p16 and pRb immunohistochemical expression increases with increasing tumour grade in mammary phyllodes tumours

Aims: Control of cell cycling and proliferation is critical to the development of neoplasia and may play a role in the pathogenesis of phyllodes tumours (PTs). This study aimed to evaluate the immunohistochemical expression of certain proteins from the G1 ⁄ S transition of the cell cycle in a cohort of PTs, to determine their role in tumour pathogenesis and to identify any associations with patient outcome. Methods and results: Sixty-five PTs (34 benign, 23 borderline and eight malignant) diagnosed at a single institution between 1990 and 2006 were analysed. Immunohistochemistry for p16, pRb, cyclin D1 and Ki67 was performed. Expression of the following markers increased significantly with tumour grade: stromal nuclear and cytoplasmic p16 (P = 0.01 and 0.002, respectively), stromal and epithelial pRb (P = 0.000 000 06 and 0.004, respectively), and stromal and epithelial Ki67 (P = 0.03 and 0.04, respectively). Epithelial pRb scores of 7 (range 0–7) were significantly associated with reduced disease-free survival (DFS) compared with scores of <7 (P = 0.0009). No relationship was found between cyclin D1 expression in either the epithelium or the stroma, and grade or DFS. Conclusions: The results suggest that alterations at the G1 ⁄ S transition of the cell cycle play an important role in the progression of PTs

Molecular alterations in metaplastic breast carcinoma

Metaplastic carcinoma of the breast is a rare and heterogeneous subtype of breast carcinoma with a generally poor outcome, and few therapeutic options once disease recurs or progresses. Metaplastic carcinomas of the breast are usually of a larger size at diagnosis, with less frequent nodal metastasis compared with invasive ductal carcinoma no special type, and lack hormone and HER2 receptor expression. Recent research has revealed some potentially actionable genetic changes in a subset of these rare tumours. However, ongoing efforts to further characterise the genetic basis and the molecular alterations underlying the distinctive morphological and clinical characteristics of these tumours are needed in order to identify new targets for treatment. This review will describe the theories of pathogenesis of metaplastic breast carcinoma, and highlight genetic changes and potential therapeutic targets in this generally poor prognosis malignancy

Pathogenic mechanisms in the initiation and progression of mammary phyllodes tumours

Mammary phyllodes tumours (PTs) are rare fibroepithelial neoplasms of the breast. They have a propensity to recur locally and the ability to metastasise. There is some correlation between the histological parameters of PTs and their biological behaviour; however, no single feature or grading scheme can accurately predict the behaviour of a PT. The PTs that will recur and/or metastasise are not being precisely delineated with the currently available diagnostic tools. A number of pathways/markers have been implicated in the pathogenesis of PTs including hormone receptors, members of the Wnt pathway, cell cycle proteins, factors involved in angiogenesis, tyrosine kinase receptors and matrix metalloproteases. The currently available evidence supports a model where initiation of PTs involves interactions between the epithelium and stroma and these interactions are lost with the progression to malignancy such that growth of the stroma becomes autonomous of the epithelium. Loss of the stromal-epithelial interdependancy, increased stromal proliferation, angiogenesis and matrix alterations appear to be involved in the progression to malignancy

Phyllodes tumours of the breast : a clinicopathological analysis of 65 cases from a single institution

The aim of this study was to document the clinical and pathological features of a large single institutional series of ethnically diverse patients with phyllodes tumours (PTs), and to determine which characteristics were predictive of outcome. Sixty five PTs were analysed; 34 were benign, 23 borderline and eight malignant (34 low grade and 31 high grade PTs on a two tiered grading system). Nine patients (15%) had local recurrences. A greater percentage of higher grade tumours recurred and women of Asian origin had a higher recurrence rate compared to the non-Asian patients. The 5 year disease-free survival was 81% and time to recurrence was significantly lower in the high grade group. No metastases or deaths from disease were recorded. The mean age at diagnosis significantly increased with tumour grade. The mean tumour volume also significantly increased with grade. Tumour grade was the only parameter related significantly to outcome

Proteins from the Wnt pathway are involved in the pathogenesis and progression of mammary phyllodes tumours

The Wnt pathway is important in cell signalling transduction and is involved in the pathogenesis of multiple tumour types. A comprehensive analysis of the expression of Wnt signalling pathway proteins in mammary phyllodes tumours (PTs) has not been previously performed. This study aims to evaluate the immunohistochemical expression of Wnt pathway proteins in a cohort of PTs, to determine their role in tumour pathogenesis and to identify any associations with patient outcome. 65 PTs (34 benign, 23 borderline and 8 malignant) diagnosed at a single institution between 1990 and 2006 were analysed. Immunohistochemical stains were performed on tissue microarrays for b-catenin, Wnt1, Wnt5a, SFRP4 and E-cadherin. Stroma and epithelium were scored separately. Stromal cytoplasmic Wnt5a and SFRP4 expression showed significant progressive increases in expression with increasing grade (p=0.002 and p=0.02 respectively). Epithelial membranous and stromal nuclear b-catenin, epithelial cytoplasmic Wnt1 and epithelial E-cadherin all also showed increasing expression with increasing tumour grade, however, the differences were not significant. Disease-free survival was significantly decreased (p=0.0017) with positive epithelial Ecadherin staining. Results suggest that alterations in the Wnt pathway are important in the progression and in the epithelial and stromal interactions in PTs. They have important implications for understanding the pathogenesis of these uncommon but clinically important tumours

E-caherin expression in the epithelial components of mammary phyllodes tumors

Phyllodes tumors are rare but clinically important fibroepithelial tumors of the breast. Both epithelial and stromal components actively interact with each other to participate in phyllodes tumor development. Accumulated evidence suggests that the Wnt signaling pathway is important in this stromal-epithelial interaction. Given that Wnt signaling also affects E-cadherin–dependent cellular adhesion and alteration of E-cadherin is common in epithelial cancers, it is possible that alteration of E-cadherin occurs also in the epithelial components of phyllodes tumor. We assessed epithelial E-cadherin expression in 155 phyllodes tumor cases, including 92 benign (59%), 42 borderline (27%), and 21 malignant phyllodes tumor (14%), by immunohistochemistry. Its expression was correlated with clinicopathologic features and phyllodes tumor recurrence. Significant correlations of both membranous and cytoplasmic E-cadherin expression were found with stromal cellularity (P = .009 and .013, respectively), overgrowth (P = .005 and .009, respectively), and mitotic counts (P = .023 and .029, respectively) but not tumor grade, margin, and nuclear atypia. Interestingly, a significantly higher level of cytoplasmic epithelial E-cadherin expression was found in those tumors with recurrence (score, 278.79 ± 40.91 versus 250.00 ± 63.46) and shorter specific disease-free survival (172.24 ± 12.63 versus 207.24 ± 19.71 months). Further multivariate analysis showed epithelial E-cadherin expression as an independent prognostic factor for phyllodes tumor–specific survival (P < .001 for cytoplasmic staining and .001 for membranous staining). In conclusion, we have demonstrated an association of epithelial E-cadherin expression with stromal histologic features and disease recurrence in phyllodes tumor. These findings provide further evidence of the importance of stromal-epithelial interactions in phyllodes tumors and highlight the potential value of epithelial components in prognostication

Involvement of α- and ß-catenins and E-cadherin in the development of mammary phyllodes tumours

Aims: Phyllodes tumours (PT) are rare but clinically important fibroepithelial tumours of the breast. beta-Catenin, a key component in Wnt signalling, has been shown to be important in the development of PT. It also functions as a component of the cadherin complex, which may therefore be implicated in PT pathogenesis. By assessing stromal alpha-catenin, beta-catenin and E-cadherin expression in 158 PT cases using immunohistochemistry and examining associations with clinicopathological features, we aimed to determine the role of these proteins in PT pathogenesis. Methods and results: Cytoplasmic beta-catenin correlated with alpha-catenin expression. A significantly higher expression of both markers was observed in borderline than in benign PT (P = 0.003 and <0.001, respectively), but a lower level was found in malignant PT. Cytoplasmic E-cadherin expression was significantly higher in borderline and malignant than in benign PT (P = 0.001 and 0.012, respectively), but was not correlated with other markers. Both E-cadherin and alpha-catenin showed stronger correlations with histological parameters than beta-catenin. alpha-Catenin showed a significant correlation with recurrence (P = 0.005 and 0.016, respectively). Conclusions: alpha- and beta-catenins may be important in the early stages of PT development, while E-cadherin may be required for malignant development. The correlation of alpha-catenin expression with tumour recurrence may be relevant in predicting PT behaviour

Recent insights into the molecular pathogenesis of mammary phyllodes tumours

Phyllodes tumours (PTs) of the breast are true biphasic neoplasms within which interactions between the epithelium and stroma are critical for tumour development and progression. Despite numerous studies reporting the results of ancillary marker investigations in PTs, the current histological grading systems remain unreliable at predicting clinical outcome even when supplemented by these markers. As a consequence, there has been much interest in the prospect of using molecular/genetic techniques to develop a more robust "grading" system. This review focuses on recent cytogenetic and molecular studies investigating the pathogenesis of PTs and those correlating molecular findings with clinicopathological features of the tumours. Recent data highlight that intratumoural genetic heterogeneity is common in PTs and may account for the reported lack of correlation between histological grading and clinical behaviour. The entire spectrum of molecular aberrations in PTs are yet to be fully defined, however recent array-based studies using comparative genomic hybridisation have reported that copy number changes increase with the progression from benign PT to malignancy. Tumour recurrence and progression is likely to reflect the presence of under-recognised subclones. p 16INK4a (CDKN2A) inactivation also appears to be important in PT pathogenesis. Further additional studies will be required to identify and validate new prognostic markers and therapeutic targets in order to improve the diagnosis, classification, prediction of outcome and management of patients with this rare neoplasm. Data generated from modern sequencing technologies are likely to provide new insights into the disease and assist in this endeavour

Increased epidermal growth factor receptor (EGFR) expression in malignant mammary phyllodes tumors

Mammary phyllodes tumors are uncommon stromal-epithelial neoplasms, and are divided into benign, borderline malignant and frankly malignant groups on the basis of their histological features. Accumulating evidence shows that epidermal growth factor receptor (EGFR) is involved in the pathogenesis and progression of many malignancies. This study investigated 453 phyllodes tumors (296 benign, 98 borderline, 59 malignant) for EGFR expression using immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for gene amplification. The staining was correlated to tumor margin status, degree of malignancy, stromal cellularity, mitotic activity, nuclear pleomorphism and stromal overgrowth. Cases with strong positive IHC staining were selected for FISH. The overall positive rate for EGFR was 16.2% (48/ 296), 30.6% (30/98) and 56% (33/59) for benign, borderline malignant and frankly malignant phyllodes tumors, respectively. FISH demonstrated egfr gene amplification in 8% of immunohistochemically positive cases. The results of this study provide strong evidence that EGFR overexpression is involved in the pathogenesis of phyllodes tumors, although gene amplification may not be the major underlying mechanism for overexpression

FISH analysis of selected soft tissue tumors : diagnostic experience in a tertiary center

Aim: Fluorescence in situ hybridization (FISH) is an important ancillary tool for the classification of bone/soft tissue (BST) tumors. The aim of this study was to evaluate the contribution of FISH to the final classification of common BST entities in the molecular pathology department of the Royal Prince Alfred Hospital (RPAH), which is one of the most important referral centers for the management of sarcomas in Australia. Methods: All routine diagnostic FISH tests performed on BST formalin-fixed paraffin embedded (FFPE) tissue specimens at the RPAH in a 5-year period (February, 2010-November, 2015) were reviewed. FISH analyses presented in this study include commercial break-apart probes (SS18, FUS, DDIT3, FUS, USP6, PDGFB, TFE3 and ALK) and a single enumeration (MDM2) probe. Results: There were 434 interpretable FISH assays on BST samples including MDM2 (n=180), SS18 (n=97), FUS (n=64), DDIT3 (n=37), USP6 (n=30), PDGFB (n=13), TFE3 (n=8) and ALK (n=5). Discrepancies between the histopathological diagnosis and the FISH results were seen in 12% of the cases. In this subset of discordant cases, FISH contributed to the re-classification of 7% of cases originally diagnosed as synovial sarcoma (SS18) and 6% of adipocytic neoplasms (MDM2) based on the presence or absence of the expected gene alteration. Conclusion: Our study confirms that paraffin FISH is a sensitive and specific ancillary tool in the diagnosis of BST neoplasms when used in the appropriate clinicopathological context. These findings highlight the need for further ancillary molecular tools in the diagnosis and characterization of challenging cases