Metaplastic carcinoma of the breast: p53 analysis identified the same point mutation in the three histologic components

Transcriptomic alterations underlying metaplasia into specific metaplastic components in metaplastic breast carcinoma

BACKGROUND

Metaplastic breast carcinoma (MpBC) typically consists of carcinoma of no special type (NST) with various metaplastic components. Although previous transcriptomic and proteomic studies have reported subtype-related heterogeneity, the intracase transcriptomic alterations between metaplastic components and paired NST components, which are critical for understanding the pathogenesis underlying the metaplastic processes, remain unclear.

METHODS

Fifty-nine NST components and paired metaplastic components (spindle carcinomatous [SPS], matrix-producing, rhabdoid [RHA], and squamous carcinomatous [SQC] components) were microdissected from specimens obtained from 27 patients with MpBC for gene expression profiling using the NanoString Breast Cancer 360 Panel on a NanoString nCounter FLEX platform. BC360-defined signatures were scored using nSolver software.

RESULTS

Hierarchical clustering and principal component analysis revealed a heterogeneous gene expression profile (GEP) corresponding to the NST components, but the GEP of metaplastic components exhibited subtype dependence. Compared with the paired NST components, the SPS components demonstrated the upregulation of genes related to stem cells and epithelial-mesenchymal transition and displayed enrichment in claudin-low and macrophage signatures. Despite certain overlaps in the enriched functions and signatures between the RHA and SPS components, the specific differentially expressed genes differed. We observed the RHA-specific upregulation of genes associated with vascular endothelial growth factor signaling. The chondroid matrix-producing components demonstrated the upregulation of hypoxia-related genes and the downregulation of the immune-related MHC2 signature and the TIGIT gene. In the SQC components, TGF-β and genes associated with cell adhesion were upregulated. The differentially expressed genes among metaplastic components in the 22 MpBC cases with one or predominantly one metaplastic component clustered paired NST samples into clusters with correlation with their associated metaplastic types. These genes could be used to separate the 31 metaplastic components according to respective metaplastic types with an accuracy of 74.2%, suggesting that intrinsic signatures of NST may determine paired metaplastic type. Finally, the EMT activity and stem cell traits in the NST components were correlated with specimens displaying lymph node metastasis.

CONCLUSIONS

We presented the distinct transcriptomic alterations underlying metaplasia into specific metaplastic components in MpBCs, which contributes to the understanding of the pathogenesis underlying morphologically distinct metaplasia in MpBCs.

Clinicopathological Examination of Metaplastic Spindle Cell Carcinoma of the Breast: Case Series

Background:

Spindle cell carcinoma (SpCC) of the breast is a rare histological type, a subtype of metaplastic carcinoma characterized by atypical spindle cell and epithelial carcinoma. The proportions of the spindle cell and epithelial components vary among tumours. Due to its rarity, biological characteristics of this disease have been poorly studied.

Methods:

In total, 10 patients with SpCC were surgically treated at our institution from January 2007 to December 2018. We retrospectively investigated these SpCC cases, focusing on the differences between spindle cell and epithelial components. Microsatellite status was also examined.

Results:

Nine cases were triple-negative breast cancer (TNBC). The rates of high tumour grade were 70% in spindle cell components and 56% in epithelial components (P = .65), while the mean Ki67 labelling index were 63% and 58%, respectively (P = .71). Mean programmed death ligand 1 (PD-L1) expression in these components was 11% and 1%, respectively (P = .20). All 10 tumours were microsatellite stable. Patient outcomes of triple-negative SpCC did not differ from those of propensity-matched patients with conventional TNBC.

Conclusions:

Spindle cell components showed higher values in factors examined, although there was no statistically significant difference. Our data reveal that these 2 components of SpCC may be of different biological nature.

Spindle cell lesions of the breast: a diagnostic approach

Spindle cell lesions of the breast comprise a heterogeneous group of lesions, ranging from reactive and benign processes to aggressive malignant tumours. Despite their rarity, they attract the attention of breast pathologists due to their overlapping morphological features and diagnostic challenges, particularly on core needle biopsy (CNB) specimens. Pathologists should recognise the wide range of differential diagnoses and be familiar with the diverse morphological appearances of these lesions to make an accurate diagnosis and to suggest proper management of the patients. Clinical history, immunohistochemistry, and molecular assays are helpful in making a correct diagnosis in morphologically challenging cases. In this review, we present our approach for the diagnosis of breast spindle cell lesions, highlighting the main features of each entity and the potential pitfalls, particularly on CNB. Breast spindle cell lesions are generally classified into two main categories: bland-appearing and malignant-appearing lesions. Each category includes a distinct list of differential diagnoses and a panel of immunohistochemical markers. In bland-appearing lesions, it is important to distinguish fibromatosis-like spindle cell metaplastic breast carcinoma from other benign entities and to distinguish fibromatosis from scar tissue. The malignant-appearing category includes spindle cell metaplastic carcinoma, stroma rich malignant phyllodes tumour, other primary and metastatic malignant spindle cell tumours of the breast, including angiosarcoma and melanoma, and benign mimics such as florid granulation tissue and nodular fasciitis.

Metaplastic carcinomas of the breast without evidence of epithelial differentiation: a diagnostic approach for management

AIMS

Although rare, malignant sarcomatoid breast tumours without evidence of epithelial differentiation comprise a diagnostic challenge with management implications. Earlier studies have generally considered these to be primary breast sarcomas; however, supporting evidence is lacking and management remains variable. This study aimed to provide an evidence-based approach to improve the consistency of diagnosis and management for such cases.

METHODS AND RESULTS

A large series (n = 140) of metaplastic breast carcinoma (MBC) diagnosed in Nottingham over 18 years was analysed. Only cases with available data on immunohistochemical expression of cytokeratins (CKs) were included. The prevalence and pattern of expression for various CKs were assessed and details of tumours negative for CKs were collected. A diagnostic approach based on our experience is provided. Forty-seven cases (34%) showed foci of conventional type invasive breast carcinoma or ductal carcinoma in situ (DCIS), while 93 cases (66%) were diagnosed as MBC based on morphology and/or CK expression. Ninety-seven cases (69%) were negative for one or more CKs, with 18 cases (13%) negative for five or more CKs. Eight cases (6%) lacked expression of all CKs tested. Further examination showed evidence of carcinomatous nature in five cases, and three were diagnosed as MBC following extensive diagnostic work-up and based on our experience.

CONCLUSION

This study suggests that MBC represents a spectrum of neoplasms, with some lacking CK expression. Sarcomatoid neoplasms of the breast lacking evidence of carcinomatous morphology and CK expression may represent an extreme end of differentiation that can be considered as carcinomas rather than sarcomas for management purposes (following extensive work-up).

A Comparative Review of Mixed Mammary Tumors in Mammals

Mixed tumors are characterized by the histological identification of two or more cell types. Commonly, a mixture of epithelial and myoepithelial cells is included in abundant stroma, which can consist of myxoid, chondroid or bony matrices. Spontaneously arising mixed tumors are rare lesions in the human breast but are common in human salivary glands and canine mammary glands. Subtle histopathological characteristics and overlapping attributes of malignant lesions with other benign lesions can lead to a diagnostic challenge. Mixed tumors can present as benign or malignant. While malignant mixed tumors are quite rare in the human breast they have a poor prognosis. Benign mixed mammary tumors occur more frequently in female dogs than in humans and are usually associated with a good prognosis. This review will provide a comprehensive overview of mixed mammary tumors, across various mammalian species.

Genomic profiling of metaplastic breast carcinomas reveals genetic heterogeneity and relationship to ductal carcinoma

Metaplastic breast carcinomas comprise a histologically heterogenous group of tumors. Although most are triple (estrogen/progesterone receptor, HER2) negative, these rare tumors are clinicopathologically distinct from other triple negative carcinomas and may be aggressive with worse chemotherapy responses. On the other hand, metaplastic carcinomas are histologically diverse, which is reflected in gene expression differences among subtypes. Whether metaplastic carcinomas are genetically distinct from other triple negative cancers and whether genetic differences underlie histologic subtypes remains poorly understood. We sequenced 408 cancer-related genes in 28 metaplastic carcinomas, including chondroid matrix-producing carcinomas (n = 10), spindle cell carcinomas (n = 5), and carcinomas with squamous (n = 5), mixed spindle/squamous (n = 5), and mixed metaplastic (n = 3) differentiation. Metaplastic carcinomas were highly enriched for PIK3CA/PIK3R1 (61%) and Ras-Map kinase (25%) pathway aberrations compared to other triple negative carcinomas (TCGA dataset 14%, p < 0.001 and 7%, p = 0.005, respectively) and harbored a high frequency of TP53 (64%) and TERT promoter (25%) mutations, but this varied among subtypes. Chondroid-matrix producing carcinomas lacked PI-3 kinase and Ras-Map kinase aberrations and TERT promoter mutations, compared to 100%, 39%, and 39% of non-matrix-producing tumors, respectively. TERT promoter mutations were enriched (47%) in spindle cell carcinomas and tumors with squamous or spindle/squamous differentiation. Spindle cell carcinomas lacked TP53 mutations, in contrast to other subtypes (78%, p = 0.003). Separate analysis of paired ductal carcinoma in situ and metaplastic carcinoma revealed shared clonality in all cases (n = 8). Activating PI-3 kinase and Ras pathway mutations were early events, and inactivating mutations in tumor suppressors including RB1, CDKN2A, and TP53 were associated with invasion in individual cases. Metaplastic components of two tumors showed genetic progression from separately sequenced paired invasive ductal carcinoma. The findings suggest that metaplastic carcinomas are genetically distinct from other triple negative breast cancers and highlight genetic heterogeneity that broadly correlates with histologic subtype. Heterologous elements progress from associated ductal carcinoma.

Metaplasia: tissue injury adaptation and a precursor to the dysplasia-cancer sequence

Metaplasia is the replacement of one differentiated somatic cell type with another differentiated somatic cell type in the same tissue. Typically, metaplasia is triggered by environmental stimuli, which may act in concert with the deleterious effects of microorganisms and inflammation. The cell of origin for intestinal metaplasia in the oesophagus and stomach and for pancreatic acinar-ductal metaplasia has been posited through genetic mouse models and lineage tracing but has not been identified in other types of metaplasia, such as squamous metaplasia. A hallmark of metaplasia is a change in cellular identity, and this process can be regulated by transcription factors that initiate and/or maintain cellular identity, perhaps in concert with epigenetic reprogramming. Universally, metaplasia is a precursor to low-grade dysplasia, which can culminate in high-grade dysplasia and carcinoma. Improved clinical screening for and surveillance of metaplasia might lead to better prevention or early detection of dysplasia and cancer.

Whole-Exome Sequencing of Metaplastic Breast Carcinoma Indicates Monoclonality with Associated Ductal Carcinoma Component

Purpose: Although most human cancers display a single histology, there are unusual cases where two or more distinct tissue types present within a primary tumor. One such example is metaplastic breast carcinoma, a rare but aggressive cancer with a heterogeneous histology, including squamous, chondroid, and spindle cells. Metaplastic carcinomas often contain an admixed conventional ductal invasive or in situ mammary carcinoma component, and are typically triple-negative for estrogen receptor, progesterone receptor, and HER-2 amplification/overexpression. An unanswered question is the origin of metaplastic breast cancers. While they may arise independently from their ductal components, their close juxtaposition favors a model that postulates a shared origin, either as two derivatives from the same primary cancer or one histology as an outgrowth of the other. Understanding the mechanism of development of these tumors may inform clinical decisions.Experimental Design: We performed exome sequencing for paired metaplastic and adjacent conventional invasive ductal carcinomas in 8 patients and created a pipeline to identify somatic variants and predict their functional impact, without having normal tissue. We then determined the genetic relationships between the histologically distinct compartments.Results: In each case, the tumor components have nearly identical landscapes of somatic mutation, implying that the differing histologies do not derive from genetic clonal divergence.Conclusions: A shared origin for tumors with differing histologies suggests that epigenetic or noncoding changes may mediate the metaplastic phenotype and that alternative therapeutic approaches, including epigenetic therapies, may be required for metaplastic breast cancers. Clin Cancer Res; 23(16); 4875-84. ©2017 AACR.

Diagnosis of Metaplastic Breast Carcinoma: Keratin OSCAR Versus Other Cytokeratins

Metaplastic breast carcinoma (MBC) is a heterogenous group of tumors that diverge from conventional glandular differentiation. The metaplastic component can be focal or may be present purely posing diagnostic challenges. Since MBC may show focal immunostaining or may even be negative for some cytokeratins (CK), different CKs are often needed to prove their epithelial origin. OSCAR is a relatively new broad-spectrum anti-CK antibody. Thirty MBC cases diagnosed at our institution were retrieved, including 7 spindle cell carcinomas. Representative slides were immunostained for CK-OSCAR, CK-AE1/AE3, CAM5.2, CK-903, and CK5/6. Nineteen spindle cell lesions were used as controls, including 6 malignant and 10 borderline phyllodes tumor, 1 inflammatory pseudotumor, 1 solitary fibrous tumor, and 1 nodular fasciitis case. All 30 cases (100%) of metaplastic carcinomas were positive for CK-OSCAR, compared with 27/30 (90%, P=0.076) for CK-AE1/AE3, 21/30 (70%, P≤0.01) for CK-903, 19/30 (63.3%, P≤0.01) for CAM5.2, and 15/30 (50%, P≤0.01) for CK5/6. All control cases were negative for CK-OSCAR. All 7 spindle cell carcinomas were also positive for CK-OSCAR (100%) compared with 6/7 (85.7%) for CK-AE1/AE3, 4/7 (57%) for CK-903, 3/7 (42.8%) for CAM5.2, and 2/7 (28.5%) for CK5/6. Our data show that CK-OSCAR is more sensitive than other individual CKs in diagnosing MBC. Coupled with high specificity, CK-OSCAR may potentially be used in lieu of a panel of CKs to identify the epithelial origin of these tumors, especially in spindle cell tumors. This is particularly useful in limited core biopsy specimens, to help guide treatment and simultaneously lower testing costs.

An approach to the diagnosis of spindle cell lesions of the breast

Although most breast spindle cell lesions (BSCLs) are rare, they constitute a wide spectrum of diseases, ranging from reactive processes to aggressive malignant tumours. Despite their varied histogenesis and behaviour, some lesions show an overlap of morphological features, making accurate diagnosis a challenging task, particularly in needle core biopsies. Clinical history and immunohistochemistry can help in making a correct diagnosis in morphologically challenging cases. To make an accurate diagnosis, it is important to maintain a wide differential diagnosis and be familiar with the diverse morphological appearances of these different entities. BSCLs can generally be classified into bland-looking and malignant-looking categories. In the former, the commonest diagnosis is scarring. However, it is important to distinguish low-grade spindle cell metaplastic breast carcinoma from other benign entities, as the management is clearly different. In the malignant category, it is important to differentiate metaplastic carcinoma from other malignant primary and metastatic malignant spindle cell tumours of the breast, such as malignant phyllodes tumour, angiosarcoma, and melanoma. This review focuses on the classification and histological and molecular diagnosis of various BSCLs, with an emphasis on the diagnostic approach, including in core biopsies.

Breast lesions of uncertain malignant nature and limited metastatic potential: proposals to improve their recognition and clinical management

Breast lesions comprise a family of heterogeneous entities with variable patterns of presentation, morphology and clinical behaviour. The majority of breast lesions are classified traditionally into benign and malignant conditions and their behaviour can, in the vast majority of cases, be predicted with a reasonable degree of accuracy. However, there remain lesions which show borderline features and lie in a grey zone between benign and malignant, as their behaviour cannot be predicted reliably. Defined pathological categorization of such lesions is challenging, and for some entities is recognized to be subjective and include a range of diagnoses, and forms of terminology, which may trigger over- or undertreatment. The rarity of these lesions makes the acquisition of clinical evidence problematic and limits the development of a sufficient evidence base to support informed decision-making by clinicians and patients. Emerging molecular evidence is providing a greater understanding of the biology of these lesions, but this may or may not be reflected in their clinical behaviour. Herein we discuss some breast lesions that are associated with uncertainty regarding classification and behaviour, and hence management. These include biologically invasive malignant lesions associated with uncertain metastatic potential, such as low-grade adenosquamous carcinoma, low-grade fibromatosis-like spindle cell carcinoma and encapsulated papillary carcinoma. Other lesions of uncertain malignant nature remain, such as mammary cylindroma, atypical microglandular adenosis, mammary pleomorphic adenoma and infiltrating epitheliosis. The concept of categories of (1) breast lesions of uncertain malignant nature and (2) breast lesions of limited metastatic potential are proposed with details of which histological entities could be included in each category, and their management implications are discussed.

Prognostic factors in metaplastic carcinoma of the breast: a multi-institutional study

Background:

Metaplastic breast carcinoma (MBC) is a rare type of breast cancer that has basal-like characteristics and is perceived to have poorer prognosis when compared with conventional no specific type/ductal carcinomas (ductal/NST). However, current data on MBC are largely derived from small case series or population-based reports. This study aimed to assess the clinicopathological features and outcome of MBC identified through an international multicentre collaboration.

Methods:

A large international multicentre series of MBC (no=405) with histological confirmation and follow-up information has been included in this study. The prognostic value of different variables and outcome has been assessed and compared with grade, nodal status and ER/HER2 receptor-matched ductal/NST breast carcinoma.

Results:

The outcome of MBC diagnosed in Asian countries was more favourable than those in Western countries. The outcome of MBC is not different from matched ductal/NST carcinoma but the performance of the established prognostic variables in MBC is different. Lymph node stage, lymphovascular invasion and histologic subtype are associated with outcome but tumour size and grade are not. Chemotherapy was associated with longer survival, although this effect was limited to early-stage disease. In this study no association between radiotherapy and outcome was identified. Multivariate analysis of MBC shows that histologic subtype is an independent prognostic feature.

Conclusions:

This study suggests that MBC is a heterogeneous disease. Although the outcome of MBC is not different to matched conventional ductal/NST breast carcinoma, its behaviour is dependent on the particular subtype with spindle cell carcinoma in particular has an aggressive biological behaviour. Management of patients with MBC should be based on validated prognostic variables.

Metaplastic breast cancer: histologic characteristics, prognostic factors and systemic treatment strategies

Metaplastic breast cancer (MBC) is a rare subtype of invasive breast cancer that tends to have an aggressive clinical presentation as well as a variety of distinct histologic designations. Few systemic treatment options are available for MBC, as it has consistently shown a suboptimal response to standard chemotherapy regimens. These characteristics result in a worse overall prognosis for patients with MBC compared to those with standard invasive breast cancer. Due to its rarity, data focusing on MBC is limited. This review will discuss the clinical presentation, breast imaging findings, histologic and molecular characteristics of MBC as well as potential future research directions.

Do primary mammary osteosarcoma and chondrosarcoma exist? A review of a large multi-institutional series of malignant matrix-producing breast tumours

The existing literature describing the clinicopathological features and behaviour of matrix-producing (MP) malignant breast tumours presents conflicting results. As a consequence it remains uncertain whether these tumours should be treated as sarcoma and managed by a specialist sarcoma team or treated using the same principles as conventional ductal carcinoma, a dilemma that prompted this study. Improved understanding of the clinicopathological characteristics of primary mammary MP-sarcomas, namely osteosarcoma and chondrosarcoma, is required.

METHODS

In this large international multicenter series of malignant MP-tumours of the breast (no = 101) with follow-up information has been assessed and their outcome is compared to other subtypes of metaplastic breast carcinoma (MBC) (no = 253) and to grade, lymph node and hormone receptor-matched ductal breast carcinomas (no = 258).

RESULTS

The majority of MP-cancers were associated with epithelial features, which supports the concept that the majority of, if not almost all, primary MP breast sarcomas are of epithelial in origin (MBC). 21% showed nodal metastasis and the distribution of distant metastases resembled conventional mammary carcinoma. The prognosis of MP-MBC is comparable to matched ductal breast carcinoma and slightly better than other subtypes of MBC. Advanced stage (T3&T4) and development of recurrences were predictors of shorter survival in MP-MBC while grade and vascular invasion were not.

CONCLUSION

Most malignant MP breast tumours are variants of MBC. MP-MBC with predominant mesenchymal components behaves similar to ductal carcinomas and although data on their response to systemic therapy is limited, there is no evidence that they should be managed differently from other forms of triple negative breast cancer.

Increased alpha-B-crystallin expression in mammary metaplastic carcinomas

AIMS

 Mammary metaplastic carcinoma is a rare breast carcinoma, and may present diagnostic difficulty. Alpha-B-crystallin has been recently reported to be expressed in basal-like and metaplastic carcinomas.

METHODS AND RESULTS

 Thirty-three metaplastic carcinomas, 44 conventional high-grade carcinomas and 28 mesenchymal spindle cell neoplasms as controls were assessed for their expression of αB-crystallin and conventional basal-like phenotypic markers CK5/6, CK14, p63, c-kit and epidermal growth factor receptor (EGFR) by immunohistochemistry. Alpha-B-crystallin staining was positive in 68% of the metaplastic carcinomas with cytoplasmic staining in all tumour cell components. CK5/6, CK14, p63, c-kit and EGFR stained 43%, 68%, 45%, 21% and 25% of the metaplastic carcinomas, respectively. Combining these markers, 84% of the metaplastic carcinomas expressed either αB-crystallin or CK14. In comparison, only 14% (six cases) of conventional high-grade carcinoma and 7% (two cases) of mesenchymal spindle cell neoplasm expressed αB-crystallin; all but one of these carcinomas were ER/PR/HER2 triple-negative.

CONCLUSIONS

Using αB-crystallin for diagnosis of metaplastic carcinoma gives a 68% sensitivity, 88% specificity, 74% positive predictive value, 85% negative predictive value and 78% accuracy. The sensitivity is enhanced to 84% with combinations of αB-crystallin/CK14. Alpha-B-crystallin may be used as an adjunct marker in the diagnosis of metaplastic carcinoma.

Mixed metaplastic carcinoma of the breast associated with pregnancy: Diagnostic dilemmas in fine-needle aspiration cytology

Metaplastic carcinoma of the breast represents a rare entity characterized by the simultaneous presence of ductal, squamous, and/or mesenchymal components in several proportions. There are limitations in fine-needle aspiration diagnosis due to its pathological heterogeneity. When it develops under pregnancy and lactation influence, the cytologic evaluation appears to be more difficult and accurate diagnosis often proves challenging. We describe a case of mixed metaplastic carcinoma with dominant areas of squamous metaplasia, sarcomatoid stroma with spindle cells, and a minor component of cartilaginous metaplasia. We notify our experience in diagnostic approach of this entity focusing on differential diagnosis.

An assessment of the clonality of the components of canine mixed mammary tumours by mitochondrial DNA analysis

The aim of this study was to investigate if mutations in the mitochondrial DNA (mtDNA) D-loop fragment control region of canine mammary mixed tumours could be used as clonal markers that identified the cell population of origin. Ten benign mixed mammary tumours and nine carcinomas arising from benign mixed tumours were microdissected and DNA from epithelial and mesenchymal tumour cells and from normal mammary tissue was examined for sequence variations in a fragment of the hypervariable control region. Identical sequence variants in both the epithelial and mesenchymal components (as well as in the corresponding normal tissue) were found in 80% of the benign mixed tumours and in 89% of the carcinomas arising from benign mixed tumours suggesting a shared clonal origin. The distinctive sequence alterations identified in the epithelial and mesenchymal components of 15.8% of all 19 tumours examined, suggests the possibility that a minority of mammary tumours are polyclonal in origin or that early clonal divergence occurs. Increased mutation within the mtDNA D-loop fragment of mixed tumour components was not observed.

p63 is useful in the diagnosis of mammary metaplastic carcinomas

AIMS

p63 has been recently reported to be expressed in sarcomatoid/metaplastic carcinoma of the breast, in addition to its role as a myoepithelial marker. A large series of 34 metaplastic carcinomas, including cases with pure epithelial component (squamous cell and adenosquamous carcinomas), biphasic tumours with carcinomatous and sarcomatoid components and monophasic tumours with only spindle cell component, were evaluated for p63 expression with respect to the different cellular components.

METHODS

All of the metaplastic carcinomas were assessed for p63 and conventional epithelial and mesenchymal markers of AE1/3, CAM5.2 and vimentin by immunohistochemistry.

RESULTS

All of the different categories of metaplastic carcinomas showed similar clinico-pathological features (patient age, tumour size, nuclear grade, mitotic activity, lymph node status and hormonal receptor status). For metaplastic carcinoma with epithelial component only, p63 was only expressed in the squamous cell component, but not the adenocarcinoma component. Eight of the 10 tumours were positive for p63. For the tumours with sarcomatoid component, either singly or together with carcinomatous component, p63 was positive in 14 of 24 cases. Pure sarcomas and carcinomas were all negative for p63 staining by immunohistochemistry, thus rendering p63 staining highly specific for diagnosing metaplastic carcinoma.

CONCLUSIONS

Using p63 for diagnosis of metaplastic carcinoma gives a sensitivity of 65%, a specificity of 96%, a positive predictive value of 96%, and a negative predictive value of 66% and an accuracy of 78%. p63 may be used as an adjunct marker in the diagnosis of metaplastic carcinoma.

Fine-needle aspiration cytology of metaplastic carcinoma of the breast

BACKGROUND

Metaplastic carcinoma of the breast encompasses a heterogeneous group of tumours with variable components of sarcomatoid, squamous or poorly differentiated carcinomas.

AIM

To review a series of 19 cytological preparations of metaplastic carcinomas to assess diagnostic cytological features.

METHODS

17 cases of fine-needle aspirates of histologically proven metaplastic carcinomas (4 monophasic spindle cell carcinomas, 4 squamous cell carcinomas and 11 biphasic tumours) were reviewed, with an emphasis on the presence of poorly differentiated carcinoma, squamous cell carcinoma, atypical spindle cells, benign stromal fragments and necrosis.

RESULTS

All cases were diagnosed as malignant, with 68% of cases showing moderate to high cellularity, and 47% showing necrosis. If the tumours were analysed according to the constituting components histologically, 7, 15 and 8 cases, respectively, possess poorly differentiated carcinoma cells, sarcomatoid malignant cells and squamous carcinoma cells, whereas these components were cytologically identified in 11, 10 and 7 cases, respectively. Dual tumour populations were identified in only 5 of the 11 biphasic carcinomas in the cytological preparations; and the stromal material was cytologically identified in the only case with chondroid stroma.

CONCLUSIONS

Identification of metaplastic carcinoma in cytology remains problematic. There seems to be morphological overlap between various components. The identification of dual components, unequivocal squamous carcinoma cells and chondroid stroma is helpful for diagnosis, but it is uncommon. The presence of poorly differentiated carcinoma cells with a suggestion of focal spindle morphology is another clue to the suggestion of metaplastic carcinoma.

Metaplastic breast cancer: clinical significance

BACKGROUND

Metaplastic breast carcinoma (MBC) is a rare poorly differentiated breast cancer characterized by coexistence of ductal carcinoma with areas of matrix producing, spindle-cell, sarcomatous, or squamous differentiation; ER/PR/HER2 negativity; and a reputation for poor outcome.

METHODS

The Swedish Cancer Institute prospective breast cancer database (> 6500 patients; 1990-2005) has 24 MBC cases that were compared with typical breast cancer cases matched for age, date of diagnosis, stage, and ER/PR/HER2 status.

RESULTS

The mean metaplastic primary tumor diameter was 2.5 cm. The histological/nuclear grade was high in 21 of 24 cases. No patient had distant metastasis. ER and/or PR receptor status was negative in all cases. HER2 was negative in 10 of 11 cases tested. EGFR (HER1) was positive in 7 of 7 cases tested. All patients had sentinel and/or axillary lymph node dissection and surgical resection; 18 received chemotherapy and 22 had radiation therapy. Four patients had distant recurrences 5 to 88 months from diagnosis. Five-year survival was 83% (95% confidence interval, 66-100%). Comparison with matched typical breast cancer cases revealed no major significant difference in multidisciplinary treatment patterns, recurrence, or survival.

CONCLUSION

MBC is associated with poor prognostic indicators, but outcomes comparable with matched typical breast cancer cases can be achieved with routine aggressive multidisciplinary care. Increased, expression of EGFR (HER1) provides an opportunity for targeted tumor therapy.

Combined small-cell carcinoma of the stomach: p53 and K-ras gene mutational analysis supports a monoclonal origin of three histological components

Primary small-cell carcinoma (SmCC) is extremely rare in stomach. We reported an autopsy case of combined gastric SmCC with p53 and K-ras mutational analysis. Histologically, the tumour was composed of well-differentiated adenocarcinoma surrounding the central dominant SmCC component with scattered nests of squamous cell carcinoma. Immunohistochemically, all the neoplastic components revealed strong expression for p53 protein. Based on these findings, we hypothesized that these histologically different components originated from a same progenitor cell that possessed p53 mutation. Using Laser-capture microdissection technique and mutational analysis, we identified the same point mutations of p53 gene (A-->G transversion in codon 239) and K-ras gene (G-->A transversion in codon 13) in all the neoplastic components, but not in the adjacent normal gastric epithelium. Our results strongly support a hypothesis that the combined SmCC of stomach in this case was of monoclonal origin.

Squamous cell carcinoma of the larynx with osteosarcoma-like stromal metaplasia

Osseous or chondroid metaplasias are uncommonly found adjacent to laryngeal squamous cell carcinoma (SCC). These findings are less unusual in the spindle cell variant. We describe a moderately differentiated laryngeal SCC associated with osteocartilaginous metaplasia of the adjacent stroma which exhibited very similar morphologic changes and mitoses to an osteosarcoma. These uncommon findings can be more clearly understood if they are viewed as changes determined by the microenvironment of the tumour-host interface, as indicated in recent studies. Tumour cells seem able to regulate stromal development and differentiation via the release of growth factors and the induction of growth factor receptor expression on the cell surface. Irrespective of the limited number of reported cases, the association of SCCs of the larynx with osteocartilaginous metaplasia does not seem to support the adoption of treatments of choice that differ in approach to those for site- and stage-matched SCCs without osteocartilaginous metaplasia.

Metaplastic mammary carcinoma with osteoclast-like giant cells: identical point mutation of p53 gene only identified in both the intraductal and sarcomatous components

Metaplastic mammary carcinoma with osteoclast-like giant cells is a rare neoplasm, and the histogenesis of this tumor remains controversial. A case of metaplastic mammary carcinoma with osteoclast-like giant cells in a 72-year-old woman is reported with p53 mutational analysis. Microscopically, the tumor was composed of a dominant sarcomatous stromal component containing osteoclast-like giant cells and a minor component of intraductal carcinoma. Immunostaining for p53 revealed strong positivity in both intraductal and sarcomatous components, but not in osteoclast-like giant cells. Mutational analysis of the p53 gene disclosed an identical point mutation in both intraductal and sarcomatous components, but not in osteoclast-like giant cells, indicating that both components share the same progenitor cells, and osteoclast-like giant cells represent a reactive infiltrate.

Analysis of protein expression and gene mutation of c-kit in colorectal neuroendocrine carcinomas

Primary neuroendocrine carcinomas of the colon are rare but highly aggressive malignancies. The recent observations that c-kit protooncogene, a tyrosine kinase, is overexpressed in a subset of small cell lung cancer and that selective kinase inhibitors block the in vitro growth of small cell lung cancer cell lines prompted us to investigate the expression and mutation status of the c-kit gene in colorectal neuroendocrine carcinomas. Sixty-six cases of primary colorectal neuroendocrine carcinoma were collected from 13 institutions, including 36 small cell carcinomas and 30 moderately differentiated neuroendocrine carcinomas. Immunohistochemical studies using a polyclonal antibody against c-kit protein (CD117) demonstrated a strong and diffuse cytoplasmic staining in 15 cases (23%), which were relatively equally distributed in the small cell and moderately differentiated subgroups. As controls, 25 conventional colorectal adenocarcinomas, 26 colorectal adenomas and 19 colorectal carcinoid tumors were all negative, whereas 15 gastrointestinal stromal tumors were all positive, for kit expression. In contrast to gastrointestinal stromal tumors, kit-overexpressing neuroendocrine carcinomas showed no mutations in the juxtamembrane domain (exon 11) of the c-kit gene as determined by mutational analysis. Kaplan-Meier analysis with the log-rank test revealed that the patients with kit-positive tumors did not differ significantly in survival from those with kit-negative tumors (P = 0.77). These results indicate that c-kit overexpression observed in a subset of colorectal neuroendocrine carcinomas may not be mediated via activating mutations, and does not appear to be an initiating event during tumorigenesis because of lack of c-kit expression in other types of colorectal epithelial neoplasms. More importantly, our observations may have potential therapeutic implications since specific tyrosine kinase inhibitors have shown promise in the management of patients with kit-expressing malignancies.

Salivary gland-like tumours of the breast: surgical and molecular pathology

Breast glands and salivary glands are tubulo-acinar exocrine glands that can manifest as tumours with similar morphological features, but that differ in incidence and clinical behaviour depending on whether they are primary in breast or salivary glands. Salivary gland-like tumours of the breast are of two types: tumours with myoepithelial differentiation and those devoid of myoepithelial differentiation. The first and more numerous group comprises a spectrum of lesions ranging from "bona fide" benign (such as benign myoepithelioma and pleomorphic adenoma), to low grade malignant (such as adenoid cystic carcinoma, low grade adenosquamous carcinoma, and adenomyoepithelioma), to high grade malignant lesions (malignant myoepithelioma). The second group comprises lesions that have only recently been recognised, such as acinic cell carcinoma, oncocytic carcinoma of the breast, and the rare mucoepidermoid carcinoma.

Distribution of p63, a novel myoepithelial marker, in fine-needle aspiration biopsies of the breast: an analysis of 82 samples

BACKGROUND

The presence of myoepithelial cells (MECs) in fine-needle aspiration biopsies (FNAB) of the breast constitute an important criterion used to diagnose benign breast lesions. However, MECs sometimes have a distorted cytomorphology, and most of the previously evaluated myoepithelial markers do not have satisfactory sensitivity and specificity. p63, a recently characterized p53 homolog, is a nuclear transcription factor that is expressed in basal cells of multilayered epithelia and myoepithelial cells of the breast. The authors analyzed the immunocytochemical distribution of p63 in a series of 82 breast FNABs (30 benign lesions and 52 malignant breast lesions).

METHODS

Eighty-two archival, Papanicolaou-stained smears of breast lesions were retrieved from the files of the authors' institutions. Immunocytochemistry was performed according to the streptavidin-biotin-peroxidase complex technique using the antibody 4A4 (against all p63 isoforms). Two pathologists evaluated the distribution of p63 positive cells. Only nuclear reactivity was considered specific.

RESULTS

In benign lesions, p63 decorated the nuclei of MECs in all samples. p63 also stained naked nuclei in fibroadenomas. In malignant lesions, p63 was positive in MECs overlying malignant cell clusters in all 8 samples of ductal carcinoma in situ (DCIS), in 9 of 16 samples of pure invasive carcinomas (IC), and in 16 of 20 samples that contained both DCIS and IC. In 18 samples (36%), a variable population of p63 positive, malignant cells was observed. p63 failed to decorate stromal, neural, adipocytic, and smooth muscle cells in all samples.

CONCLUSIONS

p63 is a reliable nuclear marker of MECs in breast aspirates. Regardless of the fact that variable proportions of p63 positive, malignant cells were observed in 36% of breast carcinoma aspirates, p63 may be a useful adjunct antibody to confirm the presence of MECs in FNABs of benign breast lesions.

p63 expression in normal, hyperplastic and malignant breast tissues

BACKGROUND

p63 is a homologue of the p53 tumor suppressor gene and its protein is selectively expressed in the basal cells of a variety of epithelial tissues. It has recently been confirmed that p63 is expressed in the basal cells of normal prostate glands but not in prostatic carcinomas. Whether expression of p63 in breast correlates with tumor progression is the focus of this study.

METHODS

Forty cases, which all contained normal breast tissue, ductal hyperplasia, ductal carcinoma in situ and invasive ductal carcinoma in the same patient were included in this investigation using an indirect immunohistochemical method and double staining.

RESULTS

p63 was exclusively expressed in the myoepithelial cells of normal breast, partially expressed in ductal hyperplasia, rarely expressed in carcinoma in situ and not expressed in invasive carcinomas.

CONCLUSION

The results suggest an association between loss of p63 expression and progression of breast ductal carcinoma. p63 immunostaining might be of assistance for distinguishing invasive ductal carcinoma from ductal carcinoma in situ or rare questionable ductal hyperplastic lesions, leading to correct therapy clinically.

Novel and classic myoepithelial/stem cell markers in metaplastic carcinomas of the breast

Metaplastic carcinomas of the breast (MCBs) are unusual neoplasms characterized by an admixture of glandular epithelial components, which frequently exhibit features of squamous differentiation, and mesenchymal malignant components. Regardless of the presence of myoepithelial features in MCB, no consensus concerning their putative histogenesis has yet been achieved. Recently, novel putative myoepithelial markers have been developed, including p63, maspin, and P-cadherin. We assessed the expression of these myoepithelial markers in MCBs and compared their expression with classic myoepithelial markers. Immunohistochemistry using the streptavidin-biotin-peroxidase complex technique with antibodies raised against p63, maspin, P-cadherin, actin (clones CGA7, 1A4 and HHF35), cytokeratin 14 (Ck14), and vimentin was performed on 16 MCBs (7 matrix-producing MCBs, 6 adenosquamous MCBs, and 3 MCBs with heterologous elements). In healthy breast lobules and ducts adjacent to the tumors, myoepithelial cells showed distinctive and consistent immunoreactivity for p63, maspin, P-cadherin, actin, S-100 protein, and Ck14. Matrix-producing MCBs were positive for maspin in all cases, for p63 in 4 of 7 cases, and for P-cadherin in 4 of 7 cases. Adenosquamous MCB showed immunoreactivity for p63, maspin, and P-cadherin in 5 of 6 cases. All novel myoepithelial markers and Ck14 decorated squamous cell islands. MCBs with heterologous elements were positive for p63 in 1 case, for maspin in all 3 cases, and for P-cadherin in 2 cases. All cases showed at least one of the novel myoepithelial markers. Eleven of 16 cases were positive for actin. Eleven of 14 cases reacted with Ck14, and all cases that stained for S-100 protein (9 of 9) and vimentin (13 of 13) were also positive. Based on our findings, the balance of probabilities favors that MCBs may have a basal or myoepithelial cell histogenesis and differentiation.

Epithelial to mesenchymal transition in human breast cancer can provide a nonmalignant stroma

A breast carcinoma biopsy showed cytochemical evidence of epithelial mesenchymal transition and an alpha-smooth muscle actin-positive stromal reaction. To study the lineage, and the nature of the cells in the stromal reaction, we derived a novel cell line, HBFL-1, from the explanted biopsy. HBFL-1 cells are immortal and exhibit a shared non-random X-chromosome inactivation pattern with the epithelial tumor of origin. Yet they closely resemble normal, finite-life-span fibroblasts by morphology, lack of tumor formation in nude mice, marker expression profile, protein pattern using two-dimensional gel electrophoresis and the ability to undergo myofibroblast conversion. HBFL-1 interacts reciprocally with tumor cells in collagen gel to induce activation of MMP2, leading to tumor-like behavior of epithelial colonies. In vivo, HBFL-1 cells resembled normal-derived myofibroblasts and conferred a significant 3.5- to 7-fold increase in MCF-7 tumor size in nude mice. However, that they were indeed not normal fibroblasts was revealed by residual keratin expression and formation of epithelial microfoci in a reconstituted basement membrane and in nude mice. We conclude that breast cancer can generate its own nonmalignant stroma and that one function for this is that of a reciprocal interaction with epithelial tumor cells to facilitate tumor growth.

A case of carcinoma of the breast with metaplasia to chondrosarcoma: Light microscopic and immunohistochemical features

The breast carcinomas with metaplasia are rare neoplasms showing both carcinomatous and sarcomatous elements. We described clinical behavior radiology findings and pathological features in case of breast carcinoma with heterologous chondrosarcomatoid metaplasia. The light microscopic features and the immunohistochemical markers of metaplastic carcinomas were highlighted in this paper with discussion focusing on histogenesis of this type of tumor.

Aneusomy 17 in breast cancer: its role in HER-2/neu protein expression and implication for clinical assessment of HER-2/neu status

HER-2/neu protein overexpression in breast cancer is mostly caused by HER-2/neu gene amplification. However, it is unclear whether aneusomy 17 may also play a role. Using immunohistochemistry assay (IHC) with DAKO antibody and manual quantitation, 189 specimens were selected from archival invasive breast cancer specimens, including most IHC-positive and some IHC-negative cases (n = 158 and 31, respectively). They were then analyzed by PathVysion fluorescence in situ hybridization (FISH) assay (Vysis, Inc., Downers Grove, IL) and by an image analyzer (ACIS; ChromaVision Medical Systems, Inc., San Juan Capistrano, CA)-assisted IHC quantitation. Ninety-two cases contained disomy 17 (chromosome 17 centromere, 1.76-2.25 signals per cell) whereas 97 cases had aneusomy 17, including 82 with low polysomy (2.26-3.75 signals per cell), 10 with high polysomy (> or =3.76 signals per cell), and 5 with hypodisomy (> or =1.75 signals per cell). HER-2/neu protein expression had the highest correlation with HER-2/neu gene dosage (copy number; r =.826), followed by the HER-2/neu gene to chromosome 17 ratio (r =.733). The lowest correlation was with the chromosome 17 copy number (r =.307), on which the 10 cases with high polysomy 17 had a disproportionately high impact. The FISH assay using the PathVysion criterion for HER-2/neu gene amplification (HER-2/neu gene to chromosome 17 ratio, > or = 2.00) achieved higher concordance with ACIS IHC than did an alternative FISH criterion (absolute HER-2/neu gene copy number, > or = 4.00 signals per cell). Most ACIS IHC-PathVysion FISH-discordant cases contained disomy or low polysomy 17, whereas all 10 cases with high polysomy 17 had no such discordance. However, two cases with monosomy 17 had ACIS IHC-PathVysion FISH discordance, i.e., with gene amplification, but no protein overexpression. Both cases would have had no gene amplification if the alternative FISH criterion had been used. In conclusion, aneusomy 17 is common in breast cancer. Except in a certain subset of cases, aneusomy 17 probably is not a significant factor for HER-2/neu protein expression or for clinical assessment of HER-2/neu status.