'Revertant' DCIS in human axillary breast carcinoma metastases

Ductal Carcinoma Arising in a Squamous Epithelial Inclusion Cyst within an Axillary Lymph Node: A Challenging Nodal Metastasis

Introduction. Assessment of axillary lymph nodes in breast carcinoma is an important part of staging to guide appropriate clinical management. Lymph node inclusions of different types, including nevoid, squamous, and glandular, are rare but have been reported in multiple different anatomic locations including the axilla. These can result in diagnostic challenges and pose risks of misdiagnoses. Rarely, malignancies may arise intrinsic to otherwise incidental benign nodal inclusions. Case Presentation. We report a case of ductal carcinoma diagnosed within a squamous epithelial inclusion cyst within an axillary lymph node in a patient with pure ductal carcinoma in situ (DCIS) of the ipsilateral right breast. To our knowledge, this is the fifth report in the literature of breast carcinoma confirmed within an axillary inclusion in a patient with pure DCIS. Evaluation of the primary DCIS and lymph node inclusions, by routine and immunohistochemical stains, was performed for assessment. Discussion. The presence of lymph node inclusions can pose a challenge in assessment of benignity and malignancy, on frozen and permanent histologic sections. Pathologists should carefully evaluate lymph node inclusions to ensure that intrinsic malignancies are not missed within rare otherwise benign appearing incidental epithelial rests.

Misleading images of ductal carcinoma in situ: 4 lymph nodes with metastasis

Since sentinel lymph node examination became routine, findings of benign ectopic breast tissue in lymph nodes have increased. We report images of ductal carcinoma in situ (DCIS) in four lymph nodes in a 76-year-old woman with bilateral breast carcinoma. The right lumpectomy showed intermixed invasive lobular and ductal carcinoma, plus DCIS. 19 nodes were isolated in the axillary lymphadenectomy, 4 of which displayed solid and cribriform DCIS. Myosin and p63 immunohistochemical techniques were positive, suggesting an erroneous diagnosis of "metastatic DCIS". A further three cases of DCIS in lymph nodes have been previously reported, all with a distinct layer of myoepithelial cells with actin, myosin or p63. Biologically, these images of DCIS in lymph nodes are not credible and three major hypotheses have been proposed to explain these findings: Iatrogenic Mechanical Transport, Revertant DCIS, and primary DCIS of lymph nodes. We consider the first one the most plausible explanation. Our case is unique as several, rare findings are simultaneously observed. More new cases, together with additional immunohistochemical techniques and molecular testing on previous cases, are needed to find a definitive explanation of this histologic finding.

Defining invasion in breast cancer: the role of basement membrane

Basement membrane (BM) is an amorphous, sheet-like structure separating the epithelium from the stroma. BM is characterised by a complex structure comprising collagenous and non-collagenous proteoglycans and glycoproteins. In the breast, the thickness, density and composition of the BM around the ductal lobular system vary during differing development stages. In pathological conditions, the BM provides a physical barrier that separates proliferating intraductal epithelial cells from the surrounding stroma, and its absence or breach in malignant lesions is a hallmark of invasion and metastases. Currently, diagnostic services often use special stains and immunohistochemistry (IHC) to identify the BM in order to distinguish in situ from invasive lesions. However, distinguishing BM on stained sections, and differentiating the native BM from the reactive capsule or BM-like material surrounding some invasive malignant breast tumours is challenging. Although diagnostic use of the BM is being replaced by myoepithelial cell IHC markers, BM is considered by many to be a useful marker to distinguish in situ from invasive lesions in ambiguous cases. In this review, the structure, function and biological and clinical significance of the BM are discussed in relation to the various breast lesions with emphasis on how to distinguish the native BM from alternative pathological tissue mimicking its histology.

Histopathological growth patterns of liver metastasis: updated consensus guidelines for pattern scoring, perspectives and recent mechanistic insights

The first consensus guidelines for scoring the histopathological growth patterns (HGPs) of liver metastases were established in 2017. Since then, numerous studies have applied these guidelines, have further substantiated the potential clinical value of the HGPs in patients with liver metastases from various tumour types and are starting to shed light on the biology of the distinct HGPs. In the present guidelines, we give an overview of these studies, discuss novel strategies for predicting the HGPs of liver metastases, such as deep-learning algorithms for whole-slide histopathology images and medical imaging, and highlight liver metastasis animal models that exhibit features of the different HGPs. Based on a pooled analysis of large cohorts of patients with liver-metastatic colorectal cancer, we propose a new cut-off to categorise patients according to the HGPs. An up-to-date standard method for HGP assessment within liver metastases is also presented with the aim of incorporating HGPs into the decision-making processes surrounding the treatment of patients with liver-metastatic cancer. Finally, we propose hypotheses on the cellular and molecular mechanisms that drive the biology of the different HGPs, opening some exciting preclinical and clinical research perspectives.

The vulnerable primed cancer stem cells in disguise: demystifying the role of Maspin

Epithelial-specific Maspin is widely known as a tumor suppressor. However, while the level of maspin expression is inversely correlated with tumor grade and stage, emerging clinical evidence shows a correlation between seemingly better differentiated tumor cells that express Maspin in both the nucleus and the cytoplasm, (n + c)Maspin, with a poor prognosis of many types of cancer. Biological studies demonstrate that Maspin plays an essential role in stem cell differentiation. In light of the recently established characterization of primed stem cells (P-SCs) in development, we propose, for the first time, that cancer stem cells (CSCs) also need to undergo priming (P-CSCs) before their transition to various progeny phenotypes. We envisage major differences in the steady state kinetics between P-SCs and P-CSCs. We further propose that P-CSCs of carcinoma are both marked and regulated by (n + c)Maspin. The concept of P-CSCs helps explain the apparent dichotomous relationships of (n + c)Maspin expression with cancer diagnosis and prognosis, and is supported by the evidence from mechanistic studies. We believe that the potential utility of (n + c)Maspin as a molecular marker of P-CSCs may significantly accelerate the advancement in our understanding of the genesis of tumor phenotypic plasticity in response to changes of tumor microenvironments (TME) or drug treatments. The vulnerabilities of the cellular state of (n + c)Maspin-expressing P-CSCs are also discussed as the rationale for future development of P-CSC-targeted chemotherapeutic and immunotherapeutic strategies.

Specific cell differentiation in breast cancer: a basis for histological classification

Breast parenchyma progenitor cells show a high degree of phenotypic plasticity reflected in the wide range of morphology observed in benign and malignant breast tumours. Although there is evidence suggesting that all breast cancer (BC) arises from a common epithelial progenitor or stem cell located at the terminal duct lobular units (TDLUs), BC shows a broad spectrum of morphology with extensive variation in histological type and grade. This is related to the complexity of BC carcinogenesis including initial genetic changes in the cell of origin, subsequent genetic and epigenetic alterations and reprogramming that occur at various stages of BC development and the interplay with the surrounding microenvironment, factors which influence the process of differentiation. Differentiation in BC determines the morphology, which can be measured using histological grade and tumour type. Histological grade, which measures the similarity to the TDLUs, reflects the degree of differentiation whereas tumour type reflects the type of differentiation. Understanding BC phenotypic differentiation facilitates the accurate diagnosis and histological classification of BC with corresponding clinical implications in terms of disease behaviour, prognosis and management plans. In this review, we highlight the potential pathways that BC stem cells follow resulting in the development of different histological types of BC and how knowledge of these pathways impacts our ability to classify BC in diagnostic practice. We also discuss the role of cellular differentiation in producing metaplastic and neuroendocrine carcinomas of the breast and how the latter differ from their counterparts in other organs, with emphasis on clinical relevance.

Metastatic "Ductal Carcinoma In Situ-Like" Lobular Carcinoma in a Lymph Node: A Case Report and Review of the Literature

Metastatic breast cancer resembling ductal carcinoma in situ (DCIS) is a rare phenomenon. In this article, we present a unique case of metastatic lobular carcinoma with DCIS-like morphology in the left axillary lymph nodes of a 52-year-old female. She presented with 2 lesions in the left breast on mammography, and a mastectomy with axillary lymph node dissection was performed. Gross examination showed a 3.5 × 2.5 × 1.0 cm indistinct tumor in the lower outer quadrant and a 2.5 × 2.5 × 1.8 cm tumor in the upper outer quadrant. Microscopic assessment revealed a pleomorphic lobular carcinoma in the lower outer quadrant and a grade 2 invasive ductal carcinoma in the upper outer quadrant. Sixteen of the 17 axillary lymph nodes showed metastatic lobular carcinoma with foci of solid and comedo-type DCIS-like features. Immunohistochemical analysis of the primary and metastatic lobular carcinoma showed no expression of E-cadherin and p63 antibodies. To our knowledge, metastatic lobular carcinoma exhibiting this pattern has not been reported. The case suggests that lobular carcinoma can morphologically recreate a primary microenvironment at a distant site and simulate in situ growth. Recognition of this pattern is important to avoid misdiagnosis.

Histopathological growth patterns as a candidate biomarker for immunomodulatory therapy

The encroachment of a growing tumor upon the cells and structures of surrounding normal tissue results in a series of histopathological growth patterns (HGPs). These morphological changes can be assessed in hematoxylin-and-eosin (H&E) stained tissue sections from primary and metastatic tumors and have been characterized in a range of tissue types including liver, lung, lymph node and skin. HGPs in different tissues share certain general characteristics like the extent of angiogenesis, but also appropriate tissue-specific mechanisms which ultimately determine differences in the biology of HGP subtypes. For instance, in the well-characterized HGPs of liver metastases, the two main subtypes, replacement and desmoplastic, recapitulate two responses of the normal liver to injury: regeneration and fibrosis. HGP subtypes have distinct cytokine profiles and differing levels of lymphocytic infiltration which suggests that they are indicative of immune status in the tumor microenvironment. HGPs predict response to bevacizumab and are associated with overall survival (OS) after surgery for liver metastases in colorectal cancer (CRC). In addition, HGPs can change over time in response to therapy. With standard scoring methods being developed, HGPs represent an easily accessible, dynamic biomarker to consider when determining strategies for treatment using anti-VEGF and immunomodulatory drugs.

International consensus guidelines for scoring the histopathological growth patterns of liver metastasis

Background:

Liver metastases present with distinct histopathological growth patterns (HGPs), including the desmoplastic, pushing and replacement HGPs and two rarer HGPs. The HGPs are defined owing to the distinct interface between the cancer cells and the adjacent normal liver parenchyma that is present in each pattern and can be scored from standard haematoxylin-and-eosin-stained (H&E) tissue sections. The current study provides consensus guidelines for scoring these HGPs.

Methods:

Guidelines for defining the HGPs were established by a large international team. To assess the validity of these guidelines, 12 independent observers scored a set of 159 liver metastases and interobserver variability was measured. In an independent cohort of 374 patients with colorectal liver metastases (CRCLM), the impact of HGPs on overall survival after hepatectomy was determined.

Results:

Good-to-excellent correlations (intraclass correlation coefficient >0.5) with the gold standard were obtained for the assessment of the replacement HGP and desmoplastic HGP. Overall survival was significantly superior in the desmoplastic HGP subgroup compared with the replacement or pushing HGP subgroup (P=0.006).

Conclusions:

The current guidelines allow for reproducible determination of liver metastasis HGPs. As HGPs impact overall survival after surgery for CRCLM, they may serve as a novel biomarker for individualised therapies.

Solid Papillary Breast Carcinomas Resembling the Tall Cell Variant of Papillary Thyroid Neoplasms: A Unique Invasive Tumor With Indolent Behavior

Thirteen cases of invasive solid papillary breast carcinomas resembling the tall cell variant of papillary thyroid neoplasms (BPTC) are reported here. Some cases had long-term follow-up. BPTC is a special type of primary breast neoplasm showing a triple-negative profile but low aggressive potential. Knowledge on BPTC is still scanty; therefore, the aim of the present paper was to report on the features of an additional 13 cases. All the patients were female individuals, and the mean age at presentation was 62.6 years; nodule sizes ranged from 0.6 to 2.5 cm (average, 1.6 cm). All the cases were characterized on histology by papillary, follicular as well as solid structures. The cells were columnar, eosinophilic mostly with granular cytoplasms, rich in mitochondria, with the features of oncocytes in no fewer than 7 cases. Estrogen and progesterone receptors as well as HER2 were consistently negative. The Ki67 proliferative index was low. Markers consistent with thyroid origin, such as TTF1 and thyroglobulin, were negative. Five cases stained for mammoglobin and GATA 3 were positive. All cases proved to be invasive and 2 cases each experienced metastases to 1 lymph node (axillary and intramammary). One case of the latter had a local recurrence. Nevertheless, all the patients are alive, free of disease 24 to 132 months after surgery, of which 8 are without further treatment The present series confirms that BPTC is a primary breast tumor of low malignant potential.

The Opportunity of Precision Medicine for Breast Cancer With Context-Sensitive Tumor Suppressor Maspin

To improve the precision of molecular diagnosis and to develop and guide targeted therapies of breast cancer, it is essential to determine the mechanisms that underlie the specific tumor phenotypes. To this end, the application of a snapshot of gene expression profile for breast cancer diagnosis and prognosis is fundamentally challenged since the tissue-based data are derived from heterogonous cell types and are not likely to reflect the dynamics of context-dependent tumor progression and drug sensitivity. The intricate network of epithelial differentiation program can be concertedly controlled by tumor suppressor maspin, a homologue of clade B serine protease inhibitors (serpin), through its multifaceted molecular interactions in multiple subcellular localizations. Unlike most other serpins that are expressed in multiple cell types, maspin is epithelial specific and has distinct roles in luminal and myoepithelial cells. Endogenously expressed maspin has been found in the nucleus and cytoplasm, and detected on the surface of cell membrane. It is also secreted free and as an exosomal cargo protein. Research in the field has led to the identification of the maspin targets and maspin-associated molecules, as well as the structural determinants of its suppressive functions. The current review discusses the possibility for maspin to serve as a cell type-specific and context-sensitive marker to improve the precision of breast cancer diagnosis and prognosis. These advancements further suggest a new window of opportunity for designing novel maspin-based chemotherapeutic agents with improved anti-cancer potency. J. Cell. Biochem. 118: 1639-1647, 2017. © 2017 Wiley Periodicals, Inc.

Maspin Expression in Prostate Tumor Cells Averts Stemness and Stratifies Drug Sensitivity

Future curative cancer chemotherapies have to overcome tumor cell heterogeneity and plasticity. To test the hypothesis that the tumor suppressor maspin may reduce microenvironment-dependent prostate tumor cell plasticity and thereby modulate drug sensitivity, we established a new schematic combination of two-dimensional (2D), three-dimensional (3D), and suspension cultures to enrich prostate cancer cell subpopulations with distinct differentiation potentials. We report here that depending on the level of maspin expression, tumor cells in suspension and 3D collagen I manifest the phenotypes of stem-like and dormant tumor cell populations, respectively. In suspension, the surviving maspin-expressing tumor cells lost the self-renewal capacity, underwent senescence, lost the ability to dedifferentiate in vitro, and failed to generate tumors in vivo. Maspin-nonexpressing tumor cells that survived the suspension culture in compact tumorspheres displayed a higher level of stem cell marker expression, maintained the self-renewal capacity, formed tumorspheres in 3D matrices in vitro, and were tumorigenic in vivo. The drug sensitivities of the distinct cell subpopulations depend on the drug target and the differentiation state of the cells. In 2D, docetaxel, MS275, and salinomycin were all cytotoxic. In suspension, while MS275 and salinomycin were toxic, docetaxel showed no effect. Interestingly, cells adapted to 3D collagen I were only responsive to salinomycin. Maspin expression correlated with higher sensitivity to MS275 in both 2D and suspension and to salinomycin in 2D and 3D collagen I. Our data suggest that maspin reduces prostate tumor cell plasticity and enhances tumor sensitivity to salinomycin, which may hold promise in overcoming tumor cell heterogeneity and plasticity.

Tumor suppressor maspin as a rheostat in HDAC regulation to achieve the fine-tuning of epithelial homeostasis

Maspin, a class II tumor suppressor, is often downregulated during tumor progression and its depletion from the nucleus is associated with poor prognosis. Recently, we reported that reintroduction of maspin is sufficient for redifferentiation of prostate cancer cells to epithelial phenotype, a reversal of epithelial-to-mesenchymal transition. We have linked this effect of maspin with its ability to directly inhibit HDAC1, thereby influencing the acetylation state of transcription factors and other proteins. Maspin overexpression leads to changes in the expression level of a large number of proteins and these changes are often microenvironment specific. In this review, we summarize the epigenetic effects of maspin and provide comprehensive bioinformatic analysis of microarray-derived gene expression changes caused by maspin in different microenvironments. The analysis was performed on multiple levels, including identification of statistically enriched gene ontology groups, detection of overreprepresented transcription factors binding sites in promoters of differentially expressed genes, followed by searching for key nodes of regulatory networks controlling these transcription factors. The results are consistent with our hypothesis that maspin serves as an endogenous regulator of HDAC activity and suggest that the effect of maspin is primarily mediated by TGFβ, β-catenin/E-cadherin pathways, and network key nodes such as Abl kinase, p62, IL1, and caspases 6 and 8.

Metastatic mammary carcinoma with DCIS-like morphology: a report of two cases

Two cases of breast carcinoma with lymph node metastases are presented. In each case the metastases demonstrated the unusual phenomenon of resembling either cribriform or comedo DCIS. Furthermore both cases had the additional rare feature of demonstrable lymphatic involvement by DCIS-like carcinoma.

Dormant but migratory tumour cells in desmoplastic stroma of invasive ductal carcinomas

Mortality in breast cancer is linked to metastasis and recurrence yet there is no acceptable biological model for cancer relapse. We hypothesise that there might exist primary tumour cells capable of escaping surgery by migration and resisting radiotherapy and chemotherapy to cause cancer recurrence. We investigated this possibility in invasive ductal carcinoma (IDC) tissue and observed the presence of solitary primary tumour cells (SPCs) in the dense collagen stroma that encapsulates intratumoural cells (ICs). In IDC tissue sections, collagen was detected with either Masson's Trichrome or by second harmonics imaging. Cytokeratin-19 (CK-19) and vimentin (VIM) antibodies were, respectively, used to identify epithelial-derived tumour cells and to indicate epithelial to mesenchymal transition (EMT). Confocal/multiphoton microscopy showed that ICs from acini were mainly CK-19(+ve) and were encapsulated by dense stromal collagen. Within the stroma, SPCs were detected by their staining for both CK-19 and VIM (confirming EMT). ICs and SPCs were subsequently isolated by laser capture microdissection followed by multiplex tandem-PCR studies. SPCs were found to be enriched for pro-migratory and anti-proliferative genes relative to ICs. In vitro experiments using collagen matrices at 20 mg/cm(3), similar in density to tumour matrices, demonstrated that SPC-like cells were highly migratory but dormant, phenotypes that recapitulated the genotypes of SPCs in clinical tissue. These data suggest that SPCs located at the breast cancer perimeter are invasive and dormant such that they may exceed surgical margins and resist local and adjuvant therapies. This study has important connotations for a role of SPCs in local recurrence.

Maspin reprograms the gene expression profile of prostate carcinoma cells for differentiation

Maspin is an epithelial-specific tumor suppressor gene. Previous data suggest that maspin expression may redirect poorly differentiated tumor cells to better differentiated phenotypes. Further, maspin is the first and only endogenous polypeptide inhibitor of histone deacetylase 1 (HDAC1) identified thus far. In the current study, to address what central program of tumor cell redifferentiation is regulated by maspin and how tumor microenvironments further define the effects of maspin, we conducted a systematic and extensive comparison of prostate tumor cells grown in 2-dimensional culture, in 3-dimensional collagen I culture, and as in vivo bone tumors. We showed that maspin was sufficient to drive prostate tumor cells through a spectrum of temporally and spatially polarized cellular processes of redifferentiation, a reversal of epithelial-to-mesenchymal transition (EMT). Genes commonly regulated by maspin were a small subset of HDAC target genes that are closely associated with epithelial differentiation and TGFβ signaling. These results suggest that a specific endogenous HDAC inhibitor may regulate one functionally related subset of HDAC target genes, although additional maspin-induced changes of gene expression may result from tumor interaction with its specific microenvironments. Currently, EMT is recognized as a critical step in tumor progression. To this end, our current study uncovered a link between maspin and a specific mechanism of prostate epithelial differentiation that can reverse EMT.

Breast carcinomatous tumoral emboli can result from encircling lymphovasculogenesis rather than lymphovascular invasion

The canonical view of the origin of tumor lymphovascular emboli is that they usually originate from lymphovascular invasion as part of a multistep metastatic process. Recent experimental evidence has suggested that metastasis can occur earlier than previously thought and we found evidence that tumor emboli formation can result from the short-circuiting step of encircling lymphovasculogenesis. Experimentally, we used a xenograft of human inflammatory breast cancer (MARY-X), a model that exhibited florid tumor emboli, to generate tumoral spheroids in vitro. In observational studies, we chose human breast carcinoma cases where there appeared to be a possible transition of in situ carcinoma to lymphovascular emboli without intervening stromal invasion. These cases were studied by morphometry as well as IHC with tumor proliferation (Ki-67) and adhesion (E-cadherin) markers, myoepithelial (p63), as well as endothelial (podoplanin [D2-40], CD31, VEGFR-3, Prox-1) markers. Unlabelled spheroids coinjected with either GFP or RFP-human myoepithelial cells or murine embryonal fibroblasts (MEFs) gave rise to tumors which exhibited GFP/RFP immunoreactivity within the cells lining the emboli-containing lymphovascular channels. In vitro studies demonstrated that the tumoral spheroids induced endothelial differentiation of cocultured myoepithelial cells and MEFs, measured by real time PCR and immunofluorescence. In humans, the in situ clusters exhibited similar proliferation, E-cadherin immunoreactivity and size as the tumor emboli (p =.5), suggesting the possibility that the latter originated from the former. The in situclusters exhibited a loss (50%-100%) of p63 myoepithelial immunoreactivity but not E-cadherin epithelial immunoreactivity. The tumor emboli were mainly present within lymphatic channels whose dual p63/CD31, p63/D2-40 and p63/VEGFR-3 and overall weak patterns of D2-40/CD31/VEGFR-3 immunoreactivities suggested that they represented immature and newly created vasculature derived from originally myoepithelial-lined ducts. Collectively both experimental as well as observational studies suggested the possibility that these breast cancer emboli resulted from encircling lymphovasculogenesis rather than conventional lymphovascular invasion.

Metaplastic breast carcinoma: tumour histogenesis or dedifferentiation?

Global gene expression profiling studies have classified breast cancer into molecular classes, some of which show similarity to normal mammary cells (ie luminal and basal subtypes) with a subsequent histogenetic implication that reinforced the perception that the phenotype of breast cancer reflects the cell of origin. However, it remains to be determined whether phenotypic changes are the result of malignant transformation of particular cancer stem cells (histogenesis) or specific genetic hits occurring at various stages of carcinogenesis (dedifferentiation). We sought to test the hypothesis that dedifferentiation may be the more likely explanation using in vivo clinical data. Our findings support the hypothesis that at least some metaplastic carcinomas are derived from phenotypic transition from conventional mammary adenocarcinoma either at the in-situ, primary invasive stage or at a distant metastatic site. This observation argues against the cell of origin theory (histogenesis) for breast carcinogenesis and favours the concept of tumour dedifferentiation at later stages.

Breast carcinomatous tumoral emboli can result from encircling lymphovasculogenesis rather than lymphovascular invasion

The canonical view of the origin of tumor lymphovascular emboli is that they usually originate from lymphovascular invasion as part of a multistep metastatic process. Recent experimental evidence has suggested that metastasis can occur earlier than previously thought and we found evidence that tumor emboli formation can result from the short-circuiting step of encircling lymphovasculogenesis. Experimentally, we used a xenograft of human inflammatory breast cancer (MARY-X), a model that exhibited florid tumor emboli, to generate tumoral spheroids in vitro. In observational studies, we chose human breast carcinoma cases where there appeared to be a possible transition of in situ carcinoma to lymphovascular emboli without intervening stromal invasion. These cases were studied by morphometry as well as IHC with tumor proliferation (Ki-67) and adhesion (E-cadherin) markers, myoepithelial (p63), as well as endothelial (podoplanin [D2-40], CD31, VEGFR-3, Prox-1) markers. Unlabelled spheroids coinjected with either GFP or RFP-human myoepithelial cells or murine embryonal fibroblasts (MEFs) gave rise to tumors which exhibited GFP/RFP immunoreactivity within the cells lining the emboli-containing lymphovascular channels. In vitro studies demonstrated that the tumoral spheroids induced endothelial differentiation of cocultured myoepithelial cells and MEFs, measured by real time PCR and immunofluorescence. In humans, the in situ clusters exhibited similar proliferation, E-cadherin immunoreactivity and size as the tumor emboli (p =.5), suggesting the possibility that the latter originated from the former. The in situclusters exhibited a loss (50%-100%) of p63 myoepithelial immunoreactivity but not E-cadherin epithelial immunoreactivity. The tumor emboli were mainly present within lymphatic channels whose dual p63/CD31, p63/D2-40 and p63/VEGFR-3 and overall weak patterns of D2-40/CD31/VEGFR-3 immunoreactivities suggested that they represented immature and newly created vasculature derived from originally myoepithelial-lined ducts. Collectively both experimental as well as observational studies suggested the possibility that these breast cancer emboli resulted from encircling lymphovasculogenesis rather than conventional lymphovascular invasion.

A role of novel serpin maspin in tumor progression: the divergence revealed through efforts to converge

Maspin, a 42 kDa protein, belongs to the serine protease inhibitor (serpin) superfamily and is more closely related to the ovalbumin-like serpin subfamily (ov-serpins). More than a decade after the discovery of the maspin gene, our pursuit of the molecular mechanisms of maspin revealed a significant divergence of maspin from other serpins. This review article summarizes recent advances in the identification of maspin-binding proteins and the potential underlying molecular mechanisms of maspin in tumor progression. Specifically, the molecular interactions of maspin with the cell surface-associated pro-urokinase-type plasminogen activator (pro-uPA) and intracellular histone deacetylase 1 (HDAC1) are highlighted. Our new evidence suggests a new paradigm that maspin acts as a serpin-like molecule to inhibit serine protease-like targets. From an evolution point of view, the uniquely important function of maspin in development and tumor progression is likely due to its ancestral sequence code, and accordingly, its novel "meta"-serpin structure. It is reasonable to hypothesize that the conservation of a serine protease-like catalytic center in many molecules requires the co-existence of endogenous antagonists. The unique inhibitory interaction of maspin with both HDAC1 and pro-uPA might not be substituted by other serpins that have evolved to acquire higher target specificities. Thus, tumor suppressive maspin offers a unique therapeutic opportunity.

Benign glandular inclusions a rare cause of a false positive sentinel node

An 84-year-old female underwent a wire-guided lumpectomy and sentinel lymph node biopsy. Two sentinel nodes were identified and sent for immediate pathological evaluation. One of the nodes was reported as "glandular epithelium consistent with metastatic adenocarcinoma." Permanent sections of the sentinel node initially considered positive revealed glandular structures primarily within the fibrous capsule of the involved lymph node. These glands were lined by tall columnar epithelial cells, which had cilia on the luminal surface and did not show significant cytologic atypia. The limitations of intra-operative evaluation of sentinel nodes make differentiation of uncommon pathology difficult. A conservative approach should be taken with these lesions as permanent sections will often elucidate the diagnosis.

Tumor suppressive maspin and epithelial homeostasis

Maspin is a 42-kDa novel serine protease inhibitor (serpin) with multifaceted tumor suppressive activities. To date, the consensus that maspin expression predicts a better prognosis still largely holds for breast, prostate, colon, and oral squamous cancers. Interestingly, however, more detailed analyses revealed a biphasic expression pattern of maspin in early steps of tumorigenicity and re-expression of maspin in dormant cancer metastatic revertants. These data suggest a sensitivity of maspin expression to changes of epithelial microenvironments, and a role of maspin in epithelial homeostasis. Experimental evidence consistently showed that maspin suppresses tumor growth, invasion and metastasis, induces tumor redifferentiation, and enhances tumor cell sensitivity to apoptosis. Maspin protein isolated from biological sources is a monomer, which is present as a secreted, a cytoplasmic, a nuclear, as well as a cell surface-associated protein. Nuclear maspin is associated with better prognoses of cancer. It is further noted that extracellular maspin is sufficient to block tumor induced extracellular matrix degradation, tumor cell motility and invasion, whereas intracellular maspin is responsible for the increased cellular sensitivity to apoptosis. Despite these exciting developments, the mechanistic studies of maspin have proven challenging primarily due to the lack of a prototype molecular model. Although the maspin sequence has overall homologies with other members in the serpin superfamily, it does not behave like a typical serpin, that is, non-inhibitory toward active serine proteases in solution. This novel feature is in line with the X-ray crystallographic evidence. Several recent studies dedicated to finding the maspin partners support a paradigm shift. The current review is intended to summarize these recent findings and discuss a new perspective of maspin in epithelial homeostasis.

Do myoepithelial cells hold the key for breast tumor progression?

Mammary myoepithelial cells have been a neglected facet of breast cancer biology, largely ignored since they have been considered to be less important for tumorigenesis than luminal epithelial cells from which most of breast carcinomas are thought to arise. In recent years as our knowledge of stem cell biology and the cellular microenvironment has been increasing, myoepithelial cells are slowly starting to gain more attention. Emerging data raise the hypothesis whether myoepithelial cells play a key role in breast tumor progression by regulating the in situ to invasive carcinoma transition and that myoepithelial cells are part of the mammary stem cell niche. Paracrine interactions between myoepithelial and luminal epithelial cells are known to be important for regulation of cell cycle progression, establishing epithelial cell polarity, and inhibiting cell migration and invasion. Based on these functions, normal mammary myoepithelial cells have been called "natural tumor suppressors." However, during tumor progression myoepithelial cells seem to loose these properties, and eventually this cell population diminishes as tumors become invasive. Better understanding of myoepithelial cell function and their role in tumor progression may lead to their exploitation for cancer therapeutic and preventative measures.

Ductal carcinoma in situ-like structures in metastatic breast carcinoma

In this report, we present two cases of axillary lymph node metastatic breast carcinoma with features mimicking ductal carcinoma in situ (DCIS): one was of the comedo-like type and the other was suggestive of the micropapillary type. In the first case, the primary tumor presented DCIS of the comedo type; however, in the second case, the primary tumor consisted only of the invasive ductal component. Immunohistochemistry against smooth muscle actin, S100-protein, CK5/6, CD10, P63, and 34betaE12 did not identify myoepithelial cells either in DICS of the first primary tumor or in both metastases. These features probably do not represent the true DCISs, but only mimic them. This observation suggests that a proportion of "primary DCIS" may constitute an invasive pseudo-DCIS carcinoma, and immunohistochemical identification of myoepithelial cells may be helpful in such cases.

Hepsin and maspin are inversely expressed in laser capture microdissectioned prostate cancer

PURPOSE

Recent studies have shown that hepsin, a serine protease, is over expressed in prostate cancers, implicating hepsin activity in tumor invasion. Using microarray technology we have previously identified 22 genes that were up-regulated in high grade prostate cancers compared with benign prostatic hyperplasia. Of them hepsin was the most differentially over expressed. In the current report we compare hepsin to maspin (BD Transduction Laboratories, San Diego, California), a serine protease inhibitor (serpin), to measure the balance between levels of serine proteases and serpins, which are considered to be a critical determinant of net proteolytic activity.

MATERIALS AND METHODS

We combined the technique of laser capture microdissection with gene expression monitoring by micro-array analysis to investigate the gene expression profiles of prostate cells of different histological types. We also studied maspin immunohistochemically.

RESULTS

We observed that hepsin as well as 7 of 22 previously reported up-regulated genes demonstrated a pattern of increasing expression with increasing malignant phenotype. In contrast, the expression of maspin (a serpin) decreased with increasing malignancy of prostate cancers. Using immunohistochemistry we observed that maspin protein is expressed strongly in benign prostatic tissues and slightly in grade 3 prostate cancers, and is absent in grade 4/5 cancers.

CONCLUSIONS

We conclude that the increased ratio of hepsin-to-maspin may have an important role in prostate cancer progression and invasion.

Ectopic breast tissue as a possible cause of false-positive axillary sentinel lymph node biopsies

Epithelial inclusions representing ectopic breast tissue are uncommonly seen in axillary lymph nodes. The extensive histopathologic examination of axillary sentinel lymph nodes of patients with breast carcinoma may increase the chances to encounter tiny foci of ectopic breast tissue, which may be misinterpreted as (micro)metastatic disease and lead to unwarranted completion of axillary dissection and to inaccurate staging and improper adjuvant treatments for the patients. Here we report on seven cases of ectopic breast tissue in axillary sentinel lymph nodes. In three cases there were coexistent micrometastases, and in the remaining cases the ectopic tissue was not associated with metastatic disease. The ectopic breast tissue showed remarkably varied morphologic features, including apocrine metaplasia and proliferative changes indistinguishable from those occurring in sclerosing adenosis and florid epithelial hyperplasia of the breast. A peripheral layer of myoepithelial cells was consistently detected in the ectopic glands and ducts. Besides awareness and purely morphologic criteria, a false-positive identification of these inclusions as metastatic carcinoma may be avoided by the use of immunohistochemical reactions for the localization of specific markers of the myoepithelial cell component, which is associated with the ectopic breast tissue.

A non-Darwinian role for mutagenesis in stem cell-derived cancers

It is clear that mutations cause cancer. The implicated mechanism is Darwinism. That is, a stochastic series of mutations is purported to effect the cellular variability upon which natural selection acts to yield increasingly cancer-like intermediates leading ultimately to malignant clones. It is no wonder then that the neoplastic phenotype is considered "alien," having evolved via random unrehearsed events. Neoplasia, however, has also been depicted as something less than foreign, bordering on familiar. This is because cancer shares proliferative and invasive qualities with the native developmental processes of embryogenesis and adult tissue renewal/repair. A question then arises: If key features of malignancy already naturally exist within well-choreographed programs, why reinvent this phenotype via stochastic multistep schemes rather than reactivate it largely en bloc? Indeed, as will be shown, tissues do harbor a malignant potential capable of reactivation. Specifically, this capability is maintained by stem cells (having inherited such from embryonic precursors)-a phenotype controlled by a microenvironment favoring perpetual rearing by (quiescent) stem cells of proliferative progeny for orderly renewal over neoplasia. Accordingly, normally well-sequestered stem cells, when amid carcinogen/mutagen-induced disruption to local surroundings, produce progeny tending by default toward disorderliness (neoplasia) over renewal. Because such tumor-causing mutations act non-cell autonomously, this cancerous state is potentially reversible but subsequent cell-autonomous mutations can impair particular clonal progeny, already cancerous, from regressing. Thus, a scenario wherein mutations (1) de-repress malignancy non-cell autonomously and then (2) slow its reversion cell autonomously, commonly misinterpreted as Darwinian, may constitute a non-Darwinian mechanism for the genesis of cancers that are stem cell derived.

Association of maspin expression with the high histological grade and lymphocyte-rich stroma in early-stage breast cancer

AIMS

Maspin is a recently described member of the serpin family or protease inhibitors that is known to be a tumour suppressor gene product. Loss of maspin expression has been found in most breast cancer cases and is correlated with cell motility and tumour invasiveness. However, its precise role in human breast cancer remains to be discovered. We aimed to evaluate the role of maspin in early-stage breast cancer.

METHODS AND RESULTS

We analysed the expression of maspin in 192 stage I and II primary breast cancers by immunohistochemistry. Of these cases, 34.4% showed maspin expression. Maspin expression was more frequently found in invasive ductal carcinoma (36.4%) than in invasive lobular carcinoma (7.1%). High maspin expression was demonstrated in breast cancers showing high histological grade or lymphocyte-rich stroma (P < 0.05). Maspin expression was not associated with overall and disease-free survival rate of breast cancer.

CONCLUSIONS

The results indicate that different biological mechanisms may be responsible for maspin expression in histologically distinct types of breast cancer. Our survey suggests that maspin expression in breast cancer might have a compensatory role rather than prognostic one.

"Revertant" mammary solid papillary carcinoma in lymph node metastasis

A case of invasive carcinoma of mixed papillary and not otherwise specified ductal type with areas of solid papillary ductal carcinoma in situ(DCIS) is reported. The solid papillary areas were predominantly of low nuclear grade, but a small area of intermediate-grade solid papillary neoplasm was also seen within the tumor, together with an area suggestive of microinvasion. The massive regional nodal tumor load consisted of invasive papillary carcinoma and revertant low-grade solid papillary carcinoma with no myoepithelial cells around the circumscribed solid papillary areas. This is the first report of a solid papillary pattern simulating intraductal carcinoma in lymph nodes, and the first time that a solid papillary carcinoma is reported in association with invasive papillary carcinoma. The case suggests that mammary carcinomas with a solid papillary pattern may sometimes be of higher grade than usual, and do not always represent a DCIS, but may be invasive.

Molecular mechanisms underlying ErbB2/HER2 action in breast cancer

Overexpression of ErbB2, a receptor-like tyrosine kinase, is shared by several types of human carcinomas. In breast tumors the extent of overexpression has a prognostic value, thus identifying the oncoprotein as a target for therapeutic strategies. Already, antibodies to ErbB2 are used in combination with chemotherapy in the treatment of metastasizing breast cancer. The mechanisms underlying the oncogenic action of ErbB2 involve a complex network in which ErbB2 acts as a ligand-less signaling subunit of three other receptors that directly bind a large repertoire of stroma-derived growth factors. The major partners of ErbB2 in carcinomas are ErbB1 (also called EGFR) and ErbB3, a kinase-defective receptor whose potent mitogenic action is activated in the context of heterodimeric complexes. Why ErbB2-containing heterodimers are relatively oncopotent is a function of a number of processes. Apparently, these heterodimers evade normal inactivation processes, by decreasing the rate of ligand dissociation, internalizing relatively slowly and avoiding the degradative pathway by returning to the cell surface. On the other hand, the heterodimers strongly recruit survival and mitogenic pathways such as the mitogen-activated protein kinases and the phosphatidylinositol 3-kinase. Hyper-activated signaling through the ErbB-signaling network results in dysregulation of the cell cycle homeostatic machinery, with upregulation of active cyclin-D/CDK complexes. Recent data indicate that cell cycle regulators are also linked to chemoresistance in ErbB2-dependent breast carcinoma. Together with D-type cyclins, it seems that the CDK inhibitor p21waf1 plays an important role in evasion from apoptosis. These recent findings herald a preliminary understanding of the output layer which connects elevated ErbB-signaling to oncogenesis and chemoresistance.

Minimal breast cancer: evaluation of histology and biological marker expression

Ninety-eight minimal breast cancers (MBCs) diagnosed between 1975 and 1990, and all originally considered to be invasive were found, on review, to form three groups: (a) 28 predominantly invasive carcinomas < or = 10 mm ('predominant invasive'); (b) 48 predominantly ductal carcinoma in situ (DCIS) lesions with definite foci of invasion each < or = 10 mm ('predominant DCIS'); and (c) 22 DCIS without evidence of invasion ('pure DCIS'). Tumour histology and immunohistochemical expression of Ki-67, c-erbB2, p53, oestrogen receptor (ER), progesterone receptor (PR), and Bcl-2 were compared. The major finding was the contrasting features in the two invasive groups, with significant differences in their extent of invasion (P < 0.0001), tumour grade (P = 0.03), DCIS type (P = 0.008) and in marker expression. In the predominant invasive group, the infiltrative component was usually greater than 5 mm, low-grade and associated with well-differentiated DCIS. Expression of Ki-67, c-erbB2 and p53 was generally low, and that of ER, PR and Bcl-2 high. The predominant DCIS group in contrast had a much smaller, commonly high-grade, invasive component, usually with poorly differentiated DCIS and the reverse pattern of marker expression. Although not significant, survival of patients in the predominant invasive group was slightly better. These findings suggest that invasive MBCs should perhaps be treated as separate entities, in order to aid more appropriate selection of treatment.

Epithelial inclusion in axillary lymph node associated with a breast carcinoma: report of a case with a review of the literature

Since epithelial inclusions in axillary lymph nodes are rare, some diagnostic problems concerning their nature have arisen. We report a case of a cystic squamous epithelial inclusion in an axillary lymph node of a patient affected by a high grade breast carcinoma with focal squamous differentiation. Although the lesion was histologically benign, the possibility that it represents a well-differentiated squamous metastasis cannot be completely ruled out. To our knowledge, this is the first case of an epithelial lymph node inclusion associated with a breast carcinoma showing morphological evidence of squamous differentiation. Here, we discuss the diagnostic problems and give a review of the literature.

Plasticity of mammary epithelia during normal development and neoplastic progression

The functional unit of the mammary gland is the epithelium. It consists of luminal epithelial cells and myoepithelial cells that are generated from self-renewing stem and progenitor cells. The latter two cell types are scattered throughout the mammary epithelium and are concentrated in specialized structures, the end buds. In transplantation studies the pluripotency of mammary stem cells has been confirmed by demonstrating that they can regenerate a complete mammary gland. The ability of mammary epithelial cells to produce an elaborate ductal system during puberty and to differentiate into milk-producing alveoli during pregnancy is not only influenced by their genetic make-up, but is also governed by local molecular signals. Recent studies suggest that the transdifferentiation of epithelial cells into tumor cells is under microenvironmental control, despite the prominence of genetic mutations in breast cancer. Consequently, disturbances of tissue homeostasis can alter mammary gland development or result in preneoplastic and neoplastic pathologies. The plasticity of mammary epithelia is not limited to the entry of cells into differentiation and transdifferentiation pathways, but extends to their ability to regain facets of their preceding stage of functionality. Deciphering the molecular cues that determine cell plasticity is prerequisite for establishing a unifying concept of mammary gland development and breast tumor progression.Key words: branching morphogenesis, lactogenic differentiation, stem cells, epithelial-to-mesenchymal transition, cancer.

Molecular assessment of tumour stage and disease recurrence using PCR-based assays

Solid cancers arise as a consequence of the accumulation of genetic and epigenetic alterations within a single cell or group of cells. Their ongoing characterization is providing a range of acid-based molecular markers for neoplasia. This, together with continuous refinements to the polymerase chain reaction (PCR), had led to the emergence of PCR-based assays as potential aids in the clinical management of cancer patients. Although the sensitivity of molecular diagnosis has the potential to aid clinicians in therapeutic decision making, problems with its specificity mean that the predictive value of molecular staging is still unproved. Its role in the identification of minimal residual disease after curative surgical resection requires clinical validation in further prospective studies.