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Objective: Myoepithelial carcinoma of the breast is an extremely rare malignancy. A study of all reported cases was undertaken to understand the behavior of this disease entity and the response to different treatment modalities. Data Sources: Databases, like Pubmed, Scopus, Web of Science, etc. were searched using the keywords myoepithelial carcinoma breast and adenomyoepithelial carcinoma breast from 1984-2022. A total of 1551 results were reviewed. Study Selection: Studies reporting a diagnosis of myoepithelial carcinoma on histopathology and immunohistochemistry were selected. Seventy-one cases of myoepithelial carcinoma of the breast were identified and found to be suitable for our review. The individual data of these cases and our patient were then compiled and evaluated. Results: The median age at presentation was 57 years, and there was no side preponderance. The average tumor size at presentation was 2.6 cm – most patients presented with a lump in the breast. Surgery remained the mainstay of treatment, with wide local excision and mastectomy performed in 50% and 30% of the patients, respectively. The benefits of radiotherapy and chemotherapy could not be ascertained, and most patients had a poor response to both. Of the patients in whom follow-up data were available, 28.3% and 13.1% were alive at 2 and 5 years, respectively. Locoregional recurrence was reported in 18 (25%) patients, and distant metastases were reported in 17 (23.6%) patients. Conclusion: Myoepithelial carcinoma of the breast is a rare and aggressive cancer. Surgery with negative margins is the primary treatment.

Currently, there is no robust evidence demonstrating a clear association between Lynch syndrome and non-malignant breast pathology such as adenomyoepithelioma. We report a case of benign breast adenomyoepithelioma, which after recurrence was associated with ductal carcinoma in-situ (DCIS) in a 41-year-old woman with Lynch syndrome, who lacked significant family history of breast or ovarian cancer. Both, the adenomyoepithelioma and DCIS were found to have nuclear loss of MSH2/MSH6 by immunohistochemistry, while germline testing confirmed MSH2 gene mutation. Concordant loss of MSH2 in both lesions in the context of a MSH2 pathogenic variant in this patient with Lynch syndrome illustrates that the benign adenomyoepithelioma behaved as a likely precursor of DCIS. Our report provides a novel perspective that in some patients with Lynch syndrome adenomyoepithelioma may represent a pre-malignant precursor lesion of DCIS. [ABSTRACT FROM AUTHOR]

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Objective: Myoepithelial carcinoma of the breast is an extremely rare malignancy. A study of all reported cases was undertaken to understand the behavior of this disease entity and the response to different treatment modalities. Data Sources: Databases, like Pubmed, Scopus, Web of Science, etc. were searched using the keywords myoepithelial carcinoma breast and adenomyoepithelial carcinoma breast from 1984-2022. A total of 1551 results were reviewed. Study Selection: Studies reporting a diagnosis of myoepithelial carcinoma on histopathology and immunohistochemistry were selected. Seventy-one cases of myoepithelial carcinoma of the breast were identified and found to be suitable for our review. The individual data of these cases and our patient were then compiled and evaluated. Results: The median age at presentation was 57 years, and there was no side preponderance. The average tumor size at presentation was 2.6 cm – most patients presented with a lump in the breast. Surgery remained the mainstay of treatment, with wide local excision and mastectomy performed in 50% and 30% of the patients, respectively. The benefits of radiotherapy and chemotherapy could not be ascertained, and most patients had a poor response to both. Of the patients in whom follow-up data were available, 28.3% and 13.1% were alive at 2 and 5 years, respectively. Locoregional recurrence was reported in 18 (25%) patients, and distant metastases were reported in 17 (23.6%) patients. Conclusion: Myoepithelial carcinoma of the breast is a rare and aggressive cancer. Surgery with negative margins is the primary treatment. [ABSTRACT FROM AUTHOR]

Abstract Background Adenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by the proliferation of ductal epithelial and myoepithelial cells with the heterogeneity. Although benign AME is relatively easy to differentiate from breast cancer by core needle biopsy (CNB) alone, a definitive diagnosis is often difficult. The imaging findings of AME are also variable, and there are particularly few reports about radiological features, including contrast-enhanced magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) values in AME. Case presentation We present two cases of benign AME. Case 1 is a 30-year-old woman with a history of asthma. The cystic tumor shows smooth borders, and the intracystic solid component is irregular in shape and high vascularity. The pathological findings of the tumor were benign on CNB. The MRI scan showed a decreased ADC value. Case 2 is a 60-year-old woman with only a history of arrhythmia. The tumor shows a lobulated mass with cystic space and coarse calcifications. The pathological findings of the tumor were found to be benign by CNB. Dynamic MRI scan showed a fast washout pattern with a decreased ADC value. Both patients underwent excisional biopsy to confirm the diagnosis, and the pathological diagnosis was benign AME in both cases. Conclusions The AME of the breast has little specific imaging information, so it can be difficult to diagnose based on pathological findings of biopsy specimen. In our case, the ADC values were exceptionally low, contrary to previous reports. It is essential to carefully diagnose AME, considering the discrepancies in imaging findings observed in this case.

Adenomyoepithelioma (AME) is a rare variant of breast neoplasm. It is a biphasic tumour characterized by small epithelial-lined spaces with inner luminal cells and outer of abluminal (myoepithelial) cells. Either -- or both -- of these two cells may rarely undergo malignant transformation. We present a case of a 61-year-old lady who arbored a mass in her right breast. She presented with few left sided pulmonary nodules as well and was initially diagnosed with extensive DCIS on core biopsy. Lung biopsy of nodule was diagnosed as epithelial myoepithelial neoplasm. Ultimately, modified radical mastectomy and pneumonectomy was performed. The final histopathological diagnosis turned out to be malignant. Adenomyoepithelioma with carcinoma; epithelial-myoepithelial carcinoma of breast with pulmonary metastasis. The malignant transformation of adenomyoepithelioma has been documented in only a limited number of cases. Benign AME often undergoes treatment through wide local excision, given its rare local recurrence. In contrast, the approach to malignant AME typically involves a mastectomy, with or without a lymph node biopsy. Metastases may manifest several years' post-primary diagnosis, even in cases of AMEs lacking atypical histological features. However, in our case metastasis was seen with in first four months of clinical presentation. Adenomyoepithelioma with carcinoma is an exceptionally rare neoplasm that may present with early metastasis, challenging the conventional findings of late metastasis as reported in studies. Consequently, the behaviour and prognosis of this entity remains a grey area, necessitating further exploration with a substantial sample size. [ABSTRACT FROM AUTHOR]

Background: Adenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by the proliferation of ductal epithelial and myoepithelial cells with the heterogeneity. Although benign AME is relatively easy to differentiate from breast cancer by core needle biopsy (CNB) alone, a definitive diagnosis is often difficult. The imaging findings of AME are also variable, and there are particularly few reports about radiological features, including contrast-enhanced magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) values in AME. Case presentation: We present two cases of benign AME. Case 1 is a 30-year-old woman with a history of asthma. The cystic tumor shows smooth borders, and the intracystic solid component is irregular in shape and high vascularity. The pathological findings of the tumor were benign on CNB. The MRI scan showed a decreased ADC value. Case 2 is a 60-year-old woman with only a history of arrhythmia. The tumor shows a lobulated mass with cystic space and coarse calcifications. The pathological findings of the tumor were found to be benign by CNB. Dynamic MRI scan showed a fast washout pattern with a decreased ADC value. Both patients underwent excisional biopsy to confirm the diagnosis, and the pathological diagnosis was benign AME in both cases. Conclusions: The AME of the breast has little specific imaging information, so it can be difficult to diagnose based on pathological findings of biopsy specimen. In our case, the ADC values were exceptionally low, contrary to previous reports. It is essential to carefully diagnose AME, considering the discrepancies in imaging findings observed in this case. [ABSTRACT FROM AUTHOR]

Adenomyoepithelioma represents a rare tumor of the breast characterized by biphasic proliferation of epithelial and myoepithelial cells. Owing to its nonspecific clinical presentation, the rarity, and the morphological pitfalls in differential diagnosis, the diagnosis may be extremely difficult especially on limited samples such as core needle biopsy; thus, the diagnosis is histological, which is confirmed by the specificities of the immunohistochemical analyses. Here we report a case of a 64-year-old female who presented a benign adenomyoepithelioma diagnosed on core needle biopsy, review the clinicopathological features of breast adenomyoepithelioma diagnosed on core needle biopsy, and discuss the useful clues to prompt accurate diagnosis. [ABSTRACT FROM AUTHOR]

Purpose This study aimed to evaluate the radiological and clinical characteristics of benign adenomyoepitheliomas of the breast. Materials and Methods Over the last 20 years, 120 patients were histologically diagnosed with breast adenomyoepithelioma (AME) at our institution. We excluded 43 patients who were incidentally diagnosed during mastectomy for breast cancer, 28 who underwent percutaneous biopsy without further excision, and 8 who had biopsy-confirmed benign AME and were found to have another pathology after complete excision. We retrospectively reviewed the clinical records and radiological findings of the remaining 41 patients with histologically diagnosed benign breast AMEs after complete excision. Results All 41 patients underwent US; 38 underwent mammography (MG) and US; and 18 underwent MG, US, and MRI. MG detected 38 cases with a round or oval shape (56%), and mass (89%), were non-circumscribed (62%), hyperdense (53%), and without microcalcifications (95%). Breast US revealed suspicious masses (98%) with a non-circumscribed margin (66%), hypoechogenicity (43%), and intratumoral vascularity (63%). All lesions on breast MRI showed suspicious masses (100%) with ill-defined margins (61%), and 84% showed wash-out kinetics. Benign AMEs showed suspicious features of Breast Imaging Reporting and Data System (BI-RADS) category 4 or 5 in 83%–95% of the MG, US, and MRI. Sixteen of the 41 cases were misdiagnosed on the initial core needle biopsy and two were diagnosed as malignancy. Conclusion Benign breast AME often shows suspicious radiological features mimicking a malignant mass on MG, US, and MRI. Differentiating benign AME from other pathologies might be difficult on core needle biopsy, and complete excision is needed for a correct diagnosis.

Abstract 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.

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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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract 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.