adenomyoepithelioma ( ame ) of the breast is an uncommon tumor characterized by dual epithelial and smooth muscle differentiation of tumor cells . sarkar and lallenbach   were first described about various amounts of myoepiepithelial cells with the degree of differentiation of various breast tumors in 1966 . hamperl   was first reported to ame of the breast in 1970 . according to many reports up to the present , it can demonstrate pure myoepithelial or epi - myoepithelial differentiation of benign and malignant breast tumors [ 1 - 3 ] . however , malignant transformation of tumor is characterized by infiltrating tumor margins , atypical cytologic change , brisk of mitotic figures , tumor necrosis and rarely can be distantly metastasized . according to world health organization , myoepithelial lesions of the breast can be classified as myoepitheliosis , adenomyoepithelial adenosis , ame and malignant myoepithelioma ( table 1 ) . we report herein on a case of synchronous myoepithelial carcinoma arising in ame and invasive micropapillary carcinoma in both breasts . a 51-year - old woman presented a re - growing remnant mass in the lower central area of left breast , which had already been resected with a mammotome assisted biopsy 6 months ago . initially , the tumor was recognized as fibroepithelial tumor with fibromatosis . as time went by , the remnant mass started re - growing in the left breast and a newly developed solid mass in the upper outer quadrant of the right breast mammography showed a 0.9 cm sized spiculated , heterogenous nodule at lower central portion of the right breast ( fig . also a 1.0 cm sized lobulated , iso - density nodule at upper outer quadrant of the right breast was noticed ( fig . , irregular marginated and hypoechoic mass was located at the 5 o'clock direction of the left breast ( fig . 1c ) and a 0.9 cm sized multilobulated , heterogenous and hypoechoic mass at 9 o'clock direction of the right breast . breast conserving surgery with sentinel lymph node biopsy was performed for the left breast mass . at a same time , wide excision was executed for the right breast mass . clear resection margins and no evidence of tumor metastasis in the sentinel lymph node were found in the submitted specimens . myoepithelial carcinoma and invasive micropapillary carcinoma were found in the left and right breast , respectively . grossly , the tumor mass from the left breast showed a relatively well - demarcated , multinodular , pale tan to white , and solid consistency with partially infiltrating margins . microscopically , the tumor from the left breast was composed of a central lesion with glandular epithelial lined spaces with increased clear changed myoepithelial cells and surrounding predominantly atypical spindle cells at the left lower corner ( fig . at the high power field of light microscopy , the atypical tumor cells showed round to spindle , hyperchromatic and pleomorphic nuclei with relatively abundant eosinophilic cytoplasm ( fig . atypical mitotic figures were easily found throughout the tumor and up to 8 mitoses were counted in 10 high - power fields ( fig . the right breast mass consisted of small clusters of tumor cells within the clear stromal spaces ( fig . the labeling index of ki-67 at the peripheral portion of mass was more than 40% . on the basis of the histological and immunohistochemical results , we considered this case as a synchronous myoepithelial carcinoma arising in ame and invasive micropapillary carcinoma in both breasts . ame of the breast is characterized by microscopically biphasic proliferation of epithelial and myoepithelial cells . the ame of breast is a very rare tumor that was already reported in 1970 . both benign and malignant ame are inclined to local recurrence after surgery and may even recur several years after the initial surgery . however we can use the term ' malignant ame ' that has infiltrating margins , markedly increased mitotic counts and distinctly cytologic atypia in case of not having definite metastasizing evidence . also distant metastasis and local recurrence subsequently , malignant transformation of ame can be divided into three different types according to the main malignant cell types : 1 ) completely epithelial type ; 2 ) malignant spindle cell type ; or 3 ) both epithelial and myoepithelial type . malignant epithelial carcinoma arising ame is similar to infiltrating ductal carcinoma , mucoepidermoid carcinoma or adenosquamous carcinoma . myoepithelial carcinoma or malignant myoepithelioma is purely composed of infiltrating myoepithelial cells with predominantly spindle features . microscopically , myoepithelial carcinoma shows infiltrating patterned spindle tumor cells with prominent cytologic atypia , increased mitotic activity ( more than 3 - 4/10 hpf ) and definitely infiltrating tumor borders . on immunohistochemistry , spindle tumor cells represent strong positivity of myoepithelial markers , such as smooth muscle actin , calponin , s-100 or p63 , and of epithelial markers , such as cytokeratin or epithelial membrane antigen . treatment of malignant ame or myoepithelial carcinoma has not been established yet except only complete surgical resection because of the rarity of this tumor . up to date , several cases of local recurrence or metastasis have been reported so myoepithelial carcinoma should be carefully examined and needed to close follow up . the differential diagnosis of myoepithelial carcinoma should be included spindle cell carcinoma , fibromatosis and variety of myofibroblastic tumors . the obviously atypical spindle cells which show positivity of myoepithelial and epithelial markers with infiltrating margins are helpful in distinguishing from the spindle cell carcinoma and myofibroblastic tumors . our case showed also biphasic pattern of immunohistochemistry of strong positivity for myoepithelial markers , such as smooth muscle actin , calponin , p63 , and for epithelial marker , such as pancytokeratin . also it demonstrated definite infiltrating tumor margins with high mitotic rates ( 4 - 5/10 hpf ) and prominent cytologic atypia . also there was a central lesion which showed biphasic proliferation of inner epithelilal and outer myoepithelial cells which could be diagnosed with ame . researched molecular abnormalities of malignant ame and reported the point mutation of p53 gene in this myoepithelial cells , but not in intraluminal epithelial cells or adjacent normal ductal epithelium . were performed comparative genomic hybridization ( cgh ) analysis on a malignant ame case in another study . have also reported that p53 protein was negative in benign myoepithelial lesions but overexpressed in 44.4% of malignant myoepithelial tumors of the breast . recently some molecular studies of ame have been trying to identify the molecular pathway of tumorigenesis of ame , but due to the rarity of ame or malignant ame , the pathway has not been established yet . in conclusion , our case is a rare case of myoepithelial carcinoma arising in ame with contralateral invasive micropapillary carcinoma . despite the definite diagnosis of malignant ame can be possible throughout various immunohistochemistry , pathologists who are unaware of myoepithelial lesions can make a misdiagnosis of malignant ame . finally , in case of malignant ame or malignant myoepithelial tumors , close follow up and in some cases , adequate further treatment with adjuvant chemotherapy or radiotherapy should be considered .
adenomyoepithelioma ( ame ) is a rare benign tumor composed of myoepithelial cells ( mecs ) which are located beneath the epithelial cells of exocrine glands , especially in breast and salivary glands . 
 these tumor cells show biphasic proliferation of epithelial and mecs . 
 malignant ame is characterized by distant metastasis , local recurrence , cytologic atypia , high mitotic activity and infiltrating tumor margins . a 51-year - old woman presented with an 8 months growth in the left breast 
 . she underwent core - needle biopsy and consecutively mammotome assisted biopsy at a local clinic . 
 after resection , she complained about re - growing remnant lesion and a newly developed solid mass in the right breast . 
 finally , the remnant mass in the left breast was diagnosed with myoepithelial carcinoma . 
 concurrently , contralateral breast mass was diagnosed with invasive micropapillary carcinoma . 
 herein we report an unusual case of synchronous myoepithelial carcinoma and invasive micropapillary carcinoma of the breast with a review of literatures .