The role of immunohistochemistry for smooth-muscle actin, p63, CD10 and cytokeratin 14 in the differential diagnosis of papillary lesions of the breast

BACKGROUND: Histological differentiation of mammary papillary lesions can be difficult. The evaluation of myoepithelial cells can be helpful, with benign papilloma showing a continuous myoepithelial cell layer, which becomes attenuated or absent in malignant papillary lesions. METHODS: A large series of 100 papillomas (28 papillomas with florid epithelial hyperplasia) and 68 papillary carcinomas (9 invasive, 44 in situ, and 15 ductal carcinomas in situ (DCIS) involving papillomas) of the breast were stained for myoepithelial cells by immunohistochemistry using antibodies to smooth-muscle actin (SMA), p63, CD10 and cytokeratin (CK) 14. RESULTS: In the papillomas, using these four antibodies, myoepithelial cells were positive in 88%, 99%, 91% and 95% of cases, respectively, with SMA showing marked stromal component cell staining and CD10 showing epithelial and stromal staining. CK14 also showed epithelial staining in 71% of papillomas and 96% of papillomas with florid epithelial hyperplasia. In the papillary carcinomas, 36 (53%) cases showed staining of myoepithelial cells that were scattered, discontinuous and diminished in number and the remaining 32 (47%) cases did not show myoepithelial cells. Invasive papillary carcinoma has the lowest proportion (33%) with myoepithelial cells, and DCIS involving papillomas had the highest proportion (87%). CONCLUSIONS: p63 had the highest sensitivity and did not cross-react with stromal cells and only rarely with epithelial cells. CK14 has the added ability to distinguish between florid epithelial hyperplasia involving papilloma and DCIS involving papillomas. CK14 and p63 may be used as an adjunct in assessing difficult papillary lesions of the breast.     

乳腺导管内乳头状肿瘤187例临床病理及免疫组织化学特征

目的 探讨乳腺导管内乳头状肿瘤(IDPN)的诊断方法和标准.方法 收集187例IDPN患者的临床和病理资料,结合目前认可的2003年WHO乳腺和女性生殖系统肿瘤病理学和遗传学分类标准、Page等和Tavassoli的诊断标准,对其形态学特点进行分析,并对其中53例行CD10、p63、CK14、CK5/6、CK7、乳珠蛋白-1(MGB1)及p53免疫组织化学EnVision法染色分析.结果 187例IDPN患者中导管内乳头状瘤(IDPMa) 128例,不典型导管内乳头状瘤(A-IDPMa) 16例,导管内乳头状癌(IDPCa) 43例.IDPN在形态学上表现为不同程度的上皮细胞和间质增生,以及继发病变等,这些使病灶呈现异常复杂的多样性.免疫组织化学肌上皮标记(CD10和p63)染色在IDPMa、A-IDPMa及IDPCa的表达依次减少,组间比较差异均有统计学意义(均P＜0.001).基底型角蛋白(CK5/6和CK14)染色显示良性病变的表达呈镶嵌状阳性表达,在A-IDPMa的不典型区和IDPCa中表达明显减少或缺如,两者相比差异有统计学意义(P＜0.001).腺腔上皮标志物CK7染色各组间比较差异无统计学意义(P=0.06).MGB1在IDPCa组染色明显减少(P值分别为0.002和0.007),p53染色各组均呈阴性.结论 IDPN是一组组织学改变复杂的疾病,应注意其诊断标准的掌握.肌上皮、基底型角蛋白和腺腔上皮标志物联合应用在该组复杂病变中有很好的诊断和鉴别诊断价值.     

乳腺导管不同类型增生性病变中p63和 CK5/6的表达及意义

目的：明确不同类型的乳腺导管增生性病变中p63和Cytokeratin 5/6(CK5/6)的表达和意义。方法：对150例乳腺导管增生性病变中的368个病灶分别进行p63和CK5/6染色。结果：CK5/6在正常乳腺组织中的肌上皮和导管上皮均阳性表达，35例普通型增生中，33例CK5/6呈马赛克式阳性表达，仅2例弥漫阳性；在非典型性增生、原位癌和浸润癌中，CK5/6主要呈阴性表达，仅6例阳性，其中有2例雌激素受体（estrogen receptor, ER）、孕激素受体（progesterone receptor, PR）和CerbB 2阴性，符合基底细胞样癌的特点。p63在良性病变和非浸润性肿瘤性增生病变中的肌上皮细胞阳性表达，3例原位癌不表达p63和CK5/6。浸润癌中有3例（3/43）p63散在肿瘤细胞阳性，其余均阴性。结论：不同类型乳腺增生性病变中p63及CK5/6的染色模式存在一定规律，有助于这些病变的诊断和鉴别诊断。     

乳腺上皮-肌上皮性肿瘤4例临床病理学分析

目的：探讨乳腺上皮-肌上皮性肿瘤(epithelial-myoepithelial tumor of breast)的临床病理学特点、免疫表型、诊断及鉴别诊断。方法：对4例乳腺上皮-肌上皮性肿瘤的临床特点、组织形态学及免疫组织化学结果进行分析,并复习相关文献。结果：患者：男性1例,女性3例,平均年龄51岁(27~63岁)。4例肿瘤直径1.5~3.0 cm(平均2.0 cm),无包膜,切面灰白色。显微镜下可见肿瘤由双相增生的肌上皮细胞和腺上皮细胞构成,肌上皮细胞环绕腺上皮细胞构成特征的套管结构。免疫组织化学染色,腺上皮细胞表达CK8/18、CK7,肌上皮细胞表达p63、Calponin、CK5/6。1例诊断为腺肌上皮瘤(adenomyoepithelioma,AME),3例诊断为伴有癌的腺肌上皮瘤(恶性腺肌上皮瘤, malignant adenomyoepithelioma,MAME)。结论：乳腺上皮–肌上皮性肿瘤是少见的肿瘤类型,需与导管内乳头状瘤、化生性癌等鉴别。     

Immunohistochemical staining of papillary breast lesions.

The separation of ductal papilloma from intraductal papillary carcinoma of the breast on hematoxylin and eosin stained sections often presents diagnostic difficulty. Immunohistochemical staining is often employed in diagnosis, historically with smooth muscle actin (SMA). In this study, the staining characteristics of a panel of myoepithelial markers (calponin, p63, P-cadherin), were compared with SMA, and the epithelial expression of CD44s was assessed in 99 papillary lesions. SMA, calponin, and p63 demonstrated myoepithelial cells in 61%, 63%, and 65% of papillary lesions, respectively. However, specificity was quite variable. Calponin-stained stromal myofibroblasts (35% of cases), vessel pericytes (92%), and endothelial cells (69%), though each to a lesser degree than SMA. Calponin also showed cross reactivity with epithelium in 18% of cases. p63 was almost completely restricted to myoepithelial cell nuclei, and did not stain vascular smooth muscle or myofibroblasts. However, p63 stained the epithelial component in one papillary carcinoma, a basal layer of cells in 1 biphasic invasive carcinoma, and the cytoplasm in 1 case. P-cadherin stained both epithelial and myoepithelial cells. The epithelial expression of CD44s and did not distinguish papillomas from papillary carcinomas. Thus, P-cadherin and CD44s are not useful in the characterization of papillary lesions. Given increased specificity as compared with SMA, the combination of p63 and calponin is recommended for analysis of breast papillary lesions.     

Distribution of p63, cytokeratins 5/6 and cytokeratin 14 in 51 normal and 400 neoplastic human tissue samples using TARP-4 multi-tumor tissue microarray

p63, cytokeratin (CK) 5/6 and CK 14 have been employed in diagnostic pathology as markers of basal, squamous and myoepithelial differentiation in several types of human neoplasms; however, there is scant data on the concurrent expression of these markers in large series of human neoplasms. We analyzed the distribution of these three immunohistochemical markers in 51 normal human tissue samples, 350 carcinomas, 25 malignant melanomas (MMs), and 25 glioblastomas using three serial sections of tissue array research program (TARP)-4 multi-tumor tissue microarray. Also, we performed double immunostainings to characterize the differential distribution of p63/CK 5/6 and p63/CK 14 in normal breast, salivary gland and skin. p63, CK 5/6 and CK 14 were expressed in basal cells of the prostate and respiratory epithelia and in breast and bronchial myoepithelial cells. p63 was also expressed in cytotrophoblast cells of human placenta and in scattered cells of lymph node germinal center. CK 5/6 and CK 14 also stained the cytoplasm of basal cells of esophageal stratified squamous epithelium and transitional epithelial cells of the bladder. No mesenchymal, neural, endothelial, smooth muscle or adipose cells were stained by any of the markers. p63, CK 5/6, and CK 14 were respectively expressed in 92.6%, 75.0%, and 52.9% of the squamous cell carcinomas of the lung, 10.2%, 20.0%, and 7.4% of the ductal carcinomas of the breast, 12.9%, 34.4%, and 11.8% of the serous and 25.0%, 0%, and 0% of the endometrioid carcinomas of the ovary. Lung, prostate and colonic adenocarcinomas, as well as MMs and glioblastomas were only rarely decorated by one of the markers. Only matched samples of 16 squamous cell carcinomas and two ductal carcinomas of the breast co-expressed these three markers. In double immunostainings, p63-CK 5/6, as well as p63-CK 14 were co-expressed by basal/myoepithelial cells of the salivary glands and basal cells of the epidermis. Our results demonstrate that p63, CK 5/6 and CK 14 may be used together in immunohistochemical panels to characterize squamous differentiation in poorly differentiated carcinomas or carcinomas of unknown origin.     

Immunophenotypic characterization of anal gland carcinoma: loss of p63 and cytokeratin 5/6

Anal gland carcinoma (AGC) is a rare perianal invasive cancer composed of tubular glands lined by cuboidal epithelium. The clinical features and histogenesis of AGC are not well understood and its origin from anal glands is often difficult to prove. Little is known about immunophenotypic features of AGC that could be useful in establishing the diagnosis. This study evaluated the immunohistochemical profile of 2 cases of AGC in comparison to anal glands from 11 hemorrhoidectomy specimens. Sections from the specimens were routinely processed and immunostained using commercial antibodies to cytokeratin (CK) 7, CK20, CK5/ 6, p63, CDX2, smooth muscle actin, calponin, heavy chain smooth muscle myosin, p53, and p16. In case 1 of AGC, radiation and chemotherapy preceded an abdominoperineal resection. In biopsies from this case, the neoplastic anal glands had a tubular pattern, whereas most glands in the resection specimen exhibited mucinous features. The histologic pattern in case 2 was tubular. Normal anal glands showed immunoreactivity for myoepithelial and basal cell markers CK5/6 and p63 in basal and parabasal cell layers and for CK7 in superficial cell layers. In contrast, both cases of AGC were negative for CK5/6 and p63 and were diffusely positive for CK7. Normal glands and both cases of AGC were negative for the intestinal differentiation marker CDX2, CK20, smooth muscle actin, calponin, smooth muscle myosin heavy chain, p16, and p53. Our data suggest that loss of p63 and CK5/6 expression is a feature of AGC. Anal gland carcinoma shares negativity for CDX2 and CK7+/CK20- profile with normal anal glands. No evidence of myoepithelial cells was found in normal or malignant anal glands. These data may be useful in establishing the diagnosis of AGC.     

Assessment of invasion in breast lesions using antibodies to basement membrane components and myoepithelial cells.

This paper describes immunostaining of consecutive sections from 15 cases of fibrocystic change of the breast (including 2 examples of intraductal papilloma), 4 ductal carcinomas-in-situ and 17 invasive carcinomas (4 tubular, 1 papillary, 2 lobular and 10 infiltrating ductal, NOS) with antisera to components of the basement membrane (BM), type IV collagen and laminin, and with the muscle antibodies actin and muscle-specific actin. A simple digestion technique was developed to improve the clarity of BM staining with these antibodies. The BM stains facilitated identification of small invasive foci through breaks in the BM in 2 of the cases which had been reported as pure intraductal carcinoma. Tubular carcinomas were surrounded by abnormal, fragmented, and focally discontinuous BM, a feature which could be used to distinguish this well-differentiated breast carcinoma sub-type from sclerosing adenosis, in which individual acini were invariably surrounded by a continuous BM. BM staining emphasized the fibrovascular core of intraductal papillomas, whereas the BM layer was absent in intraductal, cytologically malignant, papillary projections. Similarly, myoepithelial cells, stained with antisera to muscle actins, were identified in a continuous layer surrounding benign epithelial proliferations. These immunohistochemical staining techniques may thus assist the diagnostic histopathologist in differentiating between benign epithelial proliferations of the breast and well-differentiated invasive breast carcinoma, and in identifying foci of microinvasive carcinoma.     

Double immunostaining with p63 and high-molecular-weight cytokeratins distinguishes borderline papillary lesions of the breast

Papillary breast lesions remain a source of diagnostic confusion because the full range of epithelial proliferations may arise within, or secondarily involve, papilloma. The expression of p63 and high-molecular-weight cytokeratins (HMWCK) was studied simultaneously in 33 papillary lesions including intraductal papilloma (IP, n = 10), atypical papilloma (AP, n = 8) and intraductal papillary carcinoma (IPC, n = 15) by double immunostaining. The myoepithelial cell nuclei were stained dark brown whereas the cytoplasms of usual ductal hyperplasia (UDH) and myoepithelium were stained purple. The myoepithelial layer was recognized as a dark brown dotted line at the epithelial stromal junction in all IP (10/10), most AP (7/8) and some IPC (7/15), suggesting that the retained myoepithelial layer in the papillary processes does not necessarily guarantee benignity. However, the malignant epithelial cells in AP and IPC were typically recognized as monotonous populations unstained with either chromogen. These monotonous cells contrasted with the proliferating cells of UDH in papilloma, which had intense purple cytoplasm in a mosaic-like fashion. The present data suggest that the double immunostaining with the two popular antibodies p63 and HMWCK is a useful tool for reproducible classification of papillary breast lesions.     

Diagnostic utility of p75 neurotrophin receptor (p75NTR) as a marker of breast myoepithelial cells.

We evaluated the low affinity neurotrophin receptor (p75NTR) as a marker of breast myoepithelial cells. Immunohistochemical staining for p75NTR was performed on paraffin sections of 122 malignant breast lesions, 28 benign lesions and the adjacent normal breast tissue. The staining pattern was compared to those of myosin heavy chain and p63. p75NTR immunostain was consistently positive and compatible with p63 and myosin immunoreactivity in the myoepithelial cells of the normal mammary gland, benign breast lesions (six usual ductal hyperplasias, six specimens with sclerosing adenosis, eight intraductal papillomas, six fibroadenomas), and carcinoma in situ (18 ductal carcinomas in situ, two noninvasive papillary carcinomas, two lobular carcinomas in situ). The luminal cells were negative for p75NTR, but rare positive cells were noticed in the solid areas of some of the usual ductal hyperplasias. Four of 64 invasive ductal carcinomas (6%) and all metaplastic carcinomas (n = 3, 100%) showed a variable degree of p75(NTR) positivity. No p75NTR expression was found in the malignant cells in all in situ carcinomas, invasive lobular carcinomas (n = 11), tubular carcinomas (n = 10), invasive papillary carcinomas (n = 6), mucinous carcinomas (n = 4), and medullary carcinomas (n = 2). No myosin immunoreactivity was seen in the luminal/tumor cells, but p63 pattern of staining in the luminal/tumor cells was quite similar to that of p75NTR. Although significant p75NTR immunoreactivity was noticed in the vessels, nerves, and stromal component of fibroadenomas, no difficulties in the evaluation of the immunostain of myoepithelial cells were encountered. Our study shows that p75NTR is a useful marker for breast myoepithelial cells and can be used to rule out invasive disease as well as to evaluate difficult for diagnosis sclerosing lesions. Our data suggest a role of neurotrophins in the development of fibroepithelial breast tumors and some of the breast carcinomas.     

Myoepithelial cell staining patterns of papillary breast lesions: from intraductal papillomas to invasive papillary carcinomas

We evaluated 25 intraductal papillomas and 18 papillary carcinomas (invasive, 4; micropapillary ductal carcinoma in situ [DCIS], 5; cases originally classified as intracystic/intraductal papillary carcinoma, 9) by calponin, smooth muscle myosin heavy chain (SMM-HC), and p63 immunostains. Calponin, SMM-HC, and p63 labeled myoepithelial cells (MECs) in all intraductal papillomas and all micropapillary DCIS cases. The invasive papillary carcinoma cases were uniformly negative for all stains. The 9 cases originally diagnosed as intracystic/intraductal papillary carcinoma showed more variable results, with identification of an MEC layer in only 4 cases. Comparison of staining of MECs by these 3 stains showed that calponin was more sensitive and intense than SMM-HC; however, there was cross-reactivity with myofibroblastic cells. Staining with p63 was discontinuous, making interpretation of an intact myoepithelial layer difficult. Of 9 cases originally classified as intraductal papillary carcinoma, 5 showed absence of a basal MEC layer by immunohistochemical analysis. The lack of a basal MEC layer in these cases suggests a spectrum of progression from in situ to invasive disease and might help explain distant metastases from previously reported "intraductal papillary carcinoma."     

Nested and microcystic variants of urothelial carcinoma displaying immunohistochemical features of basal‐like urothelial cells: An immunohistochemical and histopathogenetic study

Nested/microcystic (NV/MV) urothelial carcinoma (UC) variants are associated with mild cytologic atypia and commonly present at high‐stage disease. The histopathogenesis is investigated using urothelial basal cell markers. Archival 14 NV/MV and three inverted papilloma (IP) were immunostained for CD44, cytokeratin 5 (CK5), CK34bE12 and p63. Twenty consecutive cases of invasive high‐grade UC including 14 superficial and 6 muscle‐invasive UC cases were used as control. Immunostaining was scored as high for staining of full or more than 50% thickness of the epithelial nest or epithelium and low for lesser immunoreactivity and negative reactivity. All 14 NV/MV, 3 IP and 6 control cases showed a high score of immunoreactivity for CK5, CD44, CK34bE12 and focally for p63. The remaining control cases showed a high score of immunoreactivity for CK34bE12, while negative or low for CK5, CD44 and p63. In conclusion, immunoreactivity CK5 and CD44 commonly immunostained NV/MV and some invasive high grade UC. Other basal cell markers (CK34bE12 and p63) appear to be non specific or non sensitive. NV and MV and some UC likely represent a subset of UC displaying immunohistochemical features of urothelial basal cells. They had tendency of endophytic growth and early invasion despite the innocuous cytologic appearance.     

细胞角蛋白在乳腺导管内增生性病变鉴别诊断中的应用

目的 研究细胞角蛋白(CK)在乳腺导管内增生性病变的表达情况,寻求帮助乳腺导管内增生性病变鉴别诊断的分子标记。方法 按Page标准选病例,收集本院1993～2002年病理标本,乳腺导管内增生性病变92例(石蜡包埋标本)、冷冻切片30例以及导管上皮普通性增生原代培养上皮细胞和浸润性导管癌细胞株T-47D和MCF-7。采用EnVision标准二步法研究CK34βE12、CK8以及CK14表达情况。结果 (1)石蜡组织中CK34βE12在导管上皮普通性增生、不典型性增生、导管原位癌以及浸润性导管癌的阳性结果分别为95．2％、33．3％、19．2％和12．5％;导管上皮普通性增生、浸润性导管癌的冷冻切片CK34βE12阳性率为100％和55％;CK34βE12在MCF7呈阴性染色,在普通性增生原代培养细胞及T-47D中呈阳性染色;(2)CK8与CK14在乳腺导管上皮普通性增生的表达模式与其他病变不同。结论 CK34βE12有助于乳腺导管内增生性病变的鉴别诊断,但还不适用于术中冷冻快速诊断;CK8与CK14在乳腺导管内增生性病变中的表达模式可有助于鉴别诊断。     

Basal cell-specific and hyperproliferation-related keratins in human breast cancer.

In normal breast tissue and in noninvasive breast carcinomas, various keratin-14 antibodies were reactive predominantly with the basal/myoepithelial cell layer, although mainly in terminal and larger ducts luminal cells sometimes also were stained. A similar reaction pattern was found with an antibody directed against keratin 17, although this antibody was more often found negative than keratin 14 in the pre-existing myoepithelial cells in intraductal carcinomas. Furthermore antibodies reactive with hyperproliferation-related keratins 6 and 16 were used. One of these (LL025) was completely negative in normal breast tissue and noninvasive breast carcinomas. However 10% of the invasive carcinomas were diffusely or focally positive with this latter antibody, while in 18 of 115 cases of invasive breast carcinomas studied, a basal cell phenotype was detected. A relatively high concordance was found between the carcinomas immunostaining with the basal cell and the hyperproliferation-related keratins, but not between these markers and the proliferation marker Ki-67. This supports the conclusion that basal cells in breast cancer may show extensive proliferation, and that absence of Ki-67 staining does not mean that (tumor) cells are not proliferating.     

Distribution and significance of 14-3-3sigma, a novel myoepithelial marker, in normal, benign, and malignant breast tissue

14-3-3sigma is a candidate tumour suppressor gene transactivated by p53 in response to DNA damage. In gene expression analysis of normal luminal and myoepithelial cells, 14-3-3sigma was preferentially expressed by myoepithelial cells. This study has analysed the immunohistochemical distribution and subcellular localization of 14-3-3sigma in normal breast tissue and in a large series of benign and malignant breast lesions on whole tissue sections and by tissue microarray. Immunohistochemistry demonstrated that 14-3-3sigma was consistently expressed in the cytoplasmic compartment and occasionally in the nuclei of myoepithelial cells arranged as a continuous layer around normal ducts and lobular units, whereas luminal epithelial, stromal, endothelial, pericytic, lipomatous, and neural cells showed no staining. Myoepithelial cells of benign proliferations and pre-invasive lesions were consistently positive for 14-3-3sigma. Strong expression of 14-3-3sigma was evident in one case of ductal carcinoma in situ (5.5%) and in 105/554 invasive cancers (18.9%). Survival data were available for 452 patients with invasive breast carcinoma. 14-3-3sigma cytoplasmic subcellular localization was a statistically significant prognostic factor for the whole series of invasive carcinomas, as well as for those positive for oestrogen (ER) or progesterone receptors (PR). This analysis demonstrates the utility of 14-3-3sigma as a new adjunct antibody for characterization of myoepithelial cells and myoepithelial lesions and it may be a novel prognostic factor for breast cancer patients.     

Cytological criteria for the diagnosis of intraductal hyperplasia, ductal carcinoma in situ, and invasive carcinoma of the breast

The advent of mammography screening presents a diagnostic challenge to the cytopathologist as an increasing proportion of breast lesions requiring investigation will be nonpalpable and up to 40% will be accounted for by atypical intraductal hyperplasia and ductal carcinoma in situ, as opposed to previously, when these lesions represented less than 10% of palpable tumors. We studied 133 fine-needle aspirates from breast tumors and found that nuclear morphology, myoepithelial cells, signs of invasion, and degree of cellular dissociation are among the most potent factors discriminating between benign epithelial proliferations, atypical intraductal hyperplasia, ductal carcinoma in situ, and invasive carcinoma.     

Carcinoma ex pleomorphic adenoma (CXPA): immunoprofile of the cells involved in carcinomatous progression

AIMS: To characterize the cellular component in pleomorphic adenoma (PA) that undergoes malignant transformation in carcinoma ex pleomorphic adenoma (CXPA). METHODS AND RESULTS: A panel of antibodies against cytoskeletal proteins was applied in 16 cases of CXPA: intracapsular carcinoma (five cases), minimally invasive (four cases) and frankly invasive (seven cases). The CXPAs were classified into two main groups according to their predominant cellular component as detected by the panel of antibodies: (i) carcinomas with only epithelial differentiation (75% of the cases), and (ii) carcinomas with a myoepithelial component (25%). CXPA with only epithelial differentiation showed two types of malignant areas in the part of the tumour that was confined by the PA capsule: (i) intraductal carcinoma areas characterized by ductal structures containing both benign myoepithelial cells positive for alpha-smooth muscle actin (alpha-SMA), vimentin and cytokeratin (CK)14 and proliferating atypical luminal cells reactive for CK7, CK8 and CK19, and (ii) carcinoma areas composed only of epithelial cells reactive for CK7, CK8 and CK19. In the latter, the cells presented morphological and immunohistochemical characteristics similar to those found in areas of invasive carcinoma outside the PA capsule. CXPAs with a myoepithelial component were composed mainly or exclusively of cells that expressed vimentin and alpha-SMA. In this group, ductal structures reminiscent of PA filled by malignant cells were not identified. CONCLUSION: Most CXPAs consist only of epithelial cells that have an immunoprofile comparable to ductal luminal cells of PA. These malignant luminal cells arise in the duct-like structures as intraductal carcinoma and probably only at this early stage of development should the lesion be considered as a non-invasive carcinoma.     

Malignant adenomyoepithelioma of the breast combined with invasive lobular carcinoma

Presented herein is the first case of malignant adenomyoepithelioma (malignant AME) of the breast combined with invasive lobular carcinoma (ILC) in a 53-year-old woman. Histologically, the tumor was composed of nodular proliferation of biphasic epithelial and myoepithelial carcinoma, partially surrounded by ILC. Interestingly, ILC metastasized to the axillary lymph nodes, while biphasic epithelial and myoepithelial carcinoma hematogenously metastasized to the lung and the kidney. On immunohistochemistry the biphasic carcinoma consisted of cytokeratin (CK) 8/18-positive/CK5/6-positive/smooth muscle actin (SMA)-negative inner carcinoma cells and CK8/18-positive/CK5/6-positive/SMA-positive outer carcinoma cells. The monophasic ILC cells had a CK8/18-positive/CK5/6-negative/SMA-negative staining pattern. Although it is unclear whether both ILC and biphasic epithelial and myoepithelial carcinoma originated from AME or whether ILC occurred independently of malignant AME, this is an exceptionally rare case, which might give rise to a special consideration of the histogenesis of breast cancer.