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Mucoepidermoid carcinoma (MEC) and adenomyoepithelioma (AME) are uncommon neoplasms of the breast that are more commonly noted in the salivary glands. AMEs are benign tumours that are known to undergo malignant transformation. This report describes the first case of a MEC arising in AME in a woman in her 50s.

INTRODUCTION: Breast adenomyoepithelioma is a very uncommon tumor, which is generally considered to be benign, however malignant transformation has been reported. PRESENTATION OF CASE: We report two cases of two women with breast adenomyoepithelioma. CONCLUSION: Diagnosis of adenomyoepithelioma is challenging because tumor may mimic other breast diseases. It has neither specific clinical signs nor radiological features, and the diagnosis is based on histopathological examination of the lesion. The treatment of choice is surgery. The type of surgery depends on the tumor factors and breast size. In malignant cases treatment such as radiotherapy, chemotherapy, immunotherapy may be used as well. It is very important to give an adequate treatment, otherwise the risk of tumor recurrence, growth or even metastatic spread, when tumor has malignant potential, increases.

Adenomyoepithelioma comprises a spectrum of lesions with variable morphology and clinical behavior, presenting at a wide age range. The most common presenting symptom is palpable abnormality. Mammographic abnormalities include focal asymmetries, masses and microcalcifications. Adenomyoepithelioma is a biphasic neoplasm characterized by proliferation of epithelial and myoepithelial cells. Adenomyoepitheliomas can be benign, atypical and malignant (adenomyoepithelioma with carcinoma). Malignant transformation occurs in either one or both cellular components leading to the development of invasive carcinoma. Invasive carcinoma types include invasive breast carcinoma of no special type, invasive lobular carcinoma, invasive carcinoma of special types, myoepithelial carcinoma, metaplastic carcinoma and biphasic carcinoma such as epithelial-myoepithelial carcinoma. While the majority of classic adenomyoepitheliomas have a benign clinical course and can be treated by local excision, local recurrence and distant metastasis have been reported. In malignant cases, treatment is determined by the associated carcinoma to include radiotherapy after breast conserving surgery and sentinel lymph node biopsy or axillary lymph node dissection, as indicated. Herein we report a case of a 62 year old woman who was found to have focal asymmetry on screening mammogram. She underwent a core biopsy of the lesion which showed atypical epithelial-myoepithelial neoplasm and excision was recommended. Upon excision, a diagnosis of malignant adenomyoepithelioma with associated epithelial-myoepithelial carcinoma was rendered with negative margins. The patient declined additional surgery for sentinel lymph node biopsy and declined adjuvant therapy. Six months after surgery, the patient is doing well with no complains. A follow-up mammogram and ultrasound of the axilla showed no abnormalities.

Adenomyoepithelioma (AME) of the breast is a rare tumor that is composed of proliferating epithelial and myoepithelial cells. The pathogenesis of AME remains unclear, and no breast cancer cells have been identified in such tumor tissues. In this study, we established patient-derived breast cancer organoids from the surgical tumor samples of an elderly Chinese woman with an AME of the breast. Our findings confirmed the successful establishment of organoids from an AME of the breast of this patient. A short tandem repeat analysis revealed that the DNA signature of the AME of the breast organoids matched the DNA signature of the original tumor specimen. Moreover, diameter assay confirmed that the organoids from the breast AME showed sensitivity to paclitaxel and doxorubicin treatments, which was similar to, but lesser than that of primary culture cells. In conclusion, we established an efficient 3-dimensional breast cancer organoid culture platform from an AME of the breast. This platform can be effectively used for exploring clinicopathological and genomic characteristics of AME of the breast to identify possible treatments and increase awareness about this disease entity.

乳腺恶性腺肌上皮瘤（malignant adenomyoepithelioma，M-AME）是一种罕见的乳腺上皮肌上皮双相分化肿瘤，形态学变化多样。本文报道2例M-AME，对其临床资料、组织学形态、免疫表型及分子特征进行分析，并复习相关文献，以提高在临床诊疗过程中对该疾病的认识。.

Triple-negative breast carcinomas constitute a wide spectrum of lesions, mostly being highly aggressive. Nevertheless, some special histologic subtypes can have low malignant potential. The purpose of the present paper is to review diagnostic criteria and prognostic parameters of breast neoplasms of special histotypes. Specifically, adenoid cystic carcinoma, adenomyoepithelioma, acinic cell carcinoma, mucoepidermoid carcinoma, tall cell carcinoma with reverse polarity, and secretory carcinoma will be discussed. For each tumour, definition and morphological and molecular features, together with prognostic parameters, will be presented. Paradigmatic cases will be illustrated.

Background Adenomyoepithelioma (AME) of the breast is a rare subtype of breast tumor. Most of AMEs reported are solid, however, cystic or prominent cystic changes are extremely rare. Case presentation A 51-year-old woman presented a lump in the upper outer quadrant of right breast, and it was accompanied by continuous breast pain and bilateral axillary itching for more than 2 months. There were no other symptoms found. Preoperative mammography and ultrasound examination were performed. Mammography showed a noncalcified lobulated mass, and it was considered to be a benign cyst with septum on ultrasound, but ductal carcinoma of breast, adenoid cystic carcinoma could not be excluded. At first, AME was not considered preoperatively, because the imaging features of this rare tumor may vary widely, which may result in an incorrect diagnosis. But eventually, AME was diagnosed by postoperative pathology and immunohistochemistry. Conclusion We herein present a rare case of breast AME with prominent cystic changes. AME has no-specific imaging features, but the benign or malignant nature of the lesion might be suspected on imaging.

Breast lesions with a prominent myoepithelial cell component constitute a heterogeneous group of benign and malignant neoplastic proliferations. These lesions are often dual epithelial-myoepithelial, but may be purely myoepithelial cell in nature. Benign epithelial-myoepithelial lesions typically maintain the morphology and immunophenotype of the normal bilayer epithelial myoepithelial structures. However, the distinction between the two cell components is not always clear-cut in malignant lesions in which the histogenesis of myoepithelial cells remains uncertain. Neoplastic biphasic epithelial-myoepithelial lesions of the breast include adenomyoepithelioma (AME), pleomorphic adenoma and adenoid cystic carcinoma. Four histological patterns of classical AME have been described: tubular, lobulated, spindle-cell and adenosis variants. Overlapping patterns occur and some AMEs display an intraductal papillary pattern that may represent a fifth variant. AME can be benign or malignant. Classical AME may show atypical features, which are not sufficient for the diagnosis of malignancy (atypical AME). Atypical AME is recognised as a lesion of uncertain malignant potential with limited metastatic capability. Based on the histological features, we propose a classification of malignant AME (M-AME) into three variants: M-AME in situ, M-AME invasive and AME with invasive carcinoma. In this review, we provide an overview of myoepithelial lesions of the breast focusing on the classification of AME to improve not only the consistency of reporting but also help to guide further management decision-making.

Background Adenomyoepithelioma of the breast is an uncommon subtype of breast neoplasm that occurs in adults over a wide age range but most commonly in middle-aged and older adults. It usually presents as a solitary palpable mass or is detected on breast radiographic images. Histologically, it is a biphasic tumor with proliferation of both the epithelial and myoepithelial components of the glands, with variable types of tissue metaplasia. Case presentation A 64-year-old Saudi woman who underwent regular breast screening (mammogram) presented to our hospital following radiographic detection of a suspicious grouped microcalcification in the upper outer quadrant of her right breast on the mammogram. A wide local excision of the right breast lump was performed. Following histopathological examination of the breast lump, the final diagnosis was breast adenomyoepithelioma with mucoepidermoid/divergent differentiation, with no evidence of malignancy. About two years after the operation, a clinical follow-up conducted outside our hospital showed the development of ductal carcinoma in situ in the same breast. Conclusion Although the prognosis and the plan of treatment remains the same, our case highlights the complexities in making an accurate diagnosis between the various types of metaplasia within adenomyoepithelioma on one hand and the presence of mucoepidermoid differentiation in adenomyoepithelioma on the other.

Breast cancer is a vastly heterogeneous disease encompassing a panoply of special histological subtypes. Although rare breast tumors have largely not been investigated systematically in large scale genomics series, recent studies have shed light on the genetic underpinnings of special histologic subtypes of breast cancer. Genomic analyses of estrogen receptor-positive special histologic types of breast cancer have not resulted in the identification of novel pathognomonic genetic alterations in addition to the confirmation of the presence of CDH1 loss-of-function mutations in invasive lobular carcinomas. By contrast, the analyses of triple-negative breast cancers have demonstrated that low-grade triple-negative breast cancers categorically differ from the common forms of high-grade triple-negative disease biologically and phenotypically and are underpinned by specific fusion genes or hotspot mutations. A subset of low-grade triple-negative disease has been shown to harbor highly recurrent if not pathognomonic genetic alterations, such as ETV6-NTRK3 fusion gene in secretory carcinomas, the MYB-NFIB fusion gene, MYBL1 rearrangements or MYB gene amplification in adenoid cystic carcinomas, and HRAS Q61 hotspot mutations coupled with mutations in PI3K pathway genes in estrogen receptor-negative adenomyoepitheliomas. A subset of these pathognomonic genetic alterations (e.g., NTRK1/2/3 fusion genes) now constitute an FDA approved indication for the use of TRK inhibitors in the advanced/metastatic setting. These studies have also corroborated that salivary gland-like tumors of the breast, other than acinic cell carcinomas, harbor the repertoire of somatic genetic alterations detected in their salivary gland counterparts. Reassuringly, the systematic study of special histologic types of breast cancer utilizing state-of-the-art sequencing approaches, rather than rendering pathology obsolete, has actually strengthened the importance of breast cancer histologic typing and is providing additional ancillary markers for the diagnosis of these rare but fascinating entities.

The first genotype-phenotype relationship in breast pathology developed in 1994 with the discovery of the CDH1 gene. This finding eventually provided biological insight into the characteristic morphology of invasive lobular carcinoma. Subsequent investigative efforts have uncovered additional molecular alterations largely responsible for the histology of several breast neoplasms including secretory carcinoma, adenoid cystic carcinoma, tall cell carcinoma with reversed polarity, fibroepithelial lesions, and most recently, adenomyoepithelioma. Evaluation of the genomic landscape of other special types of breast cancer with distinctive growth patterns, such as invasive mucinous carcinoma, have yet to uncover recurring cytogenetic and/or molecular alterations. Despite the lack of a hallmark alteration in mucinous carcinoma, it is important to note the relative decrease in PIK3CA mutations compared with invasive carcinoma of no special type. In this review, we describe the clinical and pathologic features of breast tumors with recognized genotype-phenotype correlations and summarize the molecular alterations of mucinous carcinoma.

Aims: Breast adenomyoepitheliomas (AMEs) are uncommon tumours. Most oestrogen receptor (ER)-positive AMEs have mutations in phosphoinositide 3-kinase (PI3K) pathway genes, whereas ER-negative AMEs usually harbour concurrent mutations affecting the HRAS Q61 hotspot and PI3K pathway genes. Here, we sought to determine the sensitivity and specificity of RAS Q61R immunohistochemical (IHC) analysis for detection of HRAS Q61R mutations in AMEs. Methods and results: Twenty-six AMEs (14 ER-positive; 12 ER-negative) previously subjected to massively parallel sequencing (n=21) or Sanger sequencing (n=5) of the HRAS Q61 hotspot locus were included in this study. All AMEs were subjected to IHC analysis with a monoclonal (SP174) RAS Q61R-specific antibody, in addition to detailed histopathological analysis. Nine ER-negative AMEs harboured HRAS mutations, including Q61R (n=7) and Q61K (n=2) mutations. Five of seven (71%) AMEs with HRAS Q61R mutations were immunohistochemically positive, whereas none of the AMEs lacking HRAS Q61R mutations (n=17) were immunoreactive. RAS Q61R immunoreactivity was restricted to the myoepithelium in 80% (4/5) of cases, whereas one case showed immunoreactivity in both the epithelial component and the myoepithelial component. RAS Q61R immunohistochemically positive AMEs were associated with infiltrative borders (P&nbsp

Background Breast adenomyoepithelioma (AME) is rare. We sought to evaluate clinical characteristics, treatment, and outcomes of a contemporary patient cohort stratified by histology. Methods We queried health records containing “adenomyoepithelioma” between 2000 and 2018. Histology was confirmed with centralized review and classified into benign, atypical, and malignant. Clinical characteristics, demographics, treatment, and oncologic outcomes were compared. Results Our query yielded 24 patients with adenomyoethelioma. Histologic diagnosis was confirmed in 12 (benign n = 6, atypical n = 3, malignant n = 3). Excision (n = 11) was the usual initial treatment, with margin status available in 10 patients. Mean follow up was 44 months (range 1–138 months) with no local recurrence observed. Two patients with benign AME presented with concurrent contralateral breast cancer, and one with malignant AME died of metastatic AME. Conclusion Wide excision of atypical and malignant AME is recommended as local recurrence when excised completely was not observed. Given metastatic potential of malignant AME, multimodal therapy may be warranted.

As one of the most common target organs for hematogenous spread from diverse cancers, biopsy interpretation of lung tumors is complicated by the challenging question of primary versus metastatic and by frequent entrapment of native respiratory glands. Nevertheless, the literature dealing with this issue is surprisingly sparse and no single study has been devoted to this topic. We reviewed 47 surgical lung specimens of non-epithelial neoplasms (38 metastases, mainly from sarcomas and 9 primary lesions) for frequency and pattern of intralesional epithelial entrapment. Respiratory epithelium entrapment was noted in 23/47 (49%) cases (diffuse in 15 and peripheral in 8). Entrapped glands frequently showed prominent regenerative and reactive changes mimicking neoplastic glands. Based on cellularity of the mesenchymal component and the extent, distribution and shape of entrapped respiratory glands, four morphological patterns were recognized: paucicellular sclerosing low-grade neoplasms containing leaflet-like glands indistinguishable from adenofibroma and fibroepithelial hamartomas (n = 11), and biphasic cellular lesions mimicking adenomyoepithelioma (n = 1), biphasic synovial sarcoma (n = 2), and pleuropulmonary blastoma (n = 1). Only a single genuine pulmonary adenofibroma was identified. This study highlights frequent respiratory epithelium entrapment in diverse non-epithelial lung tumors, both primary and metastatic. Recognition of this finding and use of adjunct IHC combined with clinical history should help to avoid misinterpretation as primary pulmonary biphasic neoplasm or as harmless adenofibroma. The vast majority of morphologically defined lung adenofibromas represent adenofibroma-like variants of histogenetically diverse entities so that a diagnosis of adenofibroma should be rendered only very restrictively and then as a diagnosis by exclusion.

Background Malignant adenomyoepithelioma of the breast is a rare tumor and most of relevant literature consists of individual case reports. This study objective was designed to evaluate clinicopathological features and treatment outcomes of 15 cases of malignant adenomyoepithelioma at a single institute. Methods A retrospective medical record review was performed for 15 subjects confirmed with malignant adenomyoepithelioma upon postoperative pathological diagnosis at the Asan Medical Center from January 2008 to June 2018. Data regarding age at diagnosis, preoperative biopsy results, operation methods, the status of hormone receptors and HER2, and clinical outcomes were collected. Results All cases were female patients diagnosed at median age of 50 years. Preoperative core needle biopsy results showed that 40% of the cases (6 out of 15) were benign which was in discordance with the final malignant pathology report. Thirteen cases underwent wide excision with or without sentinel lymph node biopsy (SLNB) and 2 cases had total mastectomy with SLNB. Five of 11 cases (45.5%) were triple negative. Ten of 15 cases underwent postoperative radiation therapy, 3 cases underwent chemotherapy, and 5 cases underwent endocrine therapy. During median follow-up of 55 months, the 5-year overall survival rate was 87.5% and the 5-year disease free survival rate was 91.7%. Two lung metastases developed. One case showed local recurrence 3 years after surgery and radiotherapy and subsequently developed lung metastasis 1 year late. Another case developed lung metastasis one and a half years after surgery in combination with endocrine therapy and neoadjuvant chemotherapy. Conclusion Preoperative core needle biopsy showed inaccurate results for diagnosing malignant adenomyoepithelioma. Malignant adenomyoepithelioma has a high rate of triple negative subtype but has a relatively good prognosis although there is a risk of local and systemic recurrence.

BACKGROUND Breast adenomyoepithelioma is a rare benign breast tumor characterized by a biphasic proliferation of epithelial and myoepithelial cells with variable clinical and diagnostic features. Establishing the diagnosis, determining optimal therapy, and predicting outcome are problematic because of the rarity of this entity. There have been only 2 large series of adenomyoepitheliomas of the breast, reported by Tavassoli and Rosen, which included 27 and 18 patients, respectively. In this report, we present 3 cases of breast adenomyoepithelioma. CASE REPORT Herein, we report 3 cases of breast adenomyoepithelioma. The first case is of a 64-year-old woman who was found to have right breast microcalcification on a screening mammogram. The second case is of a 74-year-old woman who had a right breast mass. These 2 patients were managed by wide local excision. Postoperative microscopic examination revealed adenomyoepithelioma. The third case is of a 49-year-old woman with bilateral saline breast implants who presented with a left breast mass. A core needle biopsy was done and revealed adenomyoepithelioma associated with usual ductal hyperplasia and ductal carcinoma in situ. CONCLUSIONS Breast adenomyoepithelioma is a rare condition that can pose diagnostic challenges due to variable imaging presentations, necessitating percutaneous core biopsy for initial diagnosis. Correct diagnosis is usually possible only on excisional biopsy and confirmed by demonstrating the biphasic nature of the tumor by IHC. Clinical suspicion coupled with utilizing both radiological and histopathological facilities can aid in the accurate diagnosis and management. For the most part, they are considered to be benign, but they can locally recur.

Papillary lesions of the breast represent a heterogeneous group of lesions including benign papillomas, papillomas with focal epithelial atypia, fully fledged ductal carcinoma in situ (DCIS) or lobular neoplasia, papillary DCIS, encapsulated papillary carcinomas without or with invasion, solid papillary carcinomas, and invasive papillary carcinomas. A micropapillary pattern characterized by lack of fibrous stalks within the papillae is observed in micropapillary DCIS and invasive micropapillary carcinoma. In addition, a variety of other rare breast lesions reveals a papillary architecture such as tall cell carcinoma with reversed polarity (TCCRP) and mucinous cystadenocarcinoma, adenomyoepithelioma, and secretory carcinoma. In addition, benign lesions such as usual ductal hyperplasia, apocrine metaplasia, gynecomastia, and juvenile papillomatosis may show a papillary or micropapillary architecture. Fragments of a benign papilloma in a breast biopsy are considered a lesion of uncertain malignant potential (B3 in the European classification) and excision is mostly recommended. Although the knowledge about molecular pathology of papillary breast lesions has increased, there is not sufficient evidence for diagnostically useful molecular features, yet. The aim of this review is to provide an update on papillary and micropapillary lesions with emphasis on problematic areas for daily diagnostic work including biopsies. ispartof: VIRCHOWS ARCHIV vol:480 issue:1 pages:65-84 ispartof: location:Germany status: published

Malignant adenomyoepithelioma (AME) of the breast is an exceptionally rare form of breast cancer, with a significant metastatic potential. Chemotherapy has been used in the management of advanced AME patients, however the majority of treatments are not effective. Recent studies report recurrent mutations in the HRAS Q61 hotspot in small series of AMEs, but there are no preclinical or clinical data showing H-Ras protein as a potential therapeutic target in malignant AMEs. We performed targeted sequencing of tumours’ samples from new series of 13 AMEs, including 9 benign and 4 malignant forms. Samples from the breast tumour and the matched axillary metastasis of one malignant HRAS mutated AME were engrafted and two patient-derived xenografts (PDX) were established that reproduced the typical AME morphology. The metastasis-derived PDX was treated in vivo by different chemotherapies and a combination of MEK and BRAF inhibitors (trametinib and dabrafenib). All malignant AMEs presented a recurrent mutation in the HRAS G13R or G12S hotspot. Mutation of PIK3CA were found in both benign and malignant AMEs, while AKT1 mutations were restricted to benign AMEs. Treatment of the PDX by the MEK inhibitor trametinib, resulted in a marked anti-tumor activity, in contrast to the BRAF inhibitor and the different chemotherapies that were ineffective. Overall, these findings further expand on the genetic features of AMEs and suggest that patients carrying advanced HRAS-mutated AMEs could potentially be treated with MEK inhibitors.

Apocrine hidradenomas (AH) once believed to harbor myoepithelial cells are now considered pure epithelial neoplasms. They are categorized separately from adenomyoepitheliomas which consist of apocrine epithelial and myoepithelial components. Reports of myoepithelial tumors arising in AH have suggested a link between the 2. Our goal was to explore whether cases diagnosed on routine microscopy as AH harbored occult myoepithelial elements, which would be disclosed by an immunohistochemical evaluation. Twenty-nine such cases, derived from a teaching collection of one of the authors, formed the basis of the study. Clinical and demographic data were documented, and morphological details of the cases were recorded. A panel of immunohistochemistry (AE1AE3, CK8/18, epithelial membrane antigen, p63, S100 protein, glial fibrillary acid protein, calponin, alpha actin, and others), designed to identify myoepithelial cells, was used. The population consisted of 14 women and 15 men (mean age 55.8; range 26-82 years). The tumors, located on the head/neck (14), limbs (10), and trunk (5), were solid (2) and solid/cystic (27). They exhibited varied (often combined) cytological elements (clear, squamoid, polygonal, and mucinous cells). On immunohistochemistry, aggregates of myoepithelial cells were identified in 5 (17%) cases. Four were calponin+ and AE1AE3+; they occupied ≤30% of tumor volumes and exhibited fusiform cytomorphology. One was S100 protein+ and AE1AE3+; it occupied 70% of tumor volume and exhibited polygonal cytomorphology. The gradation in the volume of myoepithelial elements disclosed by immunohistochemistry in a subset of our cases suggests that AH and adenomyoepitheliomas exist on a biological continuum of adnexal neoplasia. The diagnostic categorization of lesions with dual elements requires further study, but we propose that the term adenomyoepithelioma be restricted to those in which myoepithelial cells constitute ≥25% of tumor volume.

Adenomyoepithelioma is an extremely rare primary cutaneous neoplasm. Although there is ample evidence on the existence of malignant adenomyoepithelioma in the breast, a malignant counterpart in the skin has not been documented. We report a primary cutaneous adenomyoepithelioma (pcAME) with malignant features arising from a spiradenoma in a 39-year-old female patient. The tumor was solid-cystic in appearance and entirely located in the subcutaneous tissue. Histologically, the tumor displayed foci of adenomatous changes and adenomyoepitheliomatous hyperplasia adjacent to a minute spiradenoma. Gradual increase of architectural complexity, cytologic atypia, mitotic activity, and infiltrative growth were observed in a significant portion of the neoplasm, indicative of transformation to adenomyoepithelioma and subsequently low- to high-grade salivary-type epithelial-myoepithelial carcinoma (EMCA). The intimate dual populations of ductal and myoepithelial cells were highlighted by a panel of immunohistochemical stains in all different components of the tumor. Molecular studies revealed a PIKCA3 mutation, a genetic aberration that has been documented in EMCA, particularly of breast origin. The current case documents for the first time a pcAME with malignant features arising from a spiradenoma and suggests adenomyoepithelioma ex spiradenoma as a possible tumorigenesis pathway of this rare cutaneous tumor.

Papillary lesions of the male breast (PLMB) are uncommon. To date, PLMB have been reported as individual case reports and in relatively small series. We reviewed cases of PLMB diagnosed at our medical center over a 19-year (2000-2019) period. A total of 117 cases were identified, with an age range of 7 months to 88 years. These cases included 3 of papillary ductal hyperplasia, 5 intraductal papillomas, 1 adenomyoepithelioma, 5 atypical papillomas (ie, papillomas with atypia), 51 papillary ductal carcinoma in situ, 14 encapsulated papillary carcinomas, 38 solid papillary carcinomas, and 8 invasive papillary carcinomas. Malignant papillary neoplasms, including invasive and noninvasive ones, had a mean size of 1.3 cm (range: 0.3 to 4.4 cm), and all were ER and HER2. Fifty-four percent (19/35) of carcinomas were treated with excision alone, 46% (16/35) underwent mastectomy, and 63% (22/35) had axillary lymph node sampling. Only one case had metastatic involvement of axillary lymph nodes. Of the cases with follow-up, no (0/8) invasive carcinoma showed distant metastasis or proved fatal, and no (0/23) noninvasive papillary carcinoma recurred. Two notable cases of PLMB were encountered: one of a 7-month-old boy with NF1 mutation and florid papillary hyperplasia, and another of a 57-year-old man with Klippel-Feil syndrome and bilateral solid papillary carcinoma, invasive and oligometastatic on one side and noninvasive on the other. On the basis of this study of PLMB cases, the largest to date, and review of literature, we conclude that PLMB span a broad clinicopathologic spectrum, and that both invasive and noninvasive papillary carcinomas have relatively good prognosis.

Adenomyoepitheliomas (AME) of the breast and epithelial-myoepithelial carcinomas (EMCs) of salivary gland are morphologically similar tumors defined by the presence of a biphasic population of ductal epithelial elements mixed with myoepithelial cells. We sought to explore the molecular profile of AMEs and determine whether they might also share the PLAG1, HMGA2, and HRAS alterations seen in EMCs. Tumor tissue from 19 AMEs was sequenced and analyzed using Ion AmpliSeq Cancer Hotspot Panel v2 covering ∼2800 COSMIC mutations across 50 cancer-related genes. Cases were additionally screened by FISH for PLAG1 and HMGA2 rearrangements. Of 19 AMEs (12 benign; 7 malignant), 2 cases failed the DNA extraction. Of the remaining 17 cases, 14 had at least one nonsynonymous mutation identified. The most common mutations were in PIK3CA (6/17) and AKT1 (5/17), which were mutually exclusive. Two tumors demonstrated mutations in APC, while 1 demonstrated an STK11 mutation. Mutations in ATM, EGFR, FGFR3 or GNAS were identified in 4 cases with concurrent AKT1 mutations. HRAS mutation co-occurring with PIK3CA mutation was noted in 1 case of ER-negative malignant AME. While 2 cases harbored alterations in HMGA2, none was positive for PLAG1 rearrangement. Our findings confirm that breast AMEs are genetically heterogeneous exhibiting recurrent mutually exclusive mutations of PIK3CA and AKT1 in a majority of cases. HRAS mutations co-occur with PIK3CA mutations in ER-negative AMEs and may possibly be linked to clinically aggressive behavior. We identified hotspot mutations in additional genes (APC, STK11, ATM, EGFR, FGFR3, and GNAS). We report the presence of HMGA2 alterations in 2/16 AMEs, supporting their relationship with EMC of salivary glands in at least a subset of cases. PIK3CA, AKT1 and HRAS may serve as potential actionable therapeutic targets in clinically aggressive AMEs.

Rationale: Adenomyoepithelioma (AME) is a rare biphasic tumor consisting of epithelial and Myoepithelial cell. Most of the AME is benign, and only a few will progress to malignancy, Here, we report a case of low-grade malignant adenomyoepithelioma, and review the related literature, in a bid to investigate its clinical and pathological features and thus, enhance our understanding of this tumor. Patient concerns: A 64-year-old woman visited our hospital with a 1-year history of a painless mass in her left breast. Physical examination revealed a palpable painless mass, measuring approximately 4.5 cm, in the left breast. Diagnosis: Histological examination confirmed the diagnosis of malignant adenomyoepithelioma Interventions: The patient underwent local excision of the mass, with frozen section analysis revealing ductal carcinoma in situ. Mastectomy and sentinel lymph node biopsy were then performed. Outcomes: We conducted a one-year follow-up, and relapse was not observed. Lessons: Treatment of AME remains controversial owing to the lack of high volume data and absence of prospective studies. Simple mastectomy is an acceptable treatment of this tumor.

Adenomyoepithelioma of the breast is a rare tumor consisting of both epithelial and myoepithelial cells. Malignant transformation of either cell line can occur. We describe the imaging features, clinical presentation, and management of seven cases of biopsy-proven adenomyoepithelioma at our institution.

Papillary neoplasms of the breast encompass a wide range of tumor types ranging from the benign intraductal papilloma to in situ and invasive papillary carcinomas. In this review, we considered each tumor entity listed under the Papillary Neoplasms category in the latest WHO Classification of Breast Tumors (5th edition), namely intraductal papilloma, papillary ductal carcinoma in situ, encapsulated papillary carcinoma, solid-papillary carcinoma, and invasive papillary carcinoma. We examined their pathological features, current issues pertaining to diagnosis and prognostication, as well as the latest molecular findings. We also briefly addressed adenomyoepithelioma and the newly included tall cell carcinoma with reversed polarity, highlighting areas where they overlap with papillary neoplasms.

Introduction: Breast adenomyoepithelioma (AME) is a rare tumor composed of myoepithelial cells and ductal or luminal cells. Most cases of AME are benign, but rare cases in which either or both cell types exhibited malignant features have been reported. Due to its rarity, no diagnostic criteria for malignancy have been established for AME. Patient concerns: A 64-year-old woman presented with a mass in her right breast. Fine-needle aspiration cytology and biopsy examinations revealed lesions composed of spindle-shaped cells and round epithelial cells. AME was suspected, and partial mastectomy was performed. Diagnosis: The tumor specimen showed AME, which mainly consisted of spindle-shaped myoepithelial cells with slight atypia, admixed with tubular luminal cells and small areas of atypical intraductal proliferative lesions. No apparent features of malignancy, such as necrosis or invasion, were seen in the myoepithelial cells or the luminal or intraductal component. However, the atypical intraductal component exhibited focal nuclear atypia, a cribriform pattern, and moderate to strong membranous human epidermal growth factor receptor 2 (HER2) immunoreactivity. HER2 amplification was detected in focal regions of the atypical intraductal component by fluorescence in situ hybridization (FISH), which resulted in a diagnosis of AME with ductal carcinoma in situ. Outcomes: The patient did not receive further therapy and was free from tumor recurrence at 23 months after the operation. Conclusion: HER2 FISH might be useful for evaluating suspected AME tumors for malignancy when an atypical ductal lesion that lacks definitive features of malignancy is encountered.

Clear cell hidradenoma (CCH) is an uncommon adnexal tumor usually arising from eccrine glands and commonly seen on the face and the upper extremities. CCH occurring in the breast is extremely rare. Herein we report a case of MAML2-rearranged CCH of breast with a papillary architecture closely mimicking intraductal papilloma, adenomyoepithelioma and low-grade mucoepidermoid carcinoma, thus representing a source of diagnostic confusion. An overview of salient histologic features and immunophenotypes to distinguish CCH and low-grade mucoepidermoid carcinoma is also integrated into the report.

We present the case of a 73-year-old woman with an epithelial-myoepithelial carcinoma of the left breast (ie, malignant adenomyoepithelioma). In both the initial needle core biopsy and in the subsequently performed lumpectomy, the tumor consisted of nests of neoplastic epithelium and myoepithelium with cytologic atypia, increased mitoses, and infiltrative growth into the surrounding tissue. Mutational analysis showed oncogenic driver mutations in HRAS and PIK3CA. In this article, we describe an epithelial-myoepithelial carcinoma of the breast with focal metaplastic differentiation, an extremely rare entity, and report the results of targeted next-generation sequencing. Our patient has not shown any evidence of recurrent or metastatic disease at 29 months follow-up.

Aims Adenomyoepithelioma (AME) and adenoid cystic carcinoma (ACC) of the breast have been noted to occur simultaneously, raising the possibility that AME may represent a related or precursor lesion to ACC. ACC frequently harbours genetic rearrangement of the MYB gene. We sought to clarify the relationship between AME and ACC by comparing their rates of MYB expression by IHC and MYB rearrangement by FISH. Methods and results IHC and FISH for MYB rearrangement were performed on paraffin-embedded sections of 11 breast ACCs, 11 non-breast ACCs and 11 breast-AMEs. Using FISH, five of eight (63%) interpretable breast ACCs demonstrated MYB gene rearrangement. Nine of 11 (81%) breast ACCs demonstrated MYB expression (range = 20-95%). Of the three FISH-negative breast ACCs, two were solid variant and demonstrated strong MYB expression by IHC. Of the 10 interpretable non-breast ACCs, six showed MYB rearrangement, all of which were conventional type. Nine of these 11 (81%) cases showed MYB immunoexpression (range = 10-90%), including three solid-variant cases which were negative by FISH. No MYB rearrangements were detected by FISH in 10 interpretable AMEs. However, three of 11 cases (27%) showed weak to moderate MYB expression by IHC (range = 10-40%). Conclusions Our results indicate that AMEs do not harbour MYB gene rearrangement. IHC for MYB may be helpful in diagnosing FISH-negative cases of ACC, particularly the diagnostically more difficult solid variants. However, weak to moderate MYB expression in a subset of AMEs highlights not only a potential diagnostic pitfall, but also shared pathophysiology with ACC worth investigating further at the genomic level.

Background Histopathological diagnosis is important for prognostication and choice of treatment in patients with cancer in the lung. Metastases to the lungs are common and need to be distinguished from primary lung cancer. Furthermore, cases with synchronous or metachronous primary lung cancers (although infrequent) are often handled differently than cases with lung cancer with intrapulmonary metastasis or relapse, respectively. In some cases, morphology and immunohistochemical staining is not sufficient for certain diagnosis. Methods The present study included six cases where molecular genetic analysis in form of pyrosequencing or targeted next-generation sequencing was of value for certain diagnosis of selected tumours in the lung. Results Two of the included cases were rare metastases to the lung; colorectal cancer with IHC profile consistent with primary lung cancer and malignant adenomyoepithelioma of the breast, respectively, where molecular genetic analysis was of aid for proving the relationship to the primary tumour. The other four cases were multiple lung adenocarcinomas where molecular genetic analysis was of aid to distinguish between intrapulmonary metastasis and synchronous tumour. Conclusions Comparison of molecular genetic profile may be an important tool for determination of relationship between tumours in some situations and should always be considered in unclear cases. Further studies on concordance and discordance of molecular genetic profiles between spatially or temporally different tumours with common origin may be helpful for improved diagnostics of pulmonary tumours.

Adenomyoepitheliomas (AMEs) of the breast are uncommon and span the morphologic spectrum of benign, atypical, in situ, and invasive forms. In exceptionally rare cases, these tumors metastasize to regional lymph nodes or distant sites. In the era of genomic characterization, data is limited regarding AMEs. The aim of this study was to provide insight into the molecular underpinnings of a spectrum of AMEs. Seven cases of AMEs of the breast (benign-1, atypical-2, in situ-1, invasive-3) were identified in our files. The seven samples were interrogated using the Oncomine Comprehensive Assay v3 (ThermoFisher). Two atypical AMEs and the malignant in situ AME harbored the same gain-of-function PIK3CA mutation. The malignant in situ AME also showed EGFR amplification, not described previously. Both a benign AME and a malignant invasive AME shared the same gain-of-function AKT1 variant. The benign AME also showed a GNAS mutation. Moreover, the same gain-of-function HRAS mutation was present in an atypical AME and a malignant invasive AME. We also identified co-occurring HRAS and PIK3CA mutations in an ER-positive atypical AME, which has not been previously described. No fusion drivers were detected. We describe the molecular characteristics of the spectrum of AME tumors of the breast, which harbor alterations in the PI3K/AKT pathway. Our findings are clinically relevant with respect to the current options of targeted therapy in the rare instances where malignant AME tumors of the breast progress.

Pneumocytic adenomyoepithelioma (PAM) was first described in 2007 and was included in the 2015 World Health Organization Classification of lung tumors as a variant of epithelial-myoepithelial tumor. This rare pulmonary neoplasm was reported to show both myoepithelial and duct-like components, with the latter exhibiting pneumocytic differentiation with TTF-1 expression. We present an index case and 6 additional retrospectively-identified cases of pulmonary tumors with prototypical features of PAM. However, with additional clinicoradiologic, histologic, immunohistochemical and cytogenetic data, we were able to reclassify them as myoepithelial neoplasms – both primary and metastatic – with entrapped exuberantly hyperplastic alveolar structures lined by TTF-1 positive pneumocytes. We reviewed the available literature related to PAM and myoepithelial tumors. Our cases suggest that the entity referred to as PAM represents interstitial growth of myoepithelial neoplasms enticing marked proliferation of entrapped pneumocytes rather than a distinct biphasic neoplasm with pneumocytic differentiation.

Rationale: Male adenomyoepithelioma of the breast with malignant features is a rare tumor with only one previous case reported in the literature over 25 years ago. Patient concerns: We report the case of a 63-year-old man admitted to our Oncology Institute with a painless tumor mass of 6 cm in the left breast with no additional regional lymph nodes. Ultrasound revealed a complex cystic tumor mass of 60 mm in the left breast, with both anechoic (cystic) and echogenic (solid) components, with ill-defined margin. Diagnoses: Extemporaneous assessment showed a solid (invasive) papillary intracystic carcinoma. Definitive pathology examination revealed the presence of a breast malignant adenomyoepithelioma. Interventions: Based on the extemporaneous assessment, wide tumor excision was performed. The tumor board decided to continue treatment with adjuvant anthracycline-based chemotherapy. Outcomes: After 6 years of follow-up, the patient is cancer-free. No chronic side effects were noted. Lessons: Because this pathology is extremely rare, no guidelines are available for its therapeutic approach. All decisions regarding patient management should be made by a multi-disciplinary team and can only be based on clinical experience and the few cases reported in female patients.

Breast adenomyoepithelioma (AME) is a rare tumor with the published literature mainly in the form of case reports. Thus, there is currently only limited published data to guide evidence-based management. We sought to use a large, contemporary US database to evaluate how these patients are managed and describe expected outcomes. The National Cancer Database was queried (2004-2013) for women with AME. Statistics included multivariable logistic regression, Kaplan-Meier analysis to evaluate overall survival (OS) and Cox proportional hazards modeling. Overall, 110 patients were analyzed. At diagnosis, the median age was 67 years and the median tumor size was 2.0 cm. All but four patients had node-negative disease. A majority (55%) of tumors were estrogen receptor negative, and only one was positive for HER2/neu. The most common surgical procedure was lumpectomy (60%); a minority (10.9%) of subjects underwent complete axillary nodal dissection, with one-quarter not undergoing pathologic nodal sampling. Chemotherapy, hormonal therapy, and radiotherapy were utilized in a minority of patients (26%, 8%, and 36%, respectively), and none were associated with OS. At median follow-up of 52 months, the 5-year OS for the entire population was 74.4%. Disease-related characteristics and practice patterns are described for AME, the largest study of this rare tumor to date. Resection is the most important aspect of management, and based on this dataset the low rate of nodal involvement suggests that in some cases nodal sampling could be safely omitted. Adjuvant therapy may be considered on a case-by-case basis. Taken together, these data provide valuable insight into a rare neoplasm that may better inform management of these patients.

Aim To investigate mammography and magnetic resonance imaging (MRI) manifestations of benign and malignant adenomyoepithelioma (AME), in order to improve our understanding of this disease. Materials and methods Thirteen patients (11 cases of benign AME and two cases of malignant AME) were included. All patients underwent preoperative mammography, and four underwent preoperative MRI examinations. Results Mammography revealed that 11 cases showed round, lobulate, or oval masses. One case was accompanied by calcification with blurred edges; the remaining 10 cases showed masses with clear or shaded borders. One case exhibited structurally distorted lesions, and another showed focal opacities. Among the four patients who also underwent preoperative MRI examinations, signals in the three benign cases were clearly enhanced homogeneously, and the dynamic enhancement curves were progressive. The one case of malignant AME showed an irregularly shaped mass with spiculate margins on the MRI images. The signals were homogeneously enhanced, and the dynamic enhancement curve was of the washout type. Conclusion AME usually exhibited oval or round masses with smooth edges and no calcification, and, in a portion of the cases, structurally distorted lesions or focal opacities. On different MRI sequences, AME usually showed homogeneous signal. The apparent diffusion coefficient value of malignant AME is relatively low.

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.

We herein described two cases of adenomyoepithelioma (AME) with carcinoma of the breast. Both of them were Japanese women, and they presented with a mass in their breast. Post-operative specimens revealed encapsulated and well-circumscribed tumors with local invasion, necrosis, cytological atypia, and a high mitotic rate. In immunohistochemistry, coincidentally with the loose adhesion pattern of myoepithelial cells in both cases, the intensities of E-cadherin and beta-catenin were much weaker in myoepithelial than luminal epithelial cells, with almost negative finding of beta-catenin in one case. We first found deletion of CDH1 and polysomy of CEP16 in myoepithelial cells by double color-fluorescence in situ hybridization. The two cases have been followed up for 5-8 years, and both remained free from local recurrence and distant metastases. We also presented an overview of 47 cases of AME with carcinoma in English-language literatures.

Breast adenomyoepithelioma is considered as an uncommon breast tumor. It is evaluated as a variant of intraductal papilloma. The treatment of choice is local resection with free margins. It is the first case of breast adenomyoepithelioma reported with conventional ultrasonography, elastography (both free-hand and acoustic radiation force impulse imaging), digital mammography, contrast-enhanced digital mammography, and pathology findings. A 35-year-old white woman presented with a painless lump of the left breast. Treatment was local resection with free margins. There has been no recurrence for 6 months. Although breast adenomyoepithelioma is an uncommon breast tumor, its awareness is imperative because the differential diagnosis from other breast tumors is quite extensive.

Malignant adenomyoepithelioma (MAME) of the breast is a rare lesion characterized by dual population of epithelial and myoepithelial cells which one or both components show malignant features. We report a case of MAME of the breast in a 46-year-old woman diagnosed by fine-needle aspiration with extensive review of the literature. Classification, clinical presentation, cyto-pathologic, and immunohistochemical features are described. This lesion showed both malignant components of epithelial and myoepithelial cells in cytology and histology. The malignancy was convincingly supported by high mitotic figures, pleomorphism, and invasion in tissue sections. This review of MAMEs showed that cyto-histologic diagnosis is difficult and should be supported by immunohistochemical study.

In recent years, next-generation sequencing (NGS) became widely used in molecular pathology. Comprehensive mutational profiling improved diagnosis and prognosis, as well as the identification of therapeutically relevant genetic alterations. However, the vast majority of studies analyzing tissue samples use DNA extracted from bulk tissue or only manually microdissected specimens. Laser-assisted microdissection offers the possibility of isolating morphologically defined small tissue compartments (like individual glands) or even of single cells for further molecular analysis. Even formalin-fixed paraffin-embedded (FFPE) tissue specimens can be used for laser-assisted microdissection. Combining these two innovative powerful methodological approaches provides invaluable insights into the genetic profile of any cell type and tissue compartment of interest, contributing to a better understanding of fundamental biological processes and disease-specific mechanisms.In this chapter, a detailed protocol is provided for microdissection of human mammary adenomyoepithelioma tissue specimens and subsequent targeted resequencing of a panel of cancer-related genes using IonTorrent/PGM technology.

Adenomyoepithelioma of the breast is a rare tumor characterized by epithelial−myoepithelial differentiation, whose genetic underpinning is largely unknown. Here we show through whole-exome and targeted massively parallel sequencing analysis that whilst estrogen receptor (ER)-positive adenomyoepitheliomas display PIK3CA or AKT1 activating mutations, ER-negative adenomyoepitheliomas harbor highly recurrent codon Q61 HRAS hotspot mutations, which co-occur with PIK3CA or PIK3R1 mutations. In two- and three-dimensional cell culture models, forced expression of HRASQ61R in non-malignant ER-negative breast epithelial cells with or without a PIK3CAH1047R somatic knock-in results in transformation and the acquisition of the cardinal features of adenomyoepitheliomas, including the expression of myoepithelial markers, a reduction in E-cadherin expression, and an increase in AKT signaling. Our results demonstrate that adenomyoepitheliomas are genetically heterogeneous, and qualify mutations in HRAS, a gene whose mutations are vanishingly rare in common-type breast cancers, as likely drivers of ER-negative adenomyoepitheliomas., Adenomyoepithelioma is a rare tumor of the breast with an unknown genetic basis. Here the authors perform a genomic analysis of adenomyoepitheliomas revealing that their repertoire of somatic mutations vary according to the estrogen receptor (ER) status, and that ER-negative tumors harbor recurrent mutations in HRAS and PI3K pathway genes.

Adenomyoepitheliomas of breast are rare tumors. We report for the first time a case of an adenomyoepithelioma of the breast with associated lobular neoplasia. A 53-year-old woman had an annual screening mammogram, which identified areas of asymmetry in her left breast at 4-5-o'clock position. Resection of the masses revealed a well-circumscribed, gray-white, firm discrete nodule (0.8 × 0.4 × 0.3 cm). The tumor was composed of both adenomyoepithelial cell hyperplasia and focal atypical lobular hyperplasia. The 2 cell populations had some overlapping histologic features. Immunohistochemical analysis demonstrated a biphasic proliferation with approximately equal parts of luminal epithelial cells with clear and rounded appearance and myoepithelial cells. The myoepithelial component of the proliferation expressed myosin, p63, CK5/6, S-100, and dimly expressed E-cadherin. The epithelial component of the proliferation strongly expressed E-cadherin. In the areas of atypical lobular hyperplasia, there was distinct loss E-cadherin expression. Awareness of this association is highly important to provide these patients adequate follow-up and treatment.

Objective: We analyzed smears by fine needle aspiration (FNA) from 37 cases that displayed numerous dissociated cells and correlated the results with histological findings. Study Design: Between 1996 and 2005, 1,583 patients underwent breast FNA and resection. Loss of cellular cohesion was observed in 37 of these cases. Results: From the cytological findings, we classified cases into 3 groups according to cell size and shape. Type A: numerous isolated spindle cells with a necrotic background. Four cases were classified into this group (3 cases of intraductal papilloma and 1 case of adenomyoepithelioma). Type B: lymphocytes and large isolated cells such as medullary carcinoma. Five cases were classified into this group [1 case of classic medullary carcinoma, 1 case of ductal carcinoma in situ (DCIS) and 3 cases of invasive carcinoma of no special type (NST)]. Type C: numerous uniform small round cells. Twenty-eight cases were classified into this group (2 cases of lobular carcinoma, 1 case of DCIS, 22 cases of invasive carcinoma NST, and 3 cases of solid papillary carcinoma). Conclusion: Numerous isolated cells are sometimes seen in both benign and malignant cytology.

Adenomyoepithelioma of the breast is an uncommon tumor characterized by dual differentiation into luminal cells and myoepithelial cells. A spectrum of histologic patterns is observed among these tumors and even in different areas of individual tumors. These lesions can be diagnostically challenging, especially when a core needle biopsy is performed, because of the heterogeneity of adenomyoepitheliomas. Recognition of the biphasic cellular elements and the characteristic overall architecture of the tumors in combination with immunohistochemistry are essential to establish the correct diagnosis. Although most tumors have a benign clinical course, local recurrences, malignant transformations, and distant metastases have been reported. All the reported malignant adenomyoepitheliomas with metastases have shown significant cytologic atypia and brisk mitotic rates. Therefore, adequate sampling of the tumor to identify these features is necessary. A complete excision with adequate margins would lower the chance of local recurrence or potential for metastasis.