Benign Adenomyoepithelioma Research Articles

Rare benign breast neoplasm masquerading as malignancy on anatomical and functional imaging with contrast-enhanced mammography

We discuss a unique case of a benign breast neoplasm that initially appeared to be an intracystic papillary carcinoma on digital breast tomosynthesis, ultrasound, and contrast-enhanced mammogram. However, subsequent histopathological examination (HPE) revealed it to be a benign adenomyoepithelioma, an uncommon neoplasm in the breast. Understanding this rare condition and confirming it pre-operatively through HPE can prevent unnecessary aggressive treatment.

Benign Adenomyoepithelioma: An Unrecognised Precursor of Ductal Carcinoma in Situ in Patient With Lynch Syndrome.

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.

Two resected cases of benign adenomyoepithelioma

BackgroundAdenomyoepithelioma (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 presentationWe 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.ConclusionsThe 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.

Benign Adenomyoepithelioma of the Breast: Imaging Characteristics.

This study aimed to evaluate the radiological and clinical characteristics of benign adenomyoepitheliomas of the breast. 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. 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. 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.

Benign adenomyoepithelioma of the breast: a case report

The diagnosis of adenomyoepitheliomas is difficult and relies on the presence of a double component of epithelial and myoepithelial cells belonging to the breast lobules and ducts. The clinical and imaging characteristics are not specific; thus, the diagnosis is histological. In this article, we present a case of a young female who presented with a 2 cm lump in the breast without other clinical symptoms, which revealed a benign adenomyoepithelioma (AME). We performed a large excisional lumpectomy, and the patient recovered well with no complication or recurrence within two years follow-up. When it comes to adenomyoepitheliomas, the published literature is mainly composed of case reports, so much so that there are no evidence-based guidelines. Our case shows that an excisional lumpectomy is often enough when facing a small size tumor with no signs of malignancy, which contributes to the limited data on the subject.

Malignant Biphasic Adenomyoepithelioma: A Rare Entity

Abstract Objectives Adenomyoepithelioma of the breast is an uncommon biphasic breast lesion characterized by a cytologically bland epithelial and myoepithelial proliferation. It is often considered benign and thought to represent a variant of intraductal papilloma. However, rare cases of adenomyoepitheliomas have been reported to show malignant transformation. Features that favor malignancy include increased mitoses, necrosis, atypia, cellular pleomorphism, and infiltrative borders. Most reported cases of malignant adenomyoepithelioma demonstrate carcinomas arising in a benign adenomyoepithelioma. Methods A 74-year-old woman presented to the hospital with an 8-month history of a palpable right breast mass. Mammogram demonstrated an irregular marginated mass, and a needle core biopsy of the mass showed atypical sclerosing adenosis. A lumpectomy revealed a firm, tan-white, ill-defined 2.7-cm mass abutting the anterior and posterior margins. Results Histologic examination showed an infiltrative proliferation of epithelial-lined tubules surrounded by myoepithelial cells with clear cytoplasm. There were focal areas of hypercellularity with marked cytologic atypia in both the epithelial and myoepithelial components. Focal necrosis and increased mitoses (12/10 HPF) were also identified. On immunohistochemical studies, the epithelial cells were positive for CK7 while the myoepithelial cells were highlighted by p63, SMMHC, SMA, and CK5/6. Ki-67 showed an increased proliferative index (35%). ER, PR, and HER-2 immunostains were negative. The overall histologic and immunohistochemical findings support a diagnosis of malignant biphasic adenomyoepithelioma. No in situ carcinoma was identified. After the diagnosis was reported, a follow-up reexcision with axillary sentinel lymph node excision was performed. Both specimens were negative for malignancy. Conclusion Malignant adenomyoepithelioma of the breast is an uncommon entity and it is strongly associated with local recurrence and distant metastases. Awareness of its distinctive histologic and immunohistochemical features will be helpful in initiating the appropriate medical management for patients with this entity, which is crucial for improving prognosis and overall survival.

Clinical characteristics and outcomes of benign, atypical, and malignant breast adenomyoepithelioma: a single institution's experience

BackgroundBreast adenomyoepithelioma (AME) is rare. We sought to evaluate clinical characteristics, treatment, and outcomes of a contemporary patient cohort stratified by histology. MethodsWe 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. ResultsOur 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. ConclusionWide 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.

Accurate diagnosis and sub categorization of benign adenomyoepithelioma of the breast-tubular type: A challenge on core needle biopsy

Accurate diagnosis and sub categorization of benign adenomyoepithelioma of the breast-tubular type: A challenge on core needle biopsy

Benign Bilateral Adenomyoepithelioma of the Mammary Gland in a Ring-tailed Lemur (Lemur catta)

Naturally occurring mammary tumours are uncommon in prosimians. A 20-year-old female ring-tailed lemur (Lemur catta) developed bilateral enlargement of the mammary glands. Surgical removal revealed that both masses were comprised of multiple nodules and cystic areas that entirely replaced the normal glands. Histologically, a benign neoplastic biphasic cellular proliferation, composed of luminal-epithelial and basal-myoepithelial components, was identified. Immunohistochemical analysis for expression of cytokeratin (CK) AE1/AE3, CK7, CK5+8, CK14, vimentin, p63 and 14-3-3σ highlighted the biphasic nature of the neoplasm. A low mitotic count, low Ki67 labelling index, expression of oestrogen receptor-α, lack of expression of human epidermal growth factor receptor and a 3-year disease-free period without recurrence supported the benign nature of the tumour. Macroscopically, histologically and immunohistochemically this neoplasm resembled benign adenomyoepithelioma of the breast in women. This is the first complete report of a naturally occurring mammary tumour in a ring-tailed lemur.

画像での経過観察ののち摘出した良性乳腺腺筋上皮腫の1例

症例は52歳，女性．右乳房腫瘤を自覚し，翌月の検診にて要精査となり当院を受診．右乳房9時方向に石灰化を含む2cm大の腫瘤を認め，DCISを疑って精査．MRIにて，右9時方向に区域性濃染がみられ，超音波でも血流と歪みの低下を伴う低エコー域であった．超音波ガイド下吸引式針生検では腺筋上皮腫（adenomyoepithelioma:以下AME）の診断であった．以後，経過観察していたところ，5年後に3.5cmまで増大したため，腫瘤切除術を施行した．術後病理は，乳頭状構築を呈し出血性嚢胞を伴うAMEで，悪性所見はなかった．AMEには，今回のように良性であっても増大するものや，悪性のものもあるため，診断後も注意深く経過観察を行う必要があると考えられた．

The mammography and MRI manifestations of adenomyoepithelioma of the breast

To investigate mammography and magnetic resonance imaging (MRI) manifestations of benign and malignant adenomyoepithelioma (AME), in order to improve our understanding of this disease. 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. 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. 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.

Imaging features of benign adenomyoepithelioma of the breast

The purpose of our study was to evaluate the imaging features of benign adenomyoepithelioma of the breast with a focus on sonographic (US) appearances. Ten benign adenomyoepitheliomas in 9 patients were included in this study. Mammographic and US findings were analyzed retrospectively by 2 radiologists according to the Breast Imaging-Reporting and Data System (BI-RADS) lexicon. The BI-RADS final assessment category was also recorded. Of the 8 lesions for which mammography was available, 4 lesions presented with abnormal findings. Two lesions presented with an indistinct, irregular, isodense mass and a circumscribed, oval, isodense mass. The other 2 lesions presented with areas of focal asymmetry and asymmetry, respectively. On US, all of 10 lesions presented as a mass. The masses measured 0.5-1.2 cm (mean, 0.8 cm), were irregular (n = 8) or oval (n = 2) with microlobulated (n = 5), indistinct (n = 3), or angular (n = 2) margins. They were all hypoechoic, had non parallel orientation in 6 cases, and increased peripheral vascularity in 7 cases. The BI-RADS final assessment category was 4B in 6, and 4A in 4. Mammographic findings of benign adenomyoepithelioma were nonspecific. An irregular, non parallel orientation, microlobulated or indistinct margin, hypoechogenicity, and increased peripheral vascularity were the most frequent US features.

Abstract P1-01-01: Fluorescence mapping with indocyanine green for sentinel lymph node detection in early breast cancer – results of the ICG-10 study

Abstract Background: Dual localization methods with blue dye and radioisotope are commonly employed for SLN identification but potential drawbacks include allergic reactions, radiation exposure and mandatory licencing. Identification rates exceeding 95% have been reported using the fluorescent tracer indocyanine green (ICG) as a navigation system. A feasibility study was undertaken to confirm the sensitivity and safety of ICG as a tracer agent for sentinel lymph node (SLN) identification in early breast cancer. Methods: In an open, non-randomised study, 100 clinically node negative patients (95 unilateral; 5 bilateral) scheduled to undergo routine SLN biopsy for core-biopsy proven invasive breast cancer were identified at the multidisciplinary team meeting [53 screen-detected; 51 symptomatic]. All patients received triple localization with blue dye (2.5% Patent Blue), radiocolloid and ICG (0.5%). The number of sentinel nodes for each patient were recorded numerically and whether blue, radioactive or fluorescent. Subcutaneous lymphatics were visualized with a Photodynamic Eye camera and sensitivity of individual tracers alone and in combination calculated. Approval was granted by the Local Research Ethics Committee and the Medicines and Healthcare Products Regulatory Agency for use of ICG as a third tracer agent. Results: Final analysis was performed on 104 procedures in 99 patients (1 exclusion - benign adenomyoepithelioma on definitive pathology). A total of 242 nodes were removed of which 201 were defined as sentinel (blue and/or radioactive) with an average nodal retrieval of 2.33 per procedure. Amongst these, 25 contained either macrometastases (n = 16) or micrometastases (n = 9), yielding procedural and node specific positivity rates of 17.3% (18/104) and 12.4% (25/201) respectively. 100% of these ‘true’ SLNs were fluorescent (201/201), 95.0% (191/201) were both fluorescent and blue, 77.6% (156/201) were fluorescent and radioactive whilst 73.1% (147/201) were blue, radioactive and fluorescent. The procedural detection rates were 99% (103/104) for blue dye, 91.3% (95/104) for radioisotope and 100% for fluorescence. All 25 positive nodes were identified with all three tracers and all 18 node positive patients had tumour deposits in the first SLN excised. The majority of ‘non-sentinel’ nodes were fluorescent (36/41) and no serious adverse reactions occurred. Conclusion: ICG fluorescence imaging permits real-time visualization of lymphatics and provides an additional dimension to SLN biopsy which is safe and effective. These results confirm high sensitivity for fluorescence in SLN identification and the combined nodal sensitivity for ICG and blue dye (95.0%) was higher than for blue dye and radioisotope (73.1%). With further refinements in the technique may it may be possible to eventually rely on ICG as a sole tracer agent. Moreover, a marginally higher nodal yield with fluorescent mapping may allow more confident omission of completion axillary dissection in selected SLN positive patients. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-01-01.

Malignant transformation of adenomyoepithelioma of the breast by a monophasic population: a report of two cases and review of literature

Two cases of adenomyoepithelioma of the breast with malignant transformation by monophasic population of cells are presented. The underlying benign adenomyoepithelioma with typical biphasic architectural pattern was identified and represented at least 30% of the tumor in each case. In both cases, malignant portion of tumor was composed of relatively uniform monophasic population of highly atypical cells. The malignant component in case 1 was positive for pan cytokeratin, myoepithelial markers, and basal-type cytokeratins and also focally positive for luminal-type of cytokeratins, but negative for hormone receptors (estrogen and progesterone) and HER-2/neu protein overexpression. The malignant component in case 2 was positive for spectrum of myoepithelial markers but negative for luminal cytokeratins, hormone receptors and HER-2/neu protein overexpression. The bilinear immunophenotype in the case 1 suggests that the malignant tumor may have developed from precursor multipotent cells that can differentiate into both luminal epithelial and myoepithelial cells, although malignant component in case 2 appears to be the of pure myoepithelial phenotype.

Myoepithilial tumours of the breast

Myoepithelial lesions of the breast are defined as lesions arising from or composed of a dominant pure population of myoepithelial cells. They include adenoid cystic carcinoma, pleomorphic adenoma, myoepitheliosis, adenomyoepithelial adenosis, adenomyoepithelioma and myoepithelioma. The last two can be benign or malignant. Myoepithelial tumours of the breast are extremely rare. The benign myoepitheliomas are composed of a solid proliferation of cells with abundant eosinophilic syncytial cytoplasm. Although the biological behaviour of these remains uncertain, the tumours are considered to be myoepitheliomas with benign features due to mild nuclear pleomorphism, sparse mitotic figures and low ki67 index. Malignant myoepitheliomas represent the malignant end of the spectrum of myoepithelial lesions in the breast, usually arising de novo or in a pre-existing benign adenomyoepithelioma. Myoepitheliomas most often have spindle cell morphology and may mimic benign and malignant lesions. We report two cases of myoepithelial tumours and present a review of the current literature. Case presentation: The two patients were females aged 60 and 85 years, respectively. One patient had a palpable breast lump and the other presented as a firm mass without palpable axillary lymph nodes. The diagnosis of the first case was myoepithelioma with uncertain biological behaviour since the mitotic rate was 3-4mf/10High Power Field (HPF), and the second a malignant myoepithelioma due to the high mitotic rate. Conclusion: The patients were treated surgically and remain alive, two years after the initial diagnosis.

Adenomyoepithelioma A Rare Breast Tumor: Case Studies With Review Of The Literature

Introduction : Adenomyoepithelioma is a rare, benign proliferative tumor that can involve the breast tissue. The diagnostic appearance of the lesion can give rise to a difficult differential diagnosis with breast carcinoma. There is the potential for malignant evolution of this lesion. It usually presents as a solitary, unilateral, painless mass at the periphery of the breast. Accurate diagnosis and differentiation from more aggressive tumors is important. Materials and methods :In two cases of breast lumps, fine needle aspiration cytology (FNAC) was done and stained with H & E and Papanicolaou stains. The formalin-fixed tissue sections were stained with hematoxylin and eosin and in one case, immunohistochemistry was performed with smooth muscle actin (SMA).Case 1: A 30-year-old female presented with a firm lump in the upper quadrant of the right breast along with axillary lymphadenopathy since 6 months. On ultrasound it was reported as duct ectasia. FNAC was suggestive of proliferative breast disease with atypia (possibility of duct cell carcinoma). Modified radical mastectomy was done and sent for histopathology. The histopathological diagnosis was adenomyoepithelioma – breast (right), tubular type.Case 2: A 25-year-old female presented with a firm lump in the left breast, occupying all quadrants. On FNAC the aspirates were suggestive of fibroadenoma. Peroperatively it was found to be a cystic swelling occupying the whole breast. The mass was excised and sent for histopathology. The histopathological diagnosis was adenomyeoepithelioma with apocrine metaplasia and cystic degeneration – breast (left), tubular type.Results : Two cases of breast lump were managed surgically. Both the cases were females with the mean age being 27 years. Both cases were of adenomyoepithelioma (tubular type) with one case showing apocrine metaplasia and cystic change. Conclusion : Prognosis of patients with benign adenomyoepithelioma of the breast is usually good, but it has a potential for local recurrence, especially in the tubular and lobulated variants. Total surgical excision with an adequate margin of uninvolved breast tissue is therefore recommended.

Fine‐needle aspiration biopsy of breast adenomyoepithelioma: A potential false positive pitfall and presence of intranuclear cytoplasmic inclusions

Cytologic diagnosis of adenomyoepithelioma can be very challenging. We report fine needle aspiration cytology (FNAC) findings of a benign adenomyoepithelioma. The cytologic features are characterized by hypercellularity and the presence of numerous atypical dispersed cells with epithelioid morphology and intact cytoplasm. The nuclei showed stippled chromatin, irregular nuclear membrane, and prominent eosinophilic nucleoli. No necrosis or mitoses were seen. The presence of naked nuclei, and extensive intranuclear cytoplasmic inclusions were identified and raised the possibility of adenomyoepithelioma. Immunohistochemically, the atypical cells showed strong positivity for myosin heavy chain, p63, and CK5/6, while the epithelial cells reacted with estrogen receptors. This immunophenotypic pattern supports the myoepithelial origin of the atypical cell proliferation and favors the diagnosis of benign adenomyoepithelioma. However, biopsy was recommended to exclude malignancy. Histologically, the tumor showed prominent myoepithelial cells with significant atypia, intranuclear cytoplasmic inclusions, and dense cytoplasm. No evidence of malignancy was identified. In conclusion, we report a case of adenomyoepithelioma with a significant cytological atypia that may result in confusion with malignant breast tumors. The presence of intranuclear cytoplasmic inclusions, naked nuclei, and expression of myoepithelial markers should provide clues to the right diagnosis and benign nature of this lesion. Cytopathologists should be familiarized with this entity to avoid a misdiagnosis of carcinoma.

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

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

Ultrasonographic Features of Benign Adenomyoepithelioma of the Breast

ObjectiveThe purpose of this study was to evaluate the ultrasonographic features of benign adenomyoepithelioma of the breast.Materials and MethodsBetween 2005 and 2009, five patients had histologically confirmed adenomyoepithelioma of the breast. We retrospectively evaluated the ultrasonographic findings of the tumors in correlation with the pathology, and reviewed medical records.ResultsThe clinical manifestations included a palpable mass in three patients, while mammographic screening helped detect abnormalities in two patients. Ultrasonograms showed masses with an oval (n = 3) or irregular (n = 2) shape, with uncircumscribed (n = 4) or relatively well-circumscribed (n = 1) margins, as well as with a hypoechoic (n = 3) or a complex echoic (n = 2) internal echo texture. Three patients had focal ductectasia adjacent to the mass. The ultrasonographic assessments were classified as Breast Imaging Reporting and Data System (BI-RADS) category 4A, with low suspicion of malignancy in two cases, and as category 4B, with intermediate suspicion of malignancy in three cases. The pathology revealed benign adenomyoepithelioma in all patients.ConclusionBenign adenomyoepitheliomas appear as solid or complex echoic masses with suspicious malignant ultrasonographic features, which may be associated with adjacent ductectasia. Although adenomyoepithelioma is a rare breast tumor, awareness of its sonographic features will be helpful for the differential diagnosis from other tumors.

Radioresistant malignant myoepithelioma of the breast with high level of ataxia telangiectasia mutated protein

Malignant myoepithelioma of the breast (MMB) is a rare and often aggressive disease with poor prognosis. Little is known regarding its optimal treatment and progression. We describe the clinical history of a woman following excision of a benign adenomyoepithelioma which recurred years later as a radioresistant malignant myoepithelioma with high levels of ataxia telangiectasia mutated protein and mutant p53 (Cys135Phe). MMB requires close follow-up and aggressive treatment. If adjuvant radiotherapy is adopted to improve local control, minimal postoperative delay and higher doses than for standard post-mastectomy radiation are recommended.