Best practices in diagnostic immunohistochemistry: myoepithelial markers in breast pathology

Tumour 63 protein (p63) in breast pathology: biology, immunohistochemistry, diagnostic applications, and pitfalls

Tumour protein 63 (p63) is a transcription factor of the p53 gene family, encoded by the TP63 gene located at chromosome 3q28, which regulates the activity of genes involved in growth and development of the ectoderm and derived tissues. p63 protein is normally expressed in the nuclei of the basal cell layer of glandular organs, including breast, in squamous epithelium and in urothelium. p63 immunohistochemical (IHC) staining has several applications in diagnostic breast pathology. It is commonly used to demonstrate myoepithelial cells at the epithelial stromal interface to differentiate benign and in situ lesions from invasive carcinoma and to characterize and classify papillary lesions including the distinction of breast intraduct papilloma from skin hidradenoma. p63 IHC is also used to identify and profile lesions showing myoepithelial cell and/or squamous differentiation, e.g. adenomyoepithelioma, salivary gland-like tumours including adenoid cystic carcinoma, and metaplastic breast carcinoma including low-grade adenosquamous carcinoma. This article reviews the applications of p63 IHC in diagnostic breast pathology and outlines a practical approach to the diagnosis and characterization of breast lesions through the identification of normal and abnormal p63 protein expression. The biology of p63, the range of available antibodies with emphasis on staining specificity and sensitivity, and pitfalls in interpretation are also discussed. The TP63 gene in humans, which shows a specific genomic structure, resulting in either TAp63 (p63) isoform or ΔNp63 (p40) isoform. As illustrated in the figure, both isoforms contain a DNA-binding domain (Orange box) and an oligomerization domain (Grey box). TAp63 contains an N-terminal transactivation (TA) domain (Green box), while ΔNp63 has an alternative terminus (Yellow box). Antibodies against conventional pan-p63 (TP63) bind to the DNA binding domain common to both isoforms (TAp63 and p40) and does not distinguish between them. Antibodies against TAp63 bind to the N-terminal TA domain, while antibodies specific to ΔNp63 (p40) bind to the alternative terminus. Each isoform has variant isotypes (α, β, γ, δ, and ε).

A case of giant nipple adenoma

BACKGROUND

Nipple adenoma is a relatively rare benign disease. Clinically, it often presents with nipple erosions, and it should be differentiated from Paget's disease.

CASE PRESENTATION

The patient was a 63-year-old woman who complained of a lump in her left nipple for more than 30 years. Computed tomography performed for screening congestive heart failure suggested a left nipple mass of 40 mm in size. Needle biopsy revealed nipple adenoma, and skin biopsy was also performed to confirm the diagnosis. Nipple tumor resection was performed under local anesthesia, and we confirmed that the final diagnosis was nipple adenoma with negative margins. The patient has been free from recurrence for 2 years since the surgery.

CONCLUSIONS

We have reported our experience of a case of giant nipple adenoma.

Immunohistochemical Staining Characteristics of Low-Grade Invasive Ductal Carcinoma Using the ADH5 Cocktail (CK5/14, P63, and CK7/18): A Potential Interpretative Pitfall

Background: In our practice, the antibody cocktail ADH5 (CK5/14, p63, and CK7/18) helps with diagnostic challenges, such as identifying microinvasion and foci of invasive carcinoma, differentiating atypical ductal hyperplasia from hyperplasia of the usual type, and distinguishing basal phenotypes in triple-negative carcinomas. However, the ADH5 cocktail does have pitfalls and caveats. Methods: We describe our experience with the ADH5 cocktail of antibodies in breast pathology. Institutional knowledge and a literature search form our data sources. Results: We analyzed 44 cases. Four out of a total of 44 cases (9.1%)-two tubular carcinomas and two low-grade invasive breast carcinomas of no special type (ductal) with tubular features-showed an expected pattern of staining for ADH5 with a loss of brown (P63, CK5/14) staining around invasive glands and diffuse red (CK7/18) expression. Forty out of 44 (90.9%) cases showed an unexpected staining pattern (mixture of cytoplasmic brown and red). All 44 cases (100%) showed negative myoepithelial staining around invasive foci when separately stained for P63 and SMMH (Smooth Muscle Myosin Heavy). Conclusions: The unexpected staining pattern of ADH5 in low-grade invasive ductal carcinomas can be challenging to interpret in these lesions with low-grade cytology. The occurrence can cause confusion among users who employ multiplex stains, and it is important for users to be aware of this potential pitfall.

Deciphering Stromal Changes between Metastatic and Non-metastatic Canine Mammary Carcinomas

Cancer-associated stroma (CAS) is widely recognized to influence development and progression of epithelial tumours including breast cancer. Canine mammary tumours (CMTs) such as simple canine mammary carcinomas represent valuable models for human breast cancer also with respect to stromal reprogramming. However, it remains unclear whether and how CAS changes in metastatic tumours compared to non-metastatic ones. To characterize stromal changes between metastatic and non-metastatic CMTs and identify potential drivers of tumour progression, we analysed CAS and matched normal stroma from 16 non-metastatic and 15 metastatic CMTs by RNA-sequencing of microdissected FFPE tissue. We identified 1438 differentially regulated genes between CAS and normal stroma, supporting previous results demonstrating stromal reprogramming in CMTs to be comparable with CAS in human breast cancer and validating deregulation of pathways and genes associated with CAS. Using primary human fibroblasts activated by treatment with TGFβ, we demonstrate some of the strongest expression changes to be conserved in fibroblasts across species. Furthermore, we identify 132 differentially expressed genes between CAS from metastatic and non-metastatic tumours, with strong changes in pathways including chemotaxis, regulation of apoptosis, immune response and TGFβ signalling and validate deregulation of several targets using RT-qPCR. Finally, we identify specific upregulation of COL6A5, F5, GALNT3, CIT and MMP11 in metastatic CAS, suggesting high stromal expression of these targets to be linked to malignancy and metastasis of CMTs. In summary, our data present a resource supporting further research into stromal changes of the mammary gland in relation to metastasis with implications for both canine and human mammary cancer.

DOG-1 as a Myoepithelial Marker in Discriminating Invasive Breast Carcinomas From Non-Invasive Breast Lesions

Introduction The most common cancer in women is, by far, breast cancer. The incidence and mortality of breast cancer must be reduced by a multidisciplinary strategy that includes education campaigns, preventive measures, screening programmes for early diagnosis, and the availability of treatment facilities. The use of immunohistochemical (IHC) stains with relative specificity for myoepithelial markers has become a mainstay of standard diagnostic breast pathology because the presence and distribution of myoepithelial cells might differ greatly amongst the distinct breast proliferation. Although it has also been reported that DOG1 is expressed in other mesenchymal tumours, DOG1 has been demonstrated to be sensitive and specific for the detection of gastrointestinal stromal tumors (GISTs). Both myoepithelial cells (MECs) and luminal epithelial cells have occasionally displayed DOG1 immunoreactivity in the breast. Materials and methods This prospective cross-sectional study was done in the Department of Pathology at Osmania General Hospital, Hyderabad on 60 cases from June 2017 to June 2019. Female patients with different breast lesions including benign proliferating lesions, ductal carcinoma in-situ (DCIS), and invasive carcinoma breast cases were included in the study. Inflammatory lesions, mesenchymal, and metastatic tumors were excluded. IHC expression of DOG1 as a myoepithelial marker to discriminate invasive from non-invasive breast lesions was evaluated and correlated with clinicopathological features. Results The mean age of the study population was 33.67 ± 8.48 in the benign group and 54.43 ± 12.84 in the malignant group. Fifty percent (15) of the patients with benign lesions belonged to the age group 20-30 years, whereas 26.7% (8) of the patients with malignant lesions belonged to the age group 61-70 years. DOG-1 expression was strongly positive in fibroadenoma, ductal hyperplasia, fibrocystic disease, whereas strongly negative in malignant disease of the breast (p < 0.0001). P63 expression was strongly positive in benign breast diseases and strongly negative in malignant diseases (p < 0.0001). Conclusion DOG1 seems to be similar to p63 as a myoepithelial cell marker both in normal breast tissue and in benign lesions. DOG1 is strongly positive in benign breast diseases and strongly negative in malignant breast diseases. Hence, it can be considered as a useful myoepithelial marker in differentiating invasive breast carcinoma and non-invasive breast lesions.

A Rat Experimental Model for Investigation of the Effect of Diabetes on Submandibular Salivary Glands Treated with Epidermal Growth Factor

Background: Despite the plethora of research around the negative effects of diabetes on different body organs, this topic still attracts a lot of attention in order to find potential remedies that could counteract or reverse the damaging effect of diabetes. Aim: In this study, we developed a reliable experimental rat model that can be used for investigation of the ability of epidermal growth factor (EFG) in restoring the normal architecture of oral tissues after being damaged by diabetes. Methods: Eighty adult male albino rats (average weight ±220 gm) were used in the current study. Twenty rats served as control and received no treatment. Diabetes was induced in forty rats using a single injection of 65mg/kg of Streptozotocin (STZ). Out of the forty diabetic rats, twenty rats received a single daily intraperitoneal injection of EGF (10 µg/Kg) for 8 weeks. Furthermore, twenty healthy rats received the same dose of EGF and served as positive controls. The submandibular salivary glands of all rats were examined for Immunohistochemical detection of myosin in the glandular structure. Results: The EGF treated group showed comparable myosin expression to the control group. The diabetic group revealed deterioration of all components of the submandibular salivary glands. Finally, the diabetic + EGF group has demonstrated restoration of the myosin expression levels in the submandibular salivary glands to a level that is not significantly different from healthy (non-diabetic) rats in the control group (p>0.05) and significantly higher than the diabetic group (p<0.0001). Conclusion: The findings of the present study confirm previous studies and validates the use of our animal model as predictable experimental tool to investigate the effects of diabetes and EGF on different oral tissues. It also highlights the importance of further research investigating EGF as a promising treatment modality for restoration of the condition and functions of tissues damaged by diabetes not only in the oral cavity but also around the whole body.  

Ductal Carcinoma in Situ: Molecular Changes Accompanying Disease Progression

Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive ductal carcinoma (IDC), whereby if left untreated, approximately 12% of patients develop invasive disease. The current standard of care is surgical removal of the lesion, to prevent potential progression, and radiotherapy to reduce risk of recurrence. There is substantial overtreatment of DCIS patients, considering not all DCIS lesions progress to invasive disease. Hence, there is a critical imperative to better predict which DCIS lesions are destined for poor outcome and which are not, allowing for tailored treatment. Active surveillance is currently being trialed as an alternative management practice, but this approach relies on accurately identifying cases that are at low risk of progression to invasive disease. Two DCIS-specific genomic profiling assays that attempt to distinguish low and high-risk patients have emerged, but imperfections in risk stratification coupled with a high price tag warrant the continued search for more robust and accessible prognostic biomarkers. This search has largely turned researchers toward the tumor microenvironment. Recent evidence suggests that a spectrum of cell types within the DCIS microenvironment are genetically and phenotypically altered compared to normal tissue and play critical roles in disease progression. Uncovering the molecular mechanisms contributing to DCIS progression has provided optimism for the search for well-validated prognostic biomarkers that can accurately predict the risk for a patient developing IDC. The discovery of such markers would modernize DCIS management and allow tailored treatment plans. This review will summarize the current literature regarding DCIS diagnosis, treatment, and pathology.

Conjunctival epithelial hyperplasia in a patient with a nodular lesion in the palpebral conjunctiva: A case report

The conjunctiva is a thin and delicate mucous membrane lining the inner eyelid and the anterior surface of the eyeball. Although hyperplastic changes can occur due to nonspecific chronic inflammation, ‘conjunctival epithelial hyperplasia’ has not been sufficiently established as a pathological entity. Additionally, the immunohistochemical (IHC) features of both the intact conjunctiva epithelium and conjunctival epithelial hyperplasia have not been sufficiently evaluated. The present report describes the case of an 86-year-old man who consulted with an ophthalmologist for a 6-month-old nodular lesion on his left eye. Located in the medial aspect of the left lower palpebral conjunctiva, the lesion was slightly erythematous and smooth. An excisional biopsy of the lesion was performed to obtain a pathological diagnosis. The hematoxylin and eosin sections revealed a thickened conjunctival epithelium composed of hyperplastic cuboidal epithelial cells and goblet cells, indicating conjunctival epithelial hyperplasia. Atypia, increased mitosis and a papillomatous architecture, indicative of neoplastic changes, were not observed. This resulted in conjunctival squamous intraepithelial neoplasia and squamous cell papilloma being ruled out. IHC analysis was performed to further characterize the lesion as well as the intact conjunctival epithelium. The thick conjunctival epithelium was composed of epithelial cells that stained positive for cytokeratin [AE1/AE3 (intensity: +), CK5/6 (intensity: ++), and CK7 (intensity: +)] and p63-positive basal cells (intensity: +) whose presence in the conjunctiva has received insufficient recognition. Moreover, squamous metaplasia was found in a segment of the thick conjunctiva, which exhibited IHC features similar to those of hyperplasia. CK5/6 was positive, indicating endogenous squamous differentiation of the conjunctival epithelial hyperplasia. These findings led to the diagnosis of conjunctival epithelial hyperplasia as a pathological entity. Further collection and analysis of several cases of conjunctival epithelial hyperplasia may lead the development of preventative methods and drug treatments for this lesion, and additional prognostic data, such as the recurrence rate.

Epithelial lacrimal gland tumors in dogs and cats: Is the human WHO classification appropriate for animals?

Lacrimal gland tumors (LGTs) in dogs and cats are rare neoplasms that can affect either the nictitans (NLG) or the main lacrimal gland (MLG). A consistent classification scheme for canine and feline LGTs is lacking; however, the importance of a classification scheme for LGTs has been emphasized in the human literature, and an update to the World Health Organization (WHO) classification has recently been published. The aim of this study was to investigate the occurrence of different subtypes of canine and feline LGTs in accordance with the human WHO classification system. Epithelial LGTs (n = 46 tumors; 38 dogs, 8 cats) were reviewed and immunophenotyping for p63, CK14, SMA, calponin, CKAE1/AE3, and CK19 was performed. Consistent with previous literature reports, lacrimal carcinomas outnumbered adenomas in dogs and cats. Based on the WHO classification of human LGTs, the most common subtypes identified in dogs were pleomorphic, ductal, adenoid cystic, and epithelial-myoepithelial carcinoma. In cats, a lower number of subtypes was observed, and adenocarcinoma "not otherwise specified" (NOS) was the most frequent diagnosis. An uncommon case of feline epithelial-myoepithelial carcinoma was also observed. The application of the human WHO-LGT classification scheme to canine and feline tumors increased the diversity of diagnoses and allowed for the identification of numerous subtypes. Further studies to identify possible correlations between pathological subtypes and prognosis are warranted.

Prognostic and predictive significance of tumor infiltrating lymphocytes for ductal carcinoma in situ

This study aims to identify the density of TILs in ductal carcinoma in situ (DCIS) in terms of prognostic significance with recurrence and the benefit of whole breast irradiation (WBI). The clinicopathological data of DCIS patients from Jan 2009 to Dec 2016 who received breast-conserving surgery (BCS) were retrospectively reviewed. Cox regression analysis was used to confirm independent prognostic factors of ipsilateral breast tumor recurrence (IBTR). Kaplan–Meier method was utilized to analyze IBTR and values of WBI. Touching-tumor-infiltrating lymphocytes (TILs) were defined by TILs touching or within one lymphocyte cell thickness from the malignant ducts’ basement membrane. In total, 129 patients were enrolled in this analysis with 98 patients who received WBI. After a median follow-up of 53.0 months, there were 16 IBTR events with five invasive IBTRs. Univariate and multivariate analyses showed that touching-TILs >5 were an independent prognostic factor for higher IBTR (HR = 6.17, 95%CI 1.95–19.56, p < .01). The whole cohort was classified into two subgroups: dense group (>5 touching-TILs per duct) and sparse group (≤5 touching-TILs per duct). Dense touching-TILs were associated with unfavorable biologic characteristics. The 5-y rate of IBTR between dense and sparse group was 29.0% versus 4.5% (p < .01). For the sparse group, WBI significantly reduced the rate of 5-y-IBTR risk from 13.2% to 1.7% (p = .02), but there was no benefit of WBI in the dense group. Touching-TILs density was heterogeneous in patients with DCIS. Sparse touching-TILs were associated with better prognosis and benefit from WBI. Dense touching-TILs not only were associated with a higher risk of IBTR but also lack of benefit from WBI.

Neural EGFL like 2 expressed in myoepithelial cells and suppressed breast cancer cell migration

Breast tissue has a branching structure that contains double-layered cells, consisting primarily of luminal epithelial cells inside and myoepithelial cells outside. Ductal carcinoma in situ (DCIS) still has myoepithelial cells surrounding the cancer cells. However, myoepithelial cells disappear in invasive ductal carcinoma. In this study, we detected expression of neural EGFL like (NELL) 2 and one of its receptors, roundabout guidance receptor (ROBO) 3, in myoepithelial and luminal epithelial cells (respectively) in normal breast tissue. NELL2 also was expressed in myoepithelial cells surrounding the non-cancerous intraductal proliferative lesions and DCIS. However, the expression level and proportion of NELL2-positive cells in DCIS were lower than those in normal and non-cancerous intraductal proliferative lesions. ROBO3 expression was decreased in invasive ductal carcinoma compared to that in normal and non-cancerous intraductal proliferative lesions. An evaluation of NELL2's function in breast cancer cell lines demonstrated that full-length NELL2 suppressed cell adhesion and migration in vitro. In contrast, the N-terminal domain of NELL2 increased cell adhesion in the early phase and migration in vitro in some breast cancer cells. These results suggested that full-length NELL2 protein, when expressed in myoepithelial cells, might serve as an inhibitor of breast cancer cell migration.

Expression of TdT in Myoepithelial Cells: Investigation in Breasts, Sweat Glands, and Salivary Lesions Emphasizing the Never-Documented Immunohistochemical Findings

Background. The expression of terminal deoxynucleotidyl transferase (TdT) in myoepithelial cells (MECs) within the breast was recently incidentally observed in our routine practice. This study aimed to elucidate the expression of TdT in MECs. Methods. TdT immunostaining was performed on 180 mammary, 89 cutaneous, and 94 salivary tissues or lesions. Other myoepithelial markers, including P63, calponin, and SMA as well as double staining for TdT and calponin, were also evaluated in some cases. Selected lesions with basal or myoid differentiation were also included in the investigation. Results. MECs were positive for TdT in mammary lesions that contained MECs (132/135) but negative when they did not contain MECs (45/45). MECs in sweat glands (24/30) and their neoplastic counterparts, including those in hidradenoma papilliferum (2/9), spiradenoma (6/6), and cutaneous mixed tumor (9/9), showed weak to moderate TdT positivity. MECs were variably immunolabeled for TdT in salivary or salivary gland-type tumors with myoepithelial differentiation (pleomorphic adenoma, 24/25; basal cell adenoma, 6/7; adenoid cystic carcinoma, 7/7; Warthin tumor, 0/6; mucoepidermoid carcinoma, 0/8; acinic cell carcinoma, 0/4), but MECs in normal salivary gland barely stained for TdT (30/32). Conclusions. Our findings indicate that TdT may be eligible as an additional auxiliary immunohistochemical marker as P63, but not a surrogate, to identify the MECs in the breast with limited cross-reactivity, particularly in lesions with a prominent proportion of MECs. Positivity for TdT, along with other relevant markers, in a subset of sweat gland lesions and salivary tumors may contribute to their diagnosis.

Benign breast papillary lesions diagnosed on core biopsy: upgrade rate and risk factors associated with malignancy on surgical excision

Evaluation of radiologically detected breast lesions is a common task in surgical pathology. Some benign lesions on biopsy are associated with an upgrade to in situ or invasive carcinoma on excision. The non-atypical breast papilloma has published upgrade rates of 0 to 29%. Traditionally, papillomas have been managed surgically, but the wide range of upgrade rates has raised uncertainty about the need for routine surgical excision. This study aims to identify risk factors associated with upgrade and determine the upgrade rate of non-atypical papillomas at our institution. In a retrospective review of pathology reports, we identified 266 patients with a diagnosis of benign papilloma on breast core biopsy. One hundred eighty-two patients underwent surgical resection. The final surgical pathology reports of all patients were reviewed and divided into one of two groups-benign or malignant. Twenty-one patients had a final diagnosis of in situ or invasive carcinoma, resulting in an upgrade rate of 12%. Radiologically detected lesions with calcifications were at higher risk for upgrade (OR = 4.45, 95% CI 1.08-18.27) than lesions without calcifications. Additionally, advanced patient age (OR = 1.07, 95% CI 1.03-1.13) and lesion size greater than 0.5 cm (OR = 2.59, 95% CI 0.38-17.48) was associated with upgrade to malignancy. Routine surgical excision of all papillomas is not recommended. Younger patients without high-risk features may benefit from clinical and radiologic follow-up alone. Accurate risk stratification will spare low-risk women unnecessary surgery.

A Review on Mammary Tumors in Rabbits: Translation of Pathology into Medical Care

Simple Summary

In recent years mammary cancer has been increasingly recognized in pet rabbits. In addition to uterine carcinomas—the most common tumor of female rabbits—mammary cancer can also markedly reduce the life expectancy of pet rabbits. The aim of this review is to raise awareness for these tumors and to report recent progress in related research. Their detailed characterization will likely improve medical care for affected rabbits. Moreover, study results will contribute to comparative pathology and may reveal if the rabbit is a suitable model for certain types of breast cancer in humans. Available information suggests that most invasive cancer cases develop through stepwise progression from non-invasive forms. Thus, early recognition will likely improve a complete cancer cure. So far, the only treatment option is surgical excision and prognostic factors are unknown. Recent investigations have identified tumor features with likely prognostic value. They have also revealed differences and similarities to mammary tumors in other species and breast cancer in women. Despite these initial data, continued research is necessary to gain more insights into the development of these tumors and their molecular features.

Abstract

The aim of this review is to raise awareness for mammary tumors in rabbits and to report progress in related research. Currently, a standardized tumor classification for rabbits is not available, prognostic factors are unknown and the only treatment option is surgical excision. Studies showed that affected rabbits have a wide age range and are nearly exclusively female or female spayed. Most mammary tumors are carcinomas. These may occur together with non-neoplastic or benign mammary lesions. Frequent microscopic findings are lipid droplets in tumor cells, secretory activity and microscopic heterogeneity. Since carcinomas are often negative for estrogen and progesterone receptors (ER-α/PR), modulation of receptor function will unlikely be beneficial for most rabbits. ER-α and PR status may have prognostic significance, since ER-α- or PR-negative tumors have significantly higher mitotic rates than ER-α- or PR-positive tumors. The frequent secretory activity of rabbit mammary tumors may suggest an influence of prolactin on tumorigenesis. Available data contribute to comparative pathology and are the basis for future molecular studies into the identification of additional prognostic factors and novel therapeutic options. They will also reveal the suitability of the rabbit as a model for certain types of breast cancer in women.

Expression of Myoepithelial Markers in Mammary Carcinomas of 119 Pet Rabbits

Simple Summary

Mammary cancer is a serious health issue in pet rabbits; prognostic factors are unknown. In a normal mammary gland, glandular secretory cells are surrounded by a single continuous layer of myoepithelial cells. In non-invasive mammary carcinomas, tumor cells are delineated by an intact myoepithelial layer, which is gradually lost to invasive carcinomas. The main aim of this study was to determine in rabbit mammary carcinomas (n = 119) the expression of myoepithelial markers that have prognostic significance in human cancer. Results show that all cases contained some retained myoepithelial cells. In 93% of the tumors, neoplastic cells expressed the myoepithelial marker calponin. There was a statistically significant association between higher percentages of calponin-containing cancer cells and histological features indicative of a better tumor differentiation, i.e., a lower proliferation of tumor cells, an increased percentage of tubular growth within the tumor, and a lower tumor grade, respectively. These results suggest that rabbit mammary carcinomas develop from progression of non-invasive cancer forms, and that calponin expression in cancer cells likely represents a favorable prognostic factor. The latter hypothesis has to be confirmed in long-term follow-up studies.

Abstract

Most mammary tumors in pet rabbits are carcinomas; prognostic factors are unknown. The aim of this study on rabbit mammary carcinomas was to determine the expression of myoepithelial markers that have a prognostic relevance in human cancers. Mammary carcinomas (n = 119) of female or female-spayed pet rabbits were immunostained for cytokeratin AE1/AE3, vimentin, smooth muscle actin (SMA), and calponin; and percentages of non-neoplastic myoepithelial cells (ME cells) and calponin-positive neoplastic cells were determined. Using statistical analysis, data were correlated with the age of the rabbits and histological tumor characteristics. All carcinomas contained retained spindle-shaped ME, while 115 also contained hypertrophic ME (HME). A statistically significant relationship existed between a higher age and an increase in HME. In 111 carcinomas (93%), tumor cells expressed calponin. There was a significant correlation between higher percentages of calponin-positive tumor cells and a lower mitotic count, an increased percentage of tubular growth, and a lower grading score, respectively. Data suggest that pet rabbit mammary carcinomas develop from progression of in situ cancer and that the extent of calponin expression in tumor cells influences their biological behavior. These results provide the basis for a long-term follow-up on the prognostic significance of calponin expression in mammary cancer cells.

Immunohistochemistry for diagnosis and prognosis of breast cancer: a review

Breast cancer is the most prevalent malignant tumor and main oncologic cause of mortality in women. Although most diagnosis of breast pathology is accomplished using hematoxylin and eosin stained sections, some cases require immunohistochemistry for proper evaluation. We investigated the latter cases including distinctions between ductal and lobular carcinoma, in situ and invasive carcinoma, typical ductal hyperplasia and atypical ductal hyperplasia/ductal carcinoma in situ, papillary and spindle cell lesion assessment, metastasis evaluation, and assessment of prognostic and therapy markers. E-cadherin is used to differentiate ductal and lobular carcinoma; 34βE12, CK8, p120 catenin and β-catenin also produce consistent results. Myoepithelial cell (MEC) stains are used to evaluate in situ and invasive carcinoma; calponin, smooth muscle myosin heavy chain and p63 are sensitive/specific markers. 34βE12 and CK5/6 are positive in ductal hyperplasia, which enables its differentiation from atypical ductal hyperplasia and ductal carcinoma in situ. CK 5/6, ER and MEC markers are consistent options for evaluating papillary lesions. Spindle cell lesions can be assessed using β-catenin, SMA, CD34, p63, CKs and hormone receptors. It is important to differentiate primary carcinomas from metastases; the most commonly used markers to identify breast origin include mammaglobin, GCDFP-15, GATA3 and ER, although none of these is completely sensitive or specific. Immunohistochemistry can be used to evaluate central prognostic and predictive factors including molecular subtypes, HER2, hormone receptors, proliferation markers (Ki-67) and lymph-vascular invasion markers including ERG, CD31, CD34, factor VIII and podoplanin. Owing to the complexity of mammary lesions, diagnosis also depends on each particular situation, evaluation of cytological characteristics revealed by immunochemistry and correlation with histological findings.

Differences in immunohistochemistry utilization by general and breast subspecialty pathologists at a large academic institution

OBJECTIVES

Immunohistochemistry (IHC) can be a useful adjunct in diagnostic breast pathology, but best practices have not been clearly established. We sought to compare the patterns of p63 utilization between general pathologists (GP) and subspecialized breast pathologists (BP), analyze diagnostic discrepancy rates, and identify types of lesions requiring immunohistochemistry.

METHODS

The pathology database was searched over 6-year period to identify breast needle core biopsy cases utilizing p63 and subsequent excision results.

RESULTS

P63 was ordered more frequently by BP (2.3% of cores) compared to GP (1.1% of cores, p = 0.0005). The most frequent utilization of p63 by GP for benign lesions (44.0%) followed by invasive carcinomas (36.0%) while BP most frequently ordered p63 on invasive carcinomas (49.5%) and DCIS (26.6%).

CONCLUSIONS

While IHC use may be thought to be most helpful to those with less experience or knowledge in breast pathology, these results suggest that utilization is increased with subspecialty training.

Thymidylate Synthase, a New Myoepithelial Biomarker for Breast Lesions

Background. The identification of myoepithelial cells (MECs) can facilitate the differential diagnosis of breast lesions. We previously found thymidylate synthase (TS) expression in the nuclei of MECs in breast tissues, which prompted us to investigate the usefulness of TS as a sensitive and specific biomarker in the differential diagnosis of breast lesions, similar to other MEC biomarkers (ie, tumor protein [P63] and cluster of differentiation 10 [CD10]). Methods. Immunohistochemistry for TS, P63, and CD10 was performed on paraffin sections from 189 breast specimens. Results. The results showed the intensity of the immunoreactive TS signal to be comparable with that of P63 in the nuclei of MECs. Furthermore, the nuclei of MECs stained strongly for TS and P63 in normal breast tissues (obtained adjacent to invasive breast lesions), benign breast lesions, and carcinoma in situ, whereas the cytoplasm of MECs stained strongly for CD10. The immunoreactive TS signal in the cytoplasm of MECs was variable in 22 out of 32 (65.6%) cases of invasive breast carcinoma and 4 out of 20 cases (20.0%) of ductal carcinoma in situ. We found no immunoreactive TS signal in the nuclei of luminal and stromal cells in breast lesions, although there was a weak positive signal in the cytoplasm of luminal and stromal cells. Conclusions. TS is a sensitive and specific MEC biomarker in the differential diagnosis of breast lesions.

MIND model for triple-negative breast cancer in syngeneic mice for quick and sequential progression analysis of lung metastasis

Mouse models of breast cancer with specific molecular subtypes (e.g., ER or HER2 positive) in an immunocompetent or an immunocompromised environment significantly contribute to our understanding of cancer biology, despite some limitations, and they give insight into targeted therapies. However, an ideal triple-negative breast cancer (TNBC) mouse model is lacking. What has been missing in the TNBC mouse model is a sequential progression of the disease in an essential native microenvironment. This notion inspired us to develop a TNBC-model in syngeneic mice using a mammary intraductal (MIND) method. To achieve this goal, Mvt-1and 4T1 TNBC mouse cell lines were injected into the mammary ducts via nipples of FVB/N mice and BALB/c wild-type immunocompetent mice, respectively. We established that the TNBC-MIND model in syngeneic mice could epitomize all breast cancer progression stages and metastasis into the lungs via lymphatic or hematogenous dissemination within four weeks. Collectively, the syngeneic mouse-TNBC-MIND model may serve as a unique platform for further investigation of the underlying mechanisms of TNBC growth and therapies.

Technical note: p40 antibody as a replacement for p63 antibody in bovine mammary immunohistochemistry

Tumor protein 63 (p63) is a nuclear antigen found in basal epithelial cells. To date, 10 isoforms of p63 have been identified, falling into 2 major groups identified by presence or absence of an N-terminal transactivation domain (TAp63 and ΔNp63, respectively). Literature suggests that ΔNp63 is the predominant form expressed in basal epithelial cells and myoepithelial cells (MYEC). The mouse anti-p63 antibody, clone 4B1E12, has been used as a specific nuclear marker for bovine MYEC. Unfortunately, this antibody is no longer commercially available. A new mouse monoclonal antibody, clone BC28, specific to ΔNp63 (designated p40) has been developed. We hypothesized that the p40 antibody would be an appropriate substitution as a MYEC and epithelial basal cell marker. An array of archived formalin-fixed, paraffin-embedded bovine tissues were subjected to immunohistochemical staining for either p40 or p63, with a subset being dual stained for direct comparison. Positive staining for p40 and p63 was observed in serial sections of mammary, skin, rumen, salivary gland, ureter, and bladder. As predicted, negative staining for p40 and p63 was observed in testis and intestine. Dual staining for p40 and p63 in calf mammary (n = 4), lactating mammary (n = 4), rumen (n = 4), and skin (n = 4) showed nearly 100% agreement. Thus, we established that the mouse monoclonal antibody, clone BC28, is a suitable replacement for anti-p63, clone 4B1E12, as a marker of MYEC and basal epithelial cells in bovine tissues.

Tubular variant of mammary adenomyoepithelioma: Diagnostic challenges and cytomorphological correlation in two cases

The authors describe the cytomorphologic features of two cases of tubular variant of adenomyoepithelioma of the breast that were first examined by fine-needle aspiration cytology (FNAC) and diagnosed as fibroadenoma. On retrospective review of the cytology, subtle features such as less cohesive epithelial clusters, intimate association of clusters of stromal cells with epithelial elements, a dominant population of plump-epithelioid naked (myoepithelial) cells, and occasional cells with intranuclear inclusions, were noted. Thus, these lesions can be diagnostically challenging and cannot be conclusively differentiated from either fibroadenoma or tubular adenoma cytologically and the pathologist may only be able to give a differential on FNAC. Recognition of the biphasic nature and the characteristic overall architecture of the tumors in combination with immunohistochemistry are essential to establish the correct diagnosis on biopsy. Although most tumors have a benign clinical course, rare instances of local recurrence, malignant transformation, and distant metastases have been reported. A complete excision with adequate margins would lower the chance of local recurrence.

Characterization of immortalized human mammary epithelial cell line HMEC 2.6

Primary human mammary epithelial cells have a limited life span which makes it difficult to study them in vitro for most purposes. To overcome this problem, we have developed a cell line that was immortalized using defined genetic elements, and we have characterized this immortalized non-tumorigenic human mammary epithelial cell line to establish it as a potential model system. human mammary epithelial cells were obtained from a healthy individual undergoing reduction mammoplasty at SIU School of Medicine. The cells were transduced with CDK4R24C followed by transduction with human telomerase reverse transcriptase. Post all manipulation, the cells displayed a normal cell cycle phase distribution and were near diploid in nature, which was confirmed by flow cytometry and karyotyping. In vitro studies showed that the cells were anchorage dependent and were non-invasive in nature. The cell line expressed basal epithelial markers such as cytokeratin 7, CD10, and p63 and was negative for the expression of estrogen receptor and progesterone receptor. Upon G-band karyotyping, the cell line displayed the presence of a few cytogenic abnormalities, including trisomy 20 and trisomy 7, which are also commonly present in other immortalized mammary cell lines. Furthermore, the benign nature of these cells was confirmed by multiple in vitro and in vivo experiments. Therefore, we think that this cell line could serve as a good model to understand the molecular mechanisms involved in the development and progression of breast cancer and to also assess the effect of novel therapeutics on human mammary epithelial cells.

Update on Immunohistochemical Analysis in Breast Lesions

CONTEXT

- The utility of immunohistochemistry (IHC) in breast lesions needs to be updated with exceptions among these lesions. Biomarker studies with IHC in triple-negative breast carcinoma may help develop targeted therapies for this aggressive breast cancer. The distinction of metastatic lung adenocarcinoma to the breast and invasive breast carcinoma has significant prognostic and therapeutic implications. The determination can be challenging because both primary tumors can express estrogen receptor and/or HER2 by IHC, creating a diagnostic dilemma.

OBJECTIVES

- To provide a practical update on the use of IHC markers in differential diagnoses in breast lesions, including benign, atypical, precancerous, and malignant tumors; to highlight recently published research findings on novel IHC markers in triple-negative breast carcinoma cases; and to reinforce the importance of IHC use as an ancillary tool in distinguishing metastatic lung adenocarcinoma to the breast from primary breast carcinoma using real case examples.

DATA SOURCES

- PubMed (US National Library of Medicine, Bethesda, Maryland) literature review and authors' research data and personal experiences were used in this review.

CONCLUSIONS

- Immunohistochemistry has an important role in making differential diagnoses in breast lesions in morphologically equivocal settings; recognizing IHC expression status in the exceptions among these lesions will aid in the correct diagnosis of challenging breast cases. Studies suggest that androgen receptor, p16, p53, GATA3, and PELP1 may have potential diagnostic, prognostic, and predictive value in triple-negative breast carcinoma cases; these findings may provide insight and a greater understanding of the tumor biology in triple-negative breast carcinomas. In distinguishing metastatic estrogen receptor-positive or HER2⁺ lung adenocarcinoma to the breast from primary breast carcinoma, napsin A, TTF-1, and GATA3 comprise a useful IHC panel.

A Comparative Study of Immunohistochemical Myoepithelial Cell Markers in Cutaneous Benign Cystic Apocrine Lesions

The use of immunohistochemical markers for myoepithelial cells (MEC) is a useful tool in the distinction of benign from malignant epithelial neoplasms. Although their use in breast tumors is well recognized, little is known concerning its application in comparable cutaneous lesions. Using benign cutaneous cystic apocrine lesions as a study model, the aim of this study was to compare 5 immunohistochemical markers [calponin, p63, smooth muscle actin (SMA), cytokeratin 14, and CD10] in their effectiveness to highlight MEC. Cases of apocrine hidrocystoma and cystadenoma (n = 44) were reviewed with a particular emphasis on proliferative features and apocrine change. The MEC staining pattern and the intensity and distribution scores in proliferative (n = 29) and nonproliferative (n = 15) lesions were assessed, and the differences between the 2 groups were statistically analyzed using Fisher exact test. Calponin and SMA stained MEC in the most consistent manner. Being a nuclear stain, p63 was easy to interpret but typically showed discontinuous staining. Cytokeratin 14 not only effectively highlighted MEC but also stained some luminal epithelial cells in an unpredictable manner. Because of prominent background dermal fibroblast staining, CD10 was often difficult to interpret. Only SMA and p63 showed a statistically significant difference in MEC staining intensity scores between the proliferative and nonproliferative groups. Our results show that immunohistological staining for MEC in benign cystic apocrine lesions of the skin is variable. The authors recommend that a panel of markers that includes calponin and p63 be used and highlight the need for awareness of specific caveats associated with individual markers.

Ras protein expression as a marker for breast cancer

Breast cancer, the most common neoplasm in women of all ages, is the leading cause of cancer-related mortality in women worldwide. Markers to help to predict the risk of progression and ultimately provide non-surgical treatment options would be of great benefit. At present, there are no available molecular markers to predict the risk of carcinoma in situ progression to invasive cancer; therefore, all women diagnosed with this type of malignancy must undergo surgery. Breast cancer is a heterogeneous complex disease, and different patients respond differently to different treatments. In breast cancer, analysis using immunohistochemical markers remains an essential component of routine pathological examinations, and plays an import role in the management of the disease by providing diagnostic and prognostic strategies. The aim of the present study was to identify a marker that can be used as a prognostic tool for breast cancer. For this purpose, we firstly used an established breast cancer model. MCF-10F, a spontaneously immortalized breast epithelial cell line was transformed by exposure to estrogen and radiation. MCF-10F cells were exposed to low doses of high linear energy transfer (LET) α particles (150 keV/μm) of radiation, and subsequently cultured in the presence of 17β-estradiol. Three cell lines were used: i) MCF-10F cells as a control; ii) Alpha5 cells, a malignant and tumorigenic cell line; and iii) Tumor2 cells derived from Alpha5 cells injected into nude mice. Secondly, we also used normal, benign and malignant breast specimens obtained from biopsies. The results revealed that the MCF-10F cells were negative for c-Ha-Ras protein expression; however, the Alpha5 and Tumor2 cell lines were positive for c-Ha-Ras protein expression. The malignant breast samples were also strongly positive for c-Ha-Ras expression. The findings of our study indicate that c-Ha-Ras protein expression may be used as a marker to predict the progression of breast cancer; this marker may also ultimately provide non-surgical treatment options for patients who are at a lower risk.

Novel Use for DOG1 in Discriminating Breast Invasive Carcinoma from Noninvasive Breast Lesions

Aims. DOG1 has proven to be a useful marker of gastrointestinal stromal tumors (GISTs). Recently, DOG1 expression has also been reported in some non-GIST malignant tumors, but the details related to DOG1 expression in breast tissue remain unclear. The aim of this study was to detect the expression of DOG1 in the human breast and to evaluate the feasibility of using DOG1 to discriminate between invasive breast carcinoma and noninvasive breast lesions. Methods and Results. A total of 210 cases, including both invasive and noninvasive breast lesions, were collected to assess DOG1 expression immunohistochemically. DOG1 expression was consistently positive in breast myoepithelial cells (MECs), which was similar to the results obtained for three other MEC markers: calponin, smooth muscle myosin heavy chain (SMMHC), and P63 (P > 0.05 in all). Importantly, DOG1 was useful in discriminating invasive breast carcinoma from noninvasive breast lesions (P < 0.05). Conclusions. DOG1 is a useful marker of breast MECs, and adding DOG1 to the MEC identification panel will provide more sophisticated information when diagnosing uncertain cases in the breast.

Malignant Adenomyoepithelioma of the Breast and Responsiveness to Eribulin

Adenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by its dual differentiation into luminal cells and myoepithelial cells. In most cases these tumors have a benign clinical course, but distant metastases have been reported. We present the case of a 51-year-old woman diagnosed with malignant AME. The patient underwent a right modified radical mastectomy, and pathological examination confirmed the diagnosis of malignant AME. Ten months after the operation, multiple hepatic, pleural, and abdominal wall metastases were detected. A number of palliative chemotherapeutic agents were tried, including anthracycline and taxanes. However, the disease continued to progress, and superior vena cava syndrome developed as a result of direct tumor invasion. The patient received salvage eribulin monotherapy. After two cycles of this treatment, her clinical symptoms were ameliorated, and a computed tomography scan showed a partial response. Eribulin chemotherapy was thus effective in treating malignant AME in this case.

Myoepithelial cell differentiation markers in ductal carcinoma in situ progression

We describe a preclinical model that investigates progression of early-stage ductal carcinoma in situ (DCIS) and report that compromised myoepithelial cell differentiation occurs before transition to invasive disease. Human breast cancer MCF10DCIS.com cells were delivered into the mouse mammary teat by intraductal injection in the absence of surgical manipulations and accompanying wound-healing confounders. DCIS-like lesions developed throughout the mammary ducts with full representation of human DCIS histologic patterns. Tumor cells were incorporated into the normal mammary epithelium, developed ductal intraepithelial neoplasia and DCIS, and progressed to invasive carcinoma, suggesting the model provides a rigorous approach to study early stages of breast cancer progression. Mammary glands were evaluated for myoepithelium integrity with immunohistochemical assays. Progressive loss of the myoepithelial cell differentiation markers p63, calponin, and α-smooth muscle actin was observed in the mouse myoepithelium surrounding DCIS-involved ducts. p63 loss was an early indicator, calponin loss intermediate, and α-smooth muscle actin a later indicator of compromised myoepithelium. Loss of myoepithelial calponin was specifically associated with gain of the basal marker p63 in adjacent tumor cells. In single time point biopsies obtained from 16 women diagnosed with pure DCIS, a similar loss in myoepithelial cell markers was observed. These results suggest that further research is warranted into the role of myoepithelial cell p63 and calponin expression on DCIS progression to invasive disease.

Endocrine mucin-producing sweat gland carcinoma: a study of three cases and CK8, CK18 and CD5/6 immunoexpression

Endocrine mucin-producing sweat gland carcinoma is a cutaneous adnexal tumor that is rarely reported in the literature. We identified only 29 previously reported cases. All these cases share some clinical morphologic and immunohistochemical features. Among the immunohistochemical markers, cytokeratins 5/6, 8 and 18 (CK5/6, CK8 and CK18) had not been previously studied in this tumor. Although studies with cytokeratin Cam5.2 exist, we know at present that this marker does not correspond to antibodies CK8/18, but rather to CK7 and CK8. We studied three examples of endocrine mucin-producing sweat gland carcinoma with 18 immunostains. Our cases showed an immunoprofile CK8+, CK18+, CK5/6- (or only focally positive), CK7+, GCDFP-15+ (2 cases), estrogen receptor+, progesterone receptor+, HER2-, neuron-specific enolase + (2 cases), anti-synaptophysin+, chromogranin A +, CD56 variable (1 case +, 1 case-), CD57-, anti-human D2-40- (two cases), p63- or focally positive, smooth muscle actin + with variable pattern of expression and smooth muscle myosin heavy chain expressed in a peripheral discontinuous layer in some nodules, but absent in most.

Immunostaining of ∆Np63 (using the p40 antibody) is equal to that of p63 and CK5/6 in high-grade ductal carcinoma in situ of the breast

As a result of breast cancer screening programs, high-grade ductal carcinoma in situ (DCIS) of the breast is diagnosed more often. Frequently, a DCIS diagnosis can only be made using immunohistochemical stains to visualize the myoepithelial layer in order to assess microinvasion. Standard markers for myoepithelial cells are CK5/6 and p63. An isoform of the latter, ∆Np63, is recognized by a recently developed antibody, p40. Here, we compare the standard myoepithelial markers CK5/6 and p63 with p40. We immunostained full sections of tissue samples of 35 high-grade DCIS and compared the staining pattern of CK5/6, p63 and p40 in tumour tissue and in normal glands. Staining patterns of myoepithelial cells for p63 and p40 were similar in terms of the percentage of stained nuclei. In all cases, p63 was strongly expressed, while this was the case for p40 in 31 (89%) and moderately in 4 (11%) cases. All but one case (97%) showed a similar percentage of stained myoepithelial cells in comparing CK5/6 and p40 staining. CK5/6 expression was heterogeneous and strong/moderate/weak in 60, 34 and 6 % respectively. Compared to surrounding normal glands, staining of myoepithelial cells for all three markers in the neoplastic lesion was attenuated. In high-grade DCIS, p40 staining is highly specific for myoepithelial cells. Its staining pattern and intensity are equal to p63, which opens up its use for daily practice. Staining with p40 is less heterogeneous than that for CK5/6.

Application of immunohistochemistry in breast pathology: a review and update

CONTEXT

Immunohistochemistry is a valuable tool in routine breast pathology, used for both diagnostic and prognostic parameters. The diagnostic immunomarkers are the scope of this review. Most breast lesions can be diagnosed on routine hematoxylin-eosin sections; however, in several scenarios, such as morphologically equivocal cases or metastatic tumors of unknown primary, the appropriate application of immunohistochemistry adds true value in reaching an accurate diagnosis.

OBJECTIVE

To evaluate the diagnostic utility of the most commonly studied immunomarkers in the field of breast pathology by review of the literature, using the database of indexed articles in PubMed (US National Library of Medicine, Bethesda, Maryland) from 1976 to 2013.

DATA SOURCES

Literature review, and author's research data and personal practice experience.

CONCLUSIONS

The appropriate use of immunohistochemistry by applying a panel of immunomarkers and using a standardized technical and interpretational method will complement the morphologic assessment and aid in the accurate classification of difficult breast lesions and the identification of metastasis from a breast primary.

Immunohistochemical expression of myoepithelial markers in adenomyoepithelioma of the breast: a unique paradoxical staining pattern of high-molecular weight cytokeratins

To determine which immunohistochemical markers are useful for the identification of neoplastic myoepithelial cells in adenomyoepithelioma of the breast, the expression of seven myoepithelial markers (α-smooth muscle actin (α-SMA), calponin, p63, CD10, cytokeratin 5/6, cytokeratin 14, and S-100) was examined in 19 lesions from 16 patients. The lesion consisted of seven spindle and 12 clear cell lesions. For normal myoepithelial cells, α-SMA, calponin, and p63 were significantly more sensitive than cytokeratin 5/6, cytokeratin 14, and S-100. There was no significant difference in the expression of α-SMA, calponin, p63, and CD10 in neoplastic myoepithelial cells of adenomyoepithelioma regardless of spindle or clear cell types. In spindle cell lesions, high-molecular weight cytokeratins (HMWCK; cytokeratin 5/6 and cytokeratin 14) tended to show higher staining scores and S-100 showed lower staining scores than other markers. In clear cell lesions, HMWCK showed significantly lower staining scores than the other five markers. There was no significant difference in staining scores among the other five markers. HMWCK showed a unique paradoxical staining pattern in clear cell lesions, with diffusely positive inner epithelial cells and completely negative outer myoepithelial cells. Although the sensitivity of HMWCK in clear cell lesions is low, with this unique paradoxical staining pattern and relatively high sensitivity in spindle cell lesions, HMWCK could be useful in diagnosing adenomyoepithelioma. In choosing immunohistochemical markers, any of the seven markers are useful, but combining HMWCK and any one of α-SMA, calponin, and p63 would be a good panel for the diagnosis of adenomyoepithelioma.

Randomized trial of preoperative docetaxel with or without capecitabine after 4 cycles of 5-fluorouracil– epirubicin–cyclophosphamide (FEC) in early-stage breast cancer: exploratory analyses identify Ki67 as a predictive biomarker for response to neoadjuvant chemotherapy

This randomized, multicenter study compared the efficacy of docetaxel with or without capecitabine following fluorouracil/epirubicin/cyclophosphamide (FEC) therapy in operable breast cancer and investigated the role of Ki67 as a predictive biomarker. Patients were randomized to 4 cycles of docetaxel/capecitabine (docetaxel: 75 mg/m² on day 1; capecitabine: 1,650 mg/m² on days 1–14 every 3 weeks) or docetaxel alone (75 mg/m² on day 1 every 3 weeks) after completion of 4 cycles of FEC (5-fluorouracil 500 mg/m², epirubicin 100 mg/m² and cyclophosphamide 500 mg/m² on day 1 every 3 weeks). The primary endpoint was the pathological complete response (pCR) rate. Predictive factor analysis was conducted using clinicopathological markers, including hormone receptors and Ki67 labeling index (Ki67LI). A total of 477 patients were randomized; the overall response in the docetaxel/capecitabine and docetaxel groups was 88.3 and 87.4 %, respectively. There were no significant differences in the pCR rate (docetaxel/capecitabine: 23 %; docetaxel: 24 %; p = 0.748), disease-free survival, or overall survival. However, patients with mid-range Ki67LI (10–20 %) showed a trend towards improved pCR rate with docetaxel/capecitabine compared to docetaxel alone. Furthermore, multivariate logistic regression analysis showed pre-treatment Ki67LI (odds ratio 1.031; 95 % CI 1.014–1.048; p = 0.0004) to be a significant predictor of pCR in this neoadjuvant treatment setting. Docetaxel/capecitabine (after 4 cycles of FEC) did not generate significant improvement in pCR compared to docetaxel alone. However, exploratory analyses suggested that assessment of pre-treatment Ki67LI may be a useful tool in the identification of responders to preoperative docetaxel/capecitabine in early-stage breast cancer.

Changes in breast cancer reports after pathology second opinion

Breast cancer pathology reports contain valuable information about the histologic diagnosis, prognostic factors and predictive indicators of therapeutic response. A second opinion may be requested by medical oncologists and surgeons, when a patient is referred from another institution for treatment. We report the experience with pathology second opinion in selected patients referred to the Breast Oncology Unit. 205 cases referred to the Breast Oncology Unit were selected for second opinion after clinical evaluation, between 2002 and 2012. The cases reviewed included 102 core needle biopsies, 88 surgical specimens from the breast and 18 lymphadenopathies, 14 from the axillary region. Pathology second opinion was based on a review of hematoxylin-eosin preparations, recuts of submitted paraffin blocks and written external pathology reports. Immunohistochemical studies for hormone receptors, HER2, myoepithelial cells, and other markers were performed in selected cases. A case was reclassified as showing major change when second opinion showed a potential for significant change in prognosis or treatment. Otherwise, it was considered to represent minor change or to be concordant. In 52 cases (25.4%), the pathology review showed changes. Thirty-three (16%) patients were reclassified for major changes and 19 (9.2%) as minor changes. In six patients, more than one major change was identified. The major discrepancies identified were related to the histologic classification (12 cases), the presence or absence of invasion in ductal carcinoma (15 cases), the results of hormone receptors (5 cases), and HER2 (7 cases). Major changes in histologic classification included two cases diagnosed as invasive ductal carcinoma and reclassified as benign, four cases with diagnosis of breast cancer reclassified as metastatic lung cancer, one case diagnosed as small cell carcinoma of lung metastatic in the breast, reclassified as primary carcinoma of the breast, and three cases with diagnosis of breast cancer in the axilla reclassified as primary cutaneous adnexal carcinomas (2) and metastatic melanoma (1), respectively. In two cases, the histologic type of the primary breast tumor was changed. Second opinion in breast pathology may uncover significant discrepancies that impact on patient management and prognosis. Major discrepancies are most frequently related to the assessment of the presence or absence of invasion in ductal carcinoma, the results of predictive makers of therapeutic response, and the differential diagnosis of breast cancer and nonmammary tumors in the breast, the axilla, and at distant sites.

Adenoma of the nipple: A clinicopathological report of 13 cases

Adenoma of the nipple (AN) represents a rare benign mammary proliferation of lactiferous ducts. It appears as an erosive or ulcerative lesion, which in a number of cases is associated with a serous/hematic secretion. AN may be clinically confused with Paget's disease and histologically with invasive breast carcinoma or breast cancer precursor lesions. Therefore, the histological and immunophenotypic analysis is essential for the differential diagnosis. The present study describes the histopathological characteristics of a first case series of AN.

Clinicopathological significance of 'atypical ductal proliferation' in core needle biopsy of the breast

Atypical ductal proliferation or ADP has been used in histopathological diagnosis of core needle biopsy (CNB) but its details have not been well studied. Therefore, we examined the clinicopathological characteristics of the initial CNB cases diagnosed as 'ADP ' who subsequently turned out to be malignant, and compared the findings to those that did not. Among 101 cases initially diagnosed as ADP in CNB, the second biopsy revealed no carcinoma (38), ductal carcinoma in situ (DCIS) (45) and invasive carcinoma (18). Significant differences were detected between those which turned out to be carcinoma and those that did not, in the status of myoepithelial cells identified by p63 immunohistochemistry (P = 0.026) and ultrasound (US) categories (P < 0.001). We further compared the histopathological characteristics of those initially diagnosed as ADP and subsequently as DCIS or invasive ductal carcinoma (IDC) with those initially diagnosed as such. DCIS or IDC cases initially diagnosed as ADP had significantly lower Ki67 labeling index (P < 0.01, P < 0.01) and histological grade using Van nuys prognostic index (P < 0.01) or Nottingham histological grades (P < 0.01) respectively than those initially as DCIS or IDC. An assessment of myoepithelial components with US findings might contribute to determine the subsequent clinical algorithm of the patients diagnosed as ADP at initial CNB.

Diagnostic role of immunohistochemistry in the evaluation of breast pathology specimens

CONTEXT

Immunohistochemistry plays a vital role in the evaluation of breast pathology specimens.

OBJECTIVE

To discuss the role of myoepithelial cell markers in the evaluation of various breast lesions. Other markers, such as E-cadherin and those used to differentiate mammary carcinoma from metastatic tumors to the breast, and markers used in the differential diagnosis of Paget disease, are also discussed.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature.

CONCLUSIONS

Myoepithelial cell markers vary in their sensitivity and specificity, and one should be aware of the potential pitfalls in interpretation. Using panels of 2 or more myoepithelial cell markers is always recommended, either singly or in cocktail forms. Although negative E-cadherin staining supports the diagnosis of lobular origin, positive staining does not rule it out. Immunohistochemistry can be helpful in differentiating Paget disease from its mimics. Although metastatic tumors to the breast are rare, a triple-negative immunophenotype and absence of an in situ component should be a "red flag" for such possibility, especially in patients with clinical history of an extramammary malignancy.

[Papillary lesions of the breast]

Papillary lesions of the breast encompass a spectrum of both benign and malignant lesions despite sharing a similar basic architecture. A reliable distinction between the different entities is possible even in biopsies with precise knowledge of the diagnostic criteria and using immunohistochemistry as a diagnostic adjunct. These include papilloma, papillary ductal carcinoma in situ, encapsulated papillary carcinoma and solid papillary carcinoma. Architectural features, cellular composition and distribution of myoepithelial cells as highlighted by immunohistochemistry are the major diagnostic criteria. In this review the most useful morphological and immunohistochemical criteria for routine diagnostic practice are presented.

Canine mammary tumors: a review and consensus of standard guidelines on epithelial and myoepithelial phenotype markers, HER2, and hormone receptor assessment using immunohistochemistry

Although there have been several studies on the use of immunohistochemical biomarkers of canine mammary tumors (CMTs), the results are difficult to compare. This article provides guidelines on the most useful immunohistochemical markers to standardize their use and understand how outcomes are measured, thus ensuring reproducibility of results. We have reviewed the biomarkers of canine mammary epithelial and myoepithelial cells and identified those biomarkers that are most useful and those biomarkers for invasion and lymph node micrometastatic disease. A 10% threshold for positive reaction for most of these markers is recommended. Guidelines on immunolabeling for HER2, estrogen receptors (ERs), and progesterone receptors (PRs) are provided along with the specific recommendations for interpretation of the results for each of these biomarkers in CMTs. Only 3+ HER2-positive tumors should be considered positive, as found in human breast cancer. The lack of any known response to adjuvant endocrine therapy of ER- and PR-positive CMTs prevents the use of the biological positive/negative threshold used in human breast cancer. Immunohistochemistry results of ER and PR in CMTs should be reported as the sum of the percentage of positive cells and the intensity of immunolabeling (Allred score). Incorporation of these recommendations in future studies, either prospective or retrospective, will provide a mechanism for the direct comparison of studies and will help to determine whether these biomarkers have prognostic significance. Finally, these biomarkers may ascertain the most appropriate treatment(s) for canine malignant mammary neoplasms.

Adenomyoepithelioma of the Breast: A Brief Diagnostic Review

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.

Prognostic impact of CD10 expression in clinical outcome of invasive breast carcinoma

BACKGROUND

Early diagnosis and treatment for breast cancers has greatly improved in recent years, however, subset of this disease with early recurrence have remained to be unpredictable. Several studies has addressed that strong CD10 expression in tumor stroma is associated with poor survival rate of breast cancers, but no correlation between CD10 expression and disease-free survival has been elucidated yet. For these reasons, this study with modified immunohistochemical (IHC) staining evaluated the expression of CD10 in invasive breast carcinomas (IBCs) and analyzed correlations between CD10 expression on tumor cells, stromal cells and myeloid-like cells with clinicopathological parameters and recurrence status.

METHOD

IHC staining method was performed on formalin-fixed paraffin-embedded sections of 73 cases of primary IBCs, with record of pathological characteristics of subjects followed up from 1998 to 2007.

RESULTS

Stromal CD10 expression was observed in 39/73 cases (53.4 %) with strong expression in 41.0 %. Three cases stained positive for myeloid-like cells and five for carcinomatous cells, of which 6 cases had recurrence and/or regional LN status. Stromal CD10 expression was significantly higher in the unfavorable group (69.6 %; 16/23 cases) compared with the favorable group (32.1 %; 9/28 cases) (p = 0.048). The levels of CD10 expression showed significant difference among clinical outcomes (recurrence or non-recurrence), independent of regional LN status (p = 0.034), histology type (p = 0.044), ER status (p = 0.042), PgR status (p = 0.039), Her2 status (p = 0.038) and Ki67 index (p = 0.036) (partial Pearson correlations). Cox proportional-hazards regression showed that risk factors for disease-free survival were stromal CD10 expression [CD10±, CD10+ versus CD10++; p = 0.003; HR 2.824 (1.427-5.591)]; regional LN status [N0, N1, N2, versus N3; p = 0.004; HR 2.107 (1.262-3.517)] and PgR status [negative versus positive, p = 0.006, HR 0.172 (0.049-0.596)].

CONCLUSION

CD10 expression on stroma with or without other positive tumor cells and/or myeloid-like cells may function as a powerful prognostic factor for IBC disease-free survival rates, predicting of potential recurrence. It can be determined by a simple modified IHC staining method, which is independent of other prognostic morphologic markers and biomarkers in IBC.

Myoepithelial and epithelial-myoepithelial, mesenchymal and fibroepithelial breast lesions: updates from the WHO Classification of Tumours of the Breast 2012

In the 4th edition of the WHO Classification of Tumours of the Breast, myoepithelial lesions are retitled myoepithelial and epithelial-myoepithelial lesions in order to better reflect the dual participation of luminal and myoepithelial compartments in some key entities. Malignant myoepithelioma, described as a section within the chapter on myoepithelial lesions in the 3rd edition, is recognised in the 4th edition as part of metaplastic carcinoma. Adenomyoepithelioma with malignancy is categorised in terms of the cellular component undergoing malignant transformation. The list of antibodies that can be used for identifying myoepithelial cells is updated. Among mesenchymal lesions, new additions are nodular fasciitis and atypical vascular lesions, while the haemangiopericytoma is removed. The 3rd edition stated that pathological prediction of behaviour of phyllodes tumours is difficult in the individual case. In the 4th edition, some progress has been made in prioritisation and weighting of histological parameters that can potentially estimate probability of recurrence. The WHO Working Group advocates leaning towards a diagnosis of fibroadenoma in cases where there is histological uncertainty in distinction from a benign phyllodes tumour, or adopting the neutral term 'benign fibroepithelial neoplasm', as the clinical behaviour of fibroadenoma overlaps with that of benign phyllodes tumour. The 3rd edition terminology of 'periductal stromal sarcoma' is revised to 'periductal stromal tumour', akin to the widespread consensus to avoid the use of the term 'cystosarcoma' in the context of phyllodes tumours.

Myoepithelial cell differentiation markers in prepubertal bovine mammary gland: effect of ovariectomy

We reported previously that ovariectomy alters prepubertal development of mammary myoepithelial cells (MC) by mechanisms that are not well understood. Therefore, in the present study, we analyzed expression of 2 myoepithelial differentiation markers, α-smooth muscle actin (SMA) and the common acute lymphoblastic leukemia antigen (CD10), in mammary parenchymal tissue from intact (INT) and ovariectomized (OVX) heifers. On d 40, Holstein heifers underwent either an ovariectomy (OVX; n=16) or a sham (INT; n=21) operation. At 55, 70, 85, 100, 130, and 160 d of age, tissues were collected, and multispectral imaging was used to quantify immunofluorescent staining for myoepithelial cell (MC) markers. Fluorescent intensity (FI) of the markers was normalized against a control sample. In the basal epithelial layer, CD10 FI was less and SMA FI was greater in OVX than INT. The ratio of SMA to CD10 FI, as a proxy indicator for MC differentiation, was greater in tissue from OVX compared with INT heifers after 55 d of age. The staining for SMA was frequently more intense along the basal aspect of cells, whereas CD10 expression was localized on the apical surface of the MC. In mammary tissue from both INT and OVX heifers, we observed basal cells that were negative for both CD10 and SMA, some of which appeared to span the distance from basement membrane to the ductal lumen. Interestingly, we also observed CD10+ cells adjacent to the ductal lumen, a situation that was more prevalent in OVX than in INT heifers. Also, ovariectomy affects MC expression of both SMA and CD10, as well as the pattern of MC development. Myoepithelial cells are known to limit parenchymal growth in other species. Involvement of MC as regulators of prepubertal bovine mammary development is worthy of further investigation.

Morphology of the myoepithelial cell: immunohistochemical characterization from resting to motile phase

Myoepithelium is present in canine mammary tumors as resting and proliferative suprabasal and spindle and stellate interstitial cells. The aim of this paper was to evaluate a panel of markers for the identification of four different myoepithelial cell morphological types in the normal and neoplastic mammary gland and to investigate immunohistochemical changes from an epithelial to a mesenchymal phenotype. Cytokeratin 19 (CK19), cytokeratin 5/6 (CK5/6), cytokeratin 14 (CK14), estrogen receptor (ER), p63 protein, vimentin (VIM), and α-smooth muscle actin (Alpha-SMA) antibodies were used on 29 neoplasms (3 benign and 3 malignant myoepithelial tumors, 7 carcinomas in benign-mixed tumors and 16 complex carcinomas) and on normal tissue of mammary glands. All these antibodies were also tested on 3 mammary tissues from animals with no mammary pathology. The myoepithelial markers were well expressed in the suprabasal cells and gradually lost in the motile types, with the stellate cells maintaining only VIM expression typical of mesenchyma. ER labeled some resting and motile myoepithelial cells. On the basis of our results, we propose a transition from myoepithelial immotile cells into migratory fibroblast-like cells. This transition and the characterization of an immunohistochemical panel for resting and motile myoepithelial cells shed more light on the biological behavior of myoepithelial cells.

Parathyroid hormone-related protein is not required for normal ductal or alveolar development in the post-natal mammary gland

PTHrP is necessary for the formation of the embryonic mammary gland and, in its absence, the embryonic mammary bud fails to form the neonatal duct system. In addition, PTHrP is produced by the breast during lactation and contributes to the regulation of maternal calcium homeostasis during milk production. In this study, we examined the role of PTHrP during post-natal mammary development. Using a PTHrP-lacZ transgenic mouse, we surveyed the expression of PTHrP in the developing post-natal mouse mammary gland. We found that PTHrP expression is restricted to the basal cells of the gland during pubertal development and becomes expressed in milk secreting alveolar cells during pregnancy and lactation. Based on the previous findings that overexpression of PTHrP in cap and myoepithelial cells inhibited ductal elongation during puberty, we predicted that ablation of native PTHrP expression in the post-natal gland would result in accelerated ductal development. To address this hypothesis, we generated two conditional models of PTHrP-deficiency specifically targeted to the postnatal mammary gland. We used the MMTV-Cre transgene to ablate the floxed PTHrP gene in both luminal and myoepithelial cells and a tetracycline-regulated K14-tTA;tetO-Cre transgene to target PTHrP expression in just myoepithelial and cap cells. In both models of PTHrP ablation, we found that mammary development proceeds normally despite the absence of PTHrP. We conclude that PTHrP signaling is not required for normal ductal or alveolar development.

Expression and role of fibroblast activation protein-alpha in microinvasive breast carcinoma

BACKGROUND

Diagnosis of ductal carcinoma in situ (DCIS) in breast cancer cases is challenging for pathologist due to a variety of in situ patterns and artefacts, which could be misinterpreted as stromal invasion. Microinvasion is detected by the presence of cytologically malignant cells outside the confines of the basement membrane and myoepithelium. When malignant cells invade the stroma, there is tissue remodeling induced by perturbed stromal-epithelial interactions. Carcinoma-associated fibroblasts (CAFs) are main cells in the microenvironment of the remodeled tumor-host interface. They are characterized by the expression of the specific fibroblast activation protein-alpha (FAP-α), and differ from that of normal fibroblasts exhibiting an immunophenotype of CD34. We hypothesized that staining for FAP-α may be helpful in determining whether DCIS has microinvasion.

METHODS

349 excised breast specimens were immunostained for smooth muscle actin SMA, CD34, FAP-α, and Calponin. Study material was divided into 5 groups: group 1: normal mammary tissues of healthy women after plastic surgery; group 2: usual ductal hyperplasia (UDH); group 3: DCIS without microinvasion on H & E stain; group 4: DCIS with microinvasion on H & E stain (DCIS-MI), and group 5: invasive ductal carcinoma (IDC). A comparative evaluation of the four immunostains was conducted.

RESULTS

Our results demonstrated that using FAP-α and Calponin adjunctively improved the sensitivity of pathological diagnosis of DCIS-MI by 11.29%, whereas the adjunctive use of FAP-α and Calponin improved the sensitivity of pathological diagnosis of DCIS by 13.6%.

CONCLUSIONS

This study provides the first evidence that immunostaining with FAP-α and Calponin can serve as a novel marker for pathologically diagnosing whether DCIS has microinvasion.