Marcia Edelweiss

Genomic landscape of adenoid cystic carcinoma of the breast.

Adenoid cystic carcinoma (AdCC) is a rare type of triple‐negative breast cancer (TNBC) characterized by the presence of the MYB–NFIB fusion gene. The molecular underpinning of breast AdCCs other than the MYB–NFIB fusion gene remains largely unexplored. Here we sought to define the repertoire of somatic genetic alterations of breast AdCCs. We performed whole‐exome sequencing, followed by orthogonal validation, of 12 breast AdCCs to determine the landscape of somatic mutations and gene copy number alterations. Fluorescence in situ hybridization and reverse‐transcription PCR were used to define the presence of MYB gene rearrangements and MYB–NFIB chimeric transcripts. Unlike common forms of TNBC, we found that AdCCs have a low mutation rate (0.27 non‐silent mutations/Mb), lack mutations in TP53 and PIK3CA and display a heterogeneous constellation of known cancer genes affected by somatic mutations, including MYB, BRAF, FBXW7, SMARCA5, SF3B1 and FGFR2. MYB and TLN2 were affected by somatic mutations in two cases each. Akin to salivary gland AdCCs, breast AdCCs were found to harbour mutations targeting chromatin remodelling, cell adhesion, RNA biology, ubiquitination and canonical signalling pathway genes. We observed that, although breast AdCCs had rather simple genomes, they likely display intra‐tumour genetic heterogeneity at diagnosis. Taken together, these findings demonstrate that the mutational burden and mutational repertoire of breast AdCCs are more similar to those of salivary gland AdCCs than to those of other types of TNBCs, emphasizing the importance of histological subtyping of TNBCs. Furthermore, our data provide direct evidence that AdCCs harbour a distinctive mutational landscape and genomic structure, irrespective of the disease site of origin. Copyright

Massively parallel sequencing of phyllodes tumours of the breast reveals actionable mutations, and TERT promoter hotspot mutations and TERT gene amplification as likely drivers of progression

Phyllodes tumours (PTs) are breast fibroepithelial lesions that are graded based on histological criteria as benign, borderline or malignant. PTs may recur locally. Borderline PTs and malignant PTs may metastasize to distant sites. Breast fibroepithelial lesions, including PTs and fibroadenomas, are characterized by recurrent MED12 exon 2 somatic mutations. We sought to define the repertoire of somatic genetic alterations in PTs and whether these may assist in the differential diagnosis of these lesions. We collected 100 fibroadenomas, 40 benign PTs, 14 borderline PTs and 22 malignant PTs; six, six and 13 benign, borderline and malignant PTs, respectively, and their matched normal tissue, were subjected to targeted massively parallel sequencing (MPS) using the MSK‐IMPACT sequencing assay. Recurrent MED12 mutations were found in 56% of PTs; in addition, mutations affecting cancer genes (eg TP53, RB1, SETD2 and EGFR) were exclusively detected in borderline and malignant PTs. We found a novel recurrent clonal hotspot mutation in the TERT promoter (−124 C>T) in 52% and TERT gene amplification in 4% of PTs. Laser capture microdissection revealed that these mutations were restricted to the mesenchymal component of PTs. Sequencing analysis of the entire cohort revealed that the frequency of TERT alterations increased from benign (18%) to borderline (57%) and to malignant PTs (68%; p < 0.01), and TERT alterations were associated with increased levels of TERT mRNA (p < 0.001). No TERT alterations were observed in fibroadenomas. An analysis of TERT promoter sequencing and gene amplification distinguished PTs from fibroadenomas with a sensitivity and a positive predictive value of 100% (CI 95.38–100%) and 100% (CI 85.86–100%), respectively, and a sensitivity and a negative predictive value of 39% (CI 28.65–51.36%) and 68% (CI 60.21–75.78%), respectively. Our results suggest that TERT alterations may drive the progression of PTs, and may assist in the differential diagnosis between PTs and fibroadenomas. Copyright

The repertoire of somatic genetic alterations of acinic cell carcinomas of the breast: an exploratory, hypothesis-generating study.

Acinic cell carcinoma (ACC) of the breast is a rare form of triple‐negative (that is, oestrogen receptor‐negative, progesterone receptor‐negative, HER2‐negative) salivary gland‐type tumour displaying serous acinar differentiation. Despite its triple‐negative phenotype, breast ACCs are reported to have an indolent clinical behaviour. Here, we sought to define whether ACCs have a mutational repertoire distinct from that of other triple‐negative breast cancers (TNBCs). DNA was extracted from microdissected formalin‐fixed, paraffin‐embedded sections of tumour and normal tissue from two pure and six mixed breast ACCs. Each tumour component of the mixed cases was microdissected separately. Tumour and normal samples were subjected to targeted capture massively parallel sequencing targeting all exons of 254 genes, including genes most frequently mutated in breast cancer and related to DNA repair. Selected somatic mutations were validated by targeted amplicon resequencing and Sanger sequencing. Akin to other forms of TNBC, the most frequently mutated gene found in breast ACCs was TP53 (one pure and six mixed cases). Additional somatic mutations affecting breast cancer‐related genes found in ACCs included PIK3CA, MTOR, CTNNB1, BRCA1, ERBB4, ERBB3, INPP4B, and FGFR2. Copy number alteration analysis revealed complex patterns of gains and losses similar to those of common forms of TNBCs. Of the mixed cases analysed, identical somatic mutations were found in the acinic and the high‐grade non‐acinic components in two out of four cases analysed, providing evidence of their clonal relatedness. In conclusion, breast ACCs display the hallmark somatic genetic alterations found in high‐grade forms of TNBC, including complex patterns of gene copy number alterations and recurrent TP53 mutations. Furthermore, we provide circumstantial genetic evidence to suggest that ACCs may constitute the substrate for the development of more aggressive forms of triple‐negative disease. Copyright

Are acinic cell carcinomas of the breast and salivary glands distinct diseases

Acinic cell carcinomas (AcCC) of the breast have been reported to constitute the breast counterpart of salivary gland AcCCs, based on the similarities of their histological and immunohistochemical features. Breast AcCC is a vanishingly rare form of triple‐negative breast cancer (TNBC). Recent studies have demonstrated that in TNBCs, the two driver genes most frequently mutated are TP53 (82%) and PIK3CA (10%). We sought to define whether breast AcCCs would harbour TP53 and PIK3CA somatic mutations, and if so, whether these would be present in salivary gland AcCCs.

Infiltrating epitheliosis of the breast: characterization of histological features, immunophenotype and genomic profile

Infiltrating epitheliosis is a rare complex sclerosing lesion (CSL) of the breast, characterized by infiltrating ducts immersed in a scleroelastotic stroma and filled with cells having architectural and cytological patterns reminiscent of those of usual ductal hyperplasia. In this study we sought to define the molecular characteristics of infiltrating epitheliosis.

Low interobserver agreement in cytology grading of mucinous pancreatic neoplasms

Identifying high‐grade features in patients with pancreatic mucinous neoplasms (MNs) is important for patient management. The reproducibility of MN cytology grading has been evaluated to a limited extent. In the current study, the authors evaluated interobserver variability in grading MNs and the identification of neoplastic mucin in endoscopic ultrasound‐guided fine‐needle aspiration specimens.

Challenges in the interpretation of breast core biopsies.

Abstract:  The aim of core needle biopsy (CNB) is to diagnose a breast abnormality prior to open surgical excision. The radiology–pathology correlation helps in interpretation of pathologic findings and is greatly assisted by specimen radiology of all cores performed for calcifications, separation of cores containing calcification from those without, and the availability of the specimen radiograph to the pathologist at the time of reporting. The nature of the imaging abnormality should also be clearly conveyed. CNB is processed in a routine manner for paraffin embedding with preservation of sufficient material in the block for further studies as needed. Possible pitfalls include the loss of calcifications at the time of section cutting, calcium remained in the formalin of the specimen container, and failure to recognize calcium oxalate deposition in the CNB. The challenges of CNB interpretation are complicated by the availability of only limited material, but are generally similar to those encountered in open surgical excision specimens. This discussion focuses on high‐risk lesions and lesions that raise management issues. The most prudent approach for the pathologist is to provide sufficient information to prompt a surgical excision without overdiagnosing the lesion, thus placing the patient into the appropriate therapeutic algorithm.

Atherosclerosis and acute arterial thrombosis in rabbits : a model using balloon desendothelization without dietary intervention

Acute thrombosis can be induced in rabbits by a triggering protocol using Russells viper venom and histamine given after 8 months of a 1% cholesterol diet and balloon desendothelization. In the present study, we tested the hypothesis that aortic desendothelization performed 4 months before the triggering protocol without a high cholesterol diet is a highly effective and less expensive way of producing arterial atherosclerosis and thrombosis. Nineteen male New Zealand white rabbits on a normal diet were studied. The control group (N = 9) received no intervention during the 4-month observation period, while the other group (N = 10) was submitted to aortic balloon desendothelization using a 4F Fogarty catheter. At the end of this period, all animals were killed 48 h after receiving the first dose of the triggering treatment. Eight of 10 rabbits (80%) in the balloon-trauma group presented platelet-rich arterial thrombosis while none of the animals in the control group had thrombus formation (P < 0.01). Thus, this model, using balloon desendothelization without dietary manipulation, induces arterial atherosclerosis and thrombosis and may provide possibilities to test new therapeutic approaches.

Accuracy of telomerase in estimating breast cancer risk: A systematic review and meta-analysis

OBJECTIVE To determine the accuracy of telomerase activity in predicting a higher risk for breast cancer. STUDY DESIGN A quantitative systematic review was performed. Studies that detected telomerase activities in breast tissue were included. RESULTS Twenty-five primary studies were analyzed, which included 2395 breast lesions. The proportion of breast cancer was 60.8%. Eighty-two percent (1193/1455) of breast cancer cases and 18% (169/940) of benign lesions cases were positive for telomerase activity. For breast cancer vs benign or normal breast tissue, the pooled likelihood ratio for the presence of telomerase activity was 4.5 (95% confidence interval [CI], 3.1-6.5) and the post-test probability was 88% (95% CI, 83-91). For breast cancer vs benign or normal tissue, the area under the summary receiver operating characteristic (SROC) curve was 0.89 with the Q* point value of 0.82. CONCLUSION Our systematic review showed that telomerase activity was significantly present in breast cancer when compared with normal breast tissue or benign breast lesions.

Bi-allelic alterations in DNA repair genes underpin homologous recombination DNA repair defects in breast cancer

Homologous recombination (HR) DNA repair‐deficient (HRD) breast cancers have been shown to be sensitive to DNA repair targeted therapies. Burgeoning evidence suggests that sporadic breast cancers, lacking germline BRCA1/BRCA2 mutations, may also be HRD. We developed a functional ex vivo RAD51‐based test to identify HRD primary breast cancers. An integrated approach examining methylation, gene expression, and whole‐exome sequencing was employed to ascertain the aetiology of HRD. Functional HRD breast cancers displayed genomic features of lack of competent HR, including large‐scale state transitions and specific mutational signatures. Somatic and/or germline genetic alterations resulting in bi‐allelic loss‐of‐function of HR genes underpinned functional HRD in 89% of cases, and were observed in only one of the 15 HR‐proficient samples tested. These findings indicate the importance of a comprehensive genetic assessment of bi‐allelic alterations in the HR pathway to deliver a precision medicine‐based approach to select patients for therapies targeting tumour‐specific DNA repair defects. Copyright