together, our isTILT and RNA-expression data indicate that look-alike tumors of the breast represent a special subgroup of basal-type tumors with benign or usually low malignant potential.

Myoepithelial and epithelial-myoepithelial, mesenchymal and fibroepithelial breast lesions: updates from the WHO Classification of Tumours of the Breast 2012

In the 4th edition of the WHO Classification of Tumours of the Breast, myoepithelial lesions are retitled myoepithelial and epithelial-myoepithelial lesions in order to better reflect the dual participation of luminal and myoepithelial compartments in some key entities. Malignant myoepithelioma, described as a section within the chapter on myoepithelial lesions in the 3rd edition, is recognised in the 4th edition as part of metaplastic carcinoma. Adenomyoepithelioma with malignancy is categorised in terms of the cellular component undergoing malignant transformation. The list of antibodies that can be used for identifying myoepithelial cells is updated. Among mesenchymal lesions, new additions are nodular fasciitis and atypical vascular lesions, while the haemangiopericytoma is removed. The 3rd edition stated that pathological prediction of behaviour of phyllodes tumours is difficult in the individual case. In the 4th edition, some progress has been made in prioritisation and weighting of histological parameters that can potentially estimate probability of recurrence. The WHO Working Group advocates leaning towards a diagnosis of fibroadenoma in cases where there is histological uncertainty in distinction from a benign phyllodes tumour, or adopting the neutral term 'benign fibroepithelial neoplasm', as the clinical behaviour of fibroadenoma overlaps with that of benign phyllodes tumour. The 3rd edition terminology of 'periductal stromal sarcoma' is revised to 'periductal stromal tumour', akin to the widespread consensus to avoid the use of the term 'cystosarcoma' in the context of phyllodes tumours.

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.

Origin and differentiation of breast nipple syringoma

Similarities in morphology and in glandular and squamous differentiation patterns amongst syringomas of the breast nipple and of the skin suggest a common nature, but the origin of nipple syringoma remains undefined. Using triple immunofluorescence analysis, we found that cells immunopositive for basal keratins K5 and 14 undergo differentiation into glandular and squamous cell lineages. Both tumour types expressed K10, indicative of squamous lineage, but there were specific differences in their glandular lineage. In contrast to the breast nipple syringoma, which expressed glandular keratins K8/18/19, syringoma of the skin only expressed the glandular keratin K19. Therefore, syringomas of the breast nipple and of the skin resemble glandular lineages of the breast nipple duct or eccrine duct epithelium, respectively. From these results we conclude that K5/14-positive cells of the breast nipple ducts are the putative cells of origin for syringomas of the nipple, which highlights the organotypic glandular differentiation potential.

Malignant mixed tumor of the soft tissue occurring after total knee arthroplasty

A 70-year-old woman developed a malignant mixed tumor of the soft tissue 2 years after total knee arthroplasty. A 5×3×3-cm elastic hard tumor at the lateral side of the surgical scar was resected. The tumor showed focal infiltration into surrounding adipose and fibrous tissues, focal necrosis, and vascular infiltration. It was diagnosed as malignant. Mixed tumor, or myoepithelioma, of the soft tissue is a relatively rare tumor that was recently recognized as a disease entity; the vast spectrum of myoepithelial cell differentiation and the resultant morphologic diversity might increase the difficulty of the histological diagnosis. Postoperatively, the patient did not receive adjuvant therapy and no recurrence of the tumor was observed for 6 years. Range of motion of her left knee is -5° extension and 90° flexion; however, her activities of daily living are restricted because of general fatigue, partly due to hepatoma and chemotherapy.Despite the increase of artificial implant use worldwide, reports of peri-implant tumor formation are rare. Although we do not know the exact mechanism of tumor genesis, we consider the fibroblast formation in the routine healing process to be a possible mechanism. Further investigation is necessary to identify coexisting factors that increase the risk of tumor formation after implantation.

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.

Expression of matrix metalloproteinases MMP-2, MMP-9 and their tissue inhibitors TIMP-1 and TIMP-2 in the epithelium and stroma of salivary gland pleomorphic adenomas

AIMS

The balance between matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) is involved in the morphogenesis of normal salivary gland as well as in the mechanisms of tumour invasion and metastasis. The role of MMPs and TIMPs in pleomorphic adenoma has not been elucidated sufficiently. Our aim was to analyse the mRNA and protein expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 in the epithelium and stroma of pleomorphic adenoma and to evaluate their roles.

METHODS AND RESULTS

In each sample from six patients, cells from the epithelium and stroma were obtained by laser microdissection. The mRNA expression of MMPs and TIMPs was determined by real-time quantitative reverse transcriptase-polymerase chain reaction and protein expression was confirmed by immunohistochemistry. Results showed that mRNA expression of MMPs and TIMPs was significantly higher in stroma than in epithelium in most patients. MMPs and TIMPs were immunoreactive mainly in epithelium rather than in stroma.

CONCLUSIONS

Our results provide preliminary evidence that stromal myoepithelium may be the primary source of MMPs and that the stroma has the potential to play a more important role than ductal epithelium in biological behaviour of pleomorphic adenomas. These findings seem worthy of further investigation.

Apocrine mixed tumor of the skin (“mixed tumor of the folliculosebaceous-apocrine complex”)

BACKGROUND

A systematic analysis of the entire spectrum of various forms of differentiation and metaplastic epiphenomena in cutaneous apocrine mixed tumor (AMT) has never been performed.

OBJECTIVE

The purpose of our study was to study a large number of cutaneous mixed tumors so as to fully characterize the entire spectrum of differentiations and metaplastic changes that may occur in the epithelial, myoepithelial, and stromal components of AMT.

METHODS

This article reports a light-microscopic study of 244 cases of cutaneous AMT, complemented by a literature review.

RESULTS

All types of differentiation along the lines of the folliculosebaceous-apocrine unit can be seen in AMT. The spectrum of metaplastic changes in the epithelial components includes squamous metaplasia, mucinous metaplasia, oxyphilic metaplasia, clear cell change, columnar metaplasia, hobnail metaplasia, and cytoplasmic vacuolization. The following changes in the myoepithelial component were documented: clear cell change, hyaline cells, plasmacytoid cells, spindling, and collagenous spherulosis. Stromal alterations included chondroid metaplasia, osseous metaplasia, and adipose metaplasia.

LIMITATIONS

This study utilizes tissue specimens that mainly came as consultations; therefore some inherent selection bias exists.

CONCLUSIONS

AMT displays a wide range of differentiation and metaplastic changes in its epithelial, myoepithelial, and stromal components. These phenomena are not mutually exclusive. When unduly prominent, they may present diagnostic pitfalls. Our findings corroborate those of previous publications, stressing the remarkable diversity of differentiation and metaplasias that may be found in cutaneous AMT. We propose that the most appropriate name for these lesions is "mixed tumor of the folliculosebaceous-apocrine complex."

Pleomorphic Adenoma of the Breast Should Be Excised with a Cuff of Normal Tissue

Pleomorphic adenoma is a benign tumor found rarely in the breast but commonly in the salivary gland. Unlike the salivary gland variant management guidelines are poorly defined in the breast. We describe the first case of pleomorphic adenoma of the breast that has recurred for the second time following previous surgical excisions, and review the available literature. Due to the risk of recurrence and malignant transformation, we recommend complete excision of the lesion with a cuff of normal tissue, as is the practice in the salivary gland. Clinicians should be aware of the condition, as preoperative diagnosis will facilitate adequate surgery. Patients should be informed about the risk of recurrence. We recommend follow-up for at least a period of 5 years with yearly clinical examinations.

Pleomorphic adenoma of the vulva: a review illustrated by a clinical case

The pleomorphic adenoma of the vulva is an extremely scarce diagnosis. This form of neoplasm is more frequently observed in other topographic sites of the human body. Treatment modalities largely derive from experiences with the pleomorphic adenoma located in these other sites. As a result of similarity with other tumors and scarcity of the neoplasm, the diagnosis of pleomorphic adenoma of the vulva is easily missed in daily routine practice. Recurrences of this neoplasm are frequently observed with an estimated incidence of malignant transformation of 25%. Addressing this previously mentioned issue, an extensive surgical excision and long-term follow-up is advocated. This report is illustrated by the case of a 66-year-old woman who was admitted to our hospital with a pleomorphic adenoma of the vulva, diagnosed by pathologic assessments following surgical excision. As a result of the rarity of this diagnosis, characteristics and treatment of extravulvar in addition to vulvar localizations of the pleomorphic adenoma are reviewed.

[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.

Mixed tumors of the vagina: an immunohistochemical study of 13 cases with emphasis on the cell of origin and potential aid in differential diagnosis

Mixed tumors of the vagina (MTsV) are rare benign neoplasms characterized by an admixture of well-differentiated epithelial cells and stromal-type cells in various proportions. In contrast to mixed tumors in other anatomic sites, the histogenesis of the vaginal tumors is unclear. We studied the immunohistochemical profile of 13 examples to explore their histogenesis and determine whether their immunohistochemical profile might be useful in the differential diagnosis. The panel of antibodies used and the number of cases studied were: AE1/3 (12), cytokeratin 7 (CK7) (13), cytokeratin 20 (CK20) (13), epithelial membrane antigen (EMA) (13), muscle actin (MA) (12), desmin (11), h-Caldesmon (13), CD10 (13), CD34 (11), CD99 (8), and S-100 (7). Eight out of 12 tumors were positive for AE1/3, 7/13 for CK7, 2/13 for CK20, and 6/13 for EMA. MA was positive in 11/12 mixed tumors, desmin in 10/11 tumors and h-Caldesmon in 5/13. All tumors were extensively positive for CD10; CD34 was positive in 7/11; and none out of eight tumors showed membranous CD99 staining. Focal S-100 immunoreactivity was seen in 1/7 tumors. These results show that MTsV coexpress epithelial and mesenchymal markers. The expression of muscle actin (usually extensive), and focal desmin and h-Caldesmon positivity suggests the presence of a smooth muscle or myoepithelial component; however, the S-100 negativity and diffuse CD10 expression argue against it. Positivity for muscle markers does not help distinguish MTsV from smooth muscle or skeletal muscle tumors. The frequent expression of CD10 negates its use in the differential diagnosis with endometrial stromal tumors, and the CD10 and CD34 expression suggests that mixed tumors may arise from a primitive pluripotential cell. MTsV are positive for h-Caldesmon and CD10, two markers that have been used in gynecologic pathology primarily to aid in establishing the smooth muscle or endometrial stromal phenotype of a neoplasm.

Cylindroma of the Breast of Skin Adnexal Type

Four cases of solitary cylindroma of the breast of skin adnexal type are described. The tumors were morphologically and immunophenotypically identical to their dermal counterparts. They arose in close proximity to the nipple, such as the retroareolar area of the breast and in intimate association with the lactiferous ducts, suggesting an origin from the latter structures. One case occurred in a woman with hereditary multiple cylindromatosis (Brooke-Spiegler syndrome). This is the second reported case of this hereditary syndrome with extracutaneous manifestations and the first case in which the breast is involved.

Salivary-type neoplasms of the breast and lung

Salivary-type tumors occur in multiple sites in the human body, likely related to a basic structural homology between exocrine glands in these different anatomic areas. This paper reviews these salivary gland tumor types in breast tissue and lung. Salivary-type tumors of both breast and lung are relatively uncommon in comparison to their salivary gland counterparts. This may be attributable in part to lack of familiarity with these tumors in extra-salivary sites, and in part to histologic overlap with other primary and metastatic tumor types. Recognition of these entities is improving as the clinical and pathologic features are better delineated, and tumors are more accurately classified. Prediction of malignant behavior is not always possible in these unusual sites. In some instances, such as adenoid cystic carcinoma, behavior is known to differ considerably from that of analogous primary salivary gland tumors and in other instances there are simply too few reported cases to allow for adequate prognostication. In fact, more recent papers discuss the need to consider a spectrum encompassing benign and malignant lesions, in both breast and lung. Of course, some entities show clear-cut evidence of malignancy with documented potential for metastasis, others show bland features and well-reported benign behavior, and the less well-defined entities reside between these two extremes. The molecular pathology of salivary gland tumors has been reasonably well investigated in that location; however; there are few molecular studies devoted to salivary-type tumors of the breast and lung. This represents a potential area for future growth in further clarifying these tumors and their behavior.

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.

Pleomorphic adenoma of the breast. A case report and distinction from mucinous carcinoma

Pleomorphic adenoma of the breast is a rare, benign tumor accounting for 68 cases in the literature. It is most commonly seen in postmenopausal women and is characterized by an admixture of epithelial and myoepithelial cells embedded in abundant myxomatous stroma. Its clinical and histologic appearance can be challenging and may lead to a misdiagnosis of invasive carcinoma. We report a case of mammary pleomorphic adenoma in an asymptomatic 59-year-old woman and briefly discuss its distinction from mucinous carcinoma through the use of special stains.

Ductal adenoma of the breast with chondromyxoid change

A case of ductal adenoma of the breast in a 66-year-old woman is reported. The lesion was a small, firm nodule present in the periareolar area of the left breast. It showed extensive hyalinization with tubular structures and spotty calcifications. In spite of such a regressive and relatively well-circumscript appearance, focal eccentric peripheral sclerosis with distorted ductal structures suggested malignancy. However, immunohistochemical examination demonstrated a preserved myoepithelial layer surrounding the ducts. The tumor also showed focal chondromyxoid change and adipocytic differentiation. The myxoid change started exclusively around the ductal structures within the hyalinized acellular stroma and coalesced to form larger chondromyxoid areas. Myoepithelial cells constituting the ductal elements may have been responsible for the aberrant mesenchymal differentiation of this tumor.

Immunolocalization of the smooth muscle-specific protein calponin in complex and mixed tumors of the mammary gland of the dog: assessment of the morphogenetic role of the myoepithelium

The immunohistochemical expression of the smooth muscle-specific protein calponin was studied to assess the contribution of myoepithelial cells to the histogenesis of spindle cells of complex and mixed tumors of the mammary gland of the dog and the origin of cartilage and bone in mixed tumors. Formalin-fixed tissues from 55 benign and malignant tumors (49 also containing surrounding normal mammary gland) were evaluated. Periacinar and periductal myoepithelial cells of all the 49 normal mammary glands were diffusely stained by the anti-human calponin monoclonal antibody. Calponin was found in 53 (98%) of the tumors studied, reacting with the myoepithelium-like cells of 86% of benign tumors and their remnants in 85% of malignant tumors. Five different types of calponin-immunoreactive myoepithelial cells were identified: hypertrophic myoepithelial cells. fusiform cells, stellate myoepithelial cells, rounded (myoepithelial) cells, and chondroblasts. Differences in staining intensity and staining pattern among these five types of cells suggested a transition of myoepithelial cells to chondroblasts. Stromal myofibroblasts also showed calponin immunoreactivity, but they did not react with a cytokeratin 14 monoclonal antibody, which recognizes myoepithelial cells in mammary gland. Calponin appears to be a very sensitive marker of normal and neoplastic myoepithelium in the canine mammary gland, and its identification in different cell types of complex and mixed tumors of the mammary gland of the dog suggests a major histogenetic role for myoepithelial cells.

Solitary cylindroma (dermal analog tumor) of the breast: a previously undescribed neoplasm at this site

The authors report a previously undescribed small, well-demarcated breast tumor similar to a dermal cylindroma in a 63-year-old woman. The tumor was an incidental finding in a lumpectomy specimen for infiltrating lobular carcinoma. The cylindroma was surrounded by normal-appearing breast parenchyma and had the typical "jigsaw" pattern of epithelial basaloid islands. The islands showed focal squamous and myoepithelial differentiation. A notable number of reactive dendritic Langerhans cells permeated the epithelial cell islands, a feature considered to be characteristic of dermal cylindroma. There was also ductal differentiation. Thick bands of hyaline periodic acid-Schiff (PAS) stain and collagen IV-positive basement membrane material bordered the cell islands, and PAS-collagen IV-positive hyaline globules were seen within the cell islands. There was no nuclear pleomorphism or mitotic figures. The cylindroma did not express gross cystic disease fluid protein 15, carcinoembryonic antigen, estrogen and progesterone receptors, or cytokeratin 20 (CK20). There was diffuse and strong immunoreactivity to CK AE1/AE3, and focal reactivity for CK7 and smooth muscle actin. Cylindroma of the breast should be distinguished from adenoid cystic carcinoma and basal cell carcinoma. Although clearly epithelial, the exact histogenesis and cell phenotype of this unusual dermal type cylindroma of the breast are unknown.

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

A tumor of the right breast was noticed in a 70 year old female. The tumor was round, 1 x 1 cm, and was encapsulated with thin fibrous tissue. The boundary was clear. The cut surface showed a mosaic pattern of brown and white dots and the texture was gritty. Histologically, glandular structures, trabecular or solid epithelial cell nests, myxoid, cartilaginous and osteoid areas, and one ossifying focus were found. Round, polyhedral or fusiform myoepithelial cells proliferated around the glandular structures and were dispersing into the myxoid and cartilaginous tissue. Myoepithelial proliferation was especially marked around the small glandular structure. Immunohistochemically, S-100 protein was strongly positive for the myoepithelial cells around the glandular structures and in the cartilaginous tissue. Until now, 54 cases of pleomorphic adenoma of the breast have been reported. In those cases, the subareolar region was a common site for the tumor, and pleomorphic adenoma was thought to arise from large ducts in this region. No Oriental patients have been reported in the literature.

Immunohistochemical distribution pattern of intermediate filament proteins and muscle actin in feline and human mammary carcinomas

Thirty-seven feline and 38 human spontaneous mammary gland carcinomas were studied immunohistochemically. Commercially available antibodies directed against high and low molecular weight keratins (RCK-102 and NCL-5D3), vimentin, desmin, glial fibrillary acidic protein (GFAP), neurofilament (NF) proteins and muscle actin (HHF35) were used in the avidin biotin peroxidase complex (ABC) technique on formalin-fixed paraffin wax-embedded tumour tissue samples. Healthy feline and human mammary gland tissue adjacent to the neoplasms was also examined. The distribution pattern of intermediate filament proteins and muscle actin was comparable in healthy mammary gland tissue of the two species: both RCK-102 and NCL-5D3 antibodies reacted with luminal epithelial cells of ducts and acini, but basal/myoepithelial cells were stained by RCK-102 exclusively. In addition, basal/myoepithelial cells expressed vimentin and muscle actin in both species, and GFAP was found in some feline basal/myoepithelial cells. No immunoreactivity to desmin and NF proteins was observed. Feline mammary gland carcinoma cells reacted with RCK-102 (89%), NCL-5D3 (62%), vimentin (76%) and GFAP (30%) antibodies, while human mammary gland carcinoma cells reacted with RCK-102 (95%), NCL-5D3 (100%) and vimentin (13%) antibodies. HHF35 immunoreactivity was observed in stromal cells only. These results indicate that mammary gland carcinomas of both species share a heterogeneous immunophenotype with respect to intermediate filament proteins, which adds to the list of known similarities between mammary gland carcinomas of both species.

Salivary duct carcinoma--a highly aggressive salivary gland tumour with overexpression of c-erbB-2

The clinicopathological and immunocytochemical features of nine cases of salivary duct carcinoma are described. This relatively rare tumour, which only recently has been widely recognized as a separate entity, is highly malignant and caused the death in eight of the patients. The tumour cells are arranged in cribriform and solid growth patterns, where the solid tumour nests frequently have comedo necrosis, and a fibrous, often sclerotic, stroma is present. The infiltrating desmoplasmic component and the diffuse invasive growth into adjacent adipose parotid tissue have similarities to ductal breast carcinoma. Immunocytochemical investigation of salivary duct carcinoma showed constant overexpression of c-erbB-2 as detected by membrane accentuation, and high proliferative activity as detected by nuclear positivity for MIB 1 (Ki-67). Changes in the expression of p53 and retinoblastoma gene product do not constitute a constant event in salivary duct carcinoma. A few of the tumours showed scattered cells with distinct nuclear positivity for both progesterone and oestrogen receptors. We emphasize that this highly malignant salivary gland tumour has a characteristic morphology, may not be as rare as previously considered, and that prompt and aggressive therapy is needed.

Adenomyoepithelioma of the breast: report of a case initially examined by fine-needle aspiration

This report describes the morphologic features of an adenomyoepithelioma of the breast that was first examined by fine-needle aspiration. On retrospective review of the cytology, the stromal elements of this adenomyoepithelioma showed extensive metachromasia on Diff-Quik stain, had elongated nuclei, and on Papanicolaou stain showed elongated, pale, wispy cytoplasm. Clusters of stromal cells were usually intimately associated with epithelial elements. While the main differential consideration, cystosarcoma phylloides, can show similar features, it may be possible to distinguish the two lesions in some instances.

Immunohistochemistry with keratin, vimentin, desmin, and alpha-smooth muscle actin monoclonal antibodies in canine mammary gland: benign mammary tumours and duct ectasias

Duct ectasias (n = 2) and different types of benign canine mammary tumours (n = 19) were studied immunohistochemically with monoclonal antibodies (MoAbs) directed against various human keratin types (K), alpha-smooth muscle actin, vimentin, and desmin. In the duct ectasias and in most tumours the epithelial structures revealed an inner and outer cell layer. The inner cell layer was characterized by labelling with K 7, 8, 18, 19 and mostly also with K 4 and/or K 10 MoAbs. The outer cell layer was almost invariably labelled by K 14, K 14 and 17, and a-smooth muscle actin MoAbs. The labelling patterns of both duct ectasias and tumours corresponded largely to the patterns observed in normal mammary gland tissue, although a more distinct heterogeneity was seen. Tumours histomorphologically assumed to be of a myoepithelial origin did not show immunohistochemical features of myoepithelial cells. The myoepithelial nature of the vast majority of spindle-shaped cells present in the adenomas of the complex type and in the fibroadenomas of the benign mixed type could not be confirmed immunohistochemically. These cells, however, unequivocally expressed vimentin, suggesting proliferation of stromal cells in these tumours, which in the fibroadenomas of the benign mixed type may show metaplasia to bone or cartilage. In the duct ectasias and in some tumours, a fraction of elongated stromal cells, probably representing myofibroblasts, was labelled with the alpha-smooth muscle actin MoAb.