Targeting LIF-mediated paracrine interaction for pancreatic cancer therapy and monitoring.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis largely owing to inefficient diagnosis and tenacious drug resistance. Activation of pancreatic stellate cells (PSCs) and consequent development of dense stroma are prominent features accounting for this aggressive biology1,2. The reciprocal interplay between PSCs and pancreatic cancer cells (PCCs) not only enhances tumour progression and metastasis but also sustains their own activation, facilitating a vicious cycle to exacerbate tumorigenesis and drug resistance3-7. Furthermore, PSC activation occurs very early during PDAC tumorigenesis8-10, and activated PSCs comprise a substantial fraction of the tumour mass, providing a rich source of readily detectable factors. Therefore, we hypothesized that the communication between PSCs and PCCs could be an exploitable target to develop effective strategies for PDAC therapy and diagnosis. Here, starting with a systematic proteomic investigation of secreted disease mediators and underlying molecular mechanisms, we reveal that leukaemia inhibitory factor (LIF) is a key paracrine factor from activated PSCs acting on cancer cells. Both pharmacologic LIF blockade and genetic Lifr deletion markedly slow tumour progression and augment the efficacy of chemotherapy to prolong survival of PDAC mouse models, mainly by modulating cancer cell differentiation and epithelial-mesenchymal transition status. Moreover, in both mouse models and human PDAC, aberrant production of LIF in the pancreas is restricted to pathological conditions and correlates with PDAC pathogenesis, and changes in the levels of circulating LIF correlate well with tumour response to therapy. Collectively, these findings reveal a function of LIF in PDAC tumorigenesis, and suggest its translational potential as an attractive therapeutic target and circulating marker. Our studies underscore how a better understanding of cell-cell communication within the tumour microenvironment can suggest novel strategies for cancer therapy.

Advances in uterine inflammatory myofibroblastic tumours: Diagnostic challenges and risk stratification.

The current understanding of inflammatory myofibroblastic tumours (IMTs) of the gynaecological tract has recently been enhanced by their increased recognition. This increase is largely due to greater accessibility to RNA-based molecular assays used to identify their defining ALK rearrangements. This review summarises the clinical characteristics, morphological spectrum, immunohistochemical profile and molecular underpinnings of uterine IMT. Additionally, this review discusses practical diagnostic considerations including overlap between uterine IMT and smooth muscle tumours as well as pregnancy-associated uterine IMT. Finally, we highlight recent literature demonstrating the potential for aggressive behaviour in uterine IMT, including a novel risk stratification model for identifying high-risk IMT.

Integrated Genomic and Clinicopathologic Approach Distinguishes Pancreatic Grade 3 Neuroendocrine Tumor From Neuroendocrine Carcinoma and Identifies a Subset With Molecular Overlap.

Distinguishing grade 3 pancreatic neuroendocrine tumor (G3 PanNET) from neuroendocrine carcinoma (PanNEC) is a known diagnostic challenge, and accurate classification is critical because clinical behavior and therapies differ. Although current recommendations suggest that immunohistochemistry for p53, Rb, ATRX, and DAXX can distinguish most cases, some cases remain difficult to classify using this approach. In this study, we reviewed 47 high-grade neoplasms originally diagnosed as pancreatic neuroendocrine neoplasms. In addition to the currently recommended stains, we performed capture-based sequencing of approximately 500 cancer genes and immunohistochemistry for p16 and trypsin or chymotrypsin. Using an integrated molecular and clinicopathologic approach, 42 (89%) of 47 cases had a clear final diagnosis of either G3 PanNET (n = 17), PanNEC (n = 17), or mixed acinar-NEC (n = 8). The 17 G3 PanNETs demonstrated frequent alterations in MEN1 (71%), DAXX (47%), ATRX (24%), TSC2 (35%), SETD2 (42%), and CDKN2A (41%). Contrary to prior reports, TP53 alterations were also common in G3 PanNETs (35%) but were always mutually exclusive with CDKN2A alterations in this group. The 17 PanNECs demonstrated frequent alterations in TP53 (88%), cell cycle genes RB1 (47%), CCNE1/CCND1 (12%), CDKN2A (29%), and in KRAS (53%) and SMAD4 (41%); TP53 was coaltered with a cell cycle gene in 76% of PanNECs. Diffuse strong p16 staining was observed in 69% of PanNECs in contrast to 0% of G3 PanNETs. The 8 acinar-NECs had recurrent alterations in ATM (25%), APC (25%), and STK11 (25%). Five cases remained difficult to classify, 3 of which exhibited overlapping molecular features with alterations in MEN1 with or without ATRX, and RB1 with or without TP53, making it unclear whether to classify as PanNET or PanNEC. Our data demonstrate that molecular profiling and immunohistochemistry for p16 greatly improve the diagnostic accuracy of high-grade pancreatic neuroendocrine neoplasms and identify a subset of rare cases with overlapping features of both PanNET and PanNEC.

Use of orcein as an adjunct stain in the evaluation of advanced liver fibrosis.

AIMS: Advanced liver fibrosis can regress following the elimination of causative injuries. Trichrome (TC) stain has traditionally been used to evaluate the degree of fibrosis in liver, although it is rarely helpful in assessing quality of fibrosis (i.e. progression and regression). Orcein (OR) stain highlights established elastic fibres, but its use in examining fibrosis is not well recognised. This study assessed the potential utility of comparing OR and TC staining patterns to evaluate the quality of fibrosis in various settings of advanced fibrosis. METHODS AND RESULTS: The haematoxylin and eosin and TC stains of 65 liver resection/explant specimens with advanced fibrosis caused by different elements were reviewed. Twenty-two cases were scored as progressive (P), 16 as indeterminate (I) and 27 as regressive (R) using TC stain based on the Beijing criteria. The OR stains confirmed 18 of 22 P cases. The remaining P cases showed either stable fibrosis or mixed P and R. Of the 27 R cases, 26 were supported by OR stain, with many showing thin perforated septa typically seen in adequately treated viral hepatitis cases. The 16 I cases showed a variety of OR staining patterns, which allowed for further subclassification than using TC stain alone. Viral hepatitis cases were enriched for regressive features (17 of 27). CONCLUSIONS: Our data demonstrated the utility of OR as an adjunctive stain to evaluate the changes in fibrosis in cases of cirrhosis.

An exploration in pitfalls in interpreting SDHB immunohistochemistry.

AIMS: Mutations and epimutations in genes encoding the succinate dehydrogenase complex (SDHx) are associated with multiple tumour types in which identification of SDH-deficiency has significant management implications. Immunohistochemistry (IHC) for the succinate dehydrogenase B (SDHB) subunit can help to detect SDH-deficiency, which manifests as complete loss of staining in tumour cells. However, a subset of SDH-deficient tumours can show aberrant cytoplasmic SDHB-IHC staining patterns and be misinterpreted as 'retained', a diagnostic pitfall complicating interpretation. Herein, we characterise in detail aberrant SDHB-IHC staining patterns in SDH-deficient tumours. METHODS AND RESULTS: We identified 23 tumours from patients with known germline SDHx and/or molecularly confirmed SDHx pathogenic/likely-pathogenic variants in their tumour. Of these, eight (35%) showed significant SDHB-IHC staining: one SDHA-, one SDHB-, three SDHC- and three SDHD-mutated cases. In all eight cases, closer inspection revealed differences in intensity and intracellular distribution of SDHB-IHC staining in tumour cells compared to adjacent non-neoplastic cells: non-neoplastic cells showed intense cytoplasmic coarse granular staining; tumour cells in seven of eight cases showed weak to focally strong, cytoplasmic blush to fine granular staining, in > 80% of cells. The remaining case in the initial block showed variably strong non-granular cytoplasmic staining with globular perinuclear accentuation throughout, only subtly distinct from the staining pattern of non-neoplastic cells. SDHB-IHC performed on two additional blocks in this latter case revealed significant intratumoral heterogeneity, including convincing areas of complete loss. CONCLUSIONS: When evaluating SDHB-IHC, care should be taken to distinguish true retained expression from aberrant cytoplasmic expression, which may be difficult to appreciate. Sometimes this may require additional molecular testing.

Hepatocellular adenomas in the Turkish population: reclassification according to updated World Health Organization criteria.

AIMS: Hepatocellular adenoma (HCA) is an uncommon liver neoplasm, and studies of HCA subtypes have been primarily limited to France, the USA, and Japan. The aim of this study was to describe the clinicopathological features of HCA subtypes in Turkey. METHODS AND RESULTS: The resection specimens of 59 cases diagnosed as 'hepatocellular adenoma' collected from 15 institutions were reviewed to confirm the diagnosis and to classify them according to the current World Health Organization 2019 classification. Immunostaining for glutamine synthetase, liver fatty acid-binding protein, C-reactive protein, ß-catenin and reticulin was performed. Of the 59 cases, 48 (81%) were diagnosed as HCA. We identified 24 (50%) hepatocyte nuclear factor 1α (HNF1α)-inactivated HCAs, five (10%) inflammatory HCAs, 15 (32%) ß-catenin-activated HCAs, three (6%) ß-catenin-activated inflammatory HCAs, and one (2%) unclassified HCA. HCA patients were predominantly female (female/male ratio of 5:1); they had a median age of 34 years and a median tumour diameter of 60 mm. In the ß-catenin-activated HCA group, nine cases (19%) showed cytoarchitectural atypia, and were also referred to as atypical hepatocellular neoplasms. In the ß-catenin-activated HCA group, three cases (6%) showed focal areas supportive of transition to HCA. The original diagnosis of HCA was changed to well-differentiated hepatocellular carcinoma in nine cases and to focal nodular hyperplasia in two cases. CONCLUSION: In our series, the major HCA subtype was HNF1α-inactivated HCA. We found a low incidence of inflammatory-type HCA. Our data also showed that ß-catenin-activated hepatocellular neoplasms, including cases with atypical histology, constituted a relatively high proportion of the cases. These findings are in contrast to those of most other studies of HCA subtypes.

Corded and Hyalinized Endometrioid Adenocarcinoma (CHEC) of the Uterine Corpus are Characterized by CTNNB1 Mutations and Can Show Adverse Clinical Outcomes.

Corded and hyalinized endometrioid adenocarcinoma (CHEC) is a morphologic variant of endometrioid adenocarcinoma that is typically low-grade [International Federation of Gynecology and Obstetrics (FIGO) grade 1-2]. CHEC exhibits a biphasic appearance with gland forming adenocarcinoma merging with a diffuse component with corded growth often in a hyalinized matrix; squamous differentiation is frequent and osteoid production can be seen. This morphologic appearance can invoke a large differential diagnosis including carcinosarcoma. CHEC is thought to be associated with good clinical outcome although the available data is sparse. We performed detailed clinical, morphologic, immunohistochemical, and molecular analyses on a cohort of 7 CHEC. Six cases exhibited features of classic low-grade CHEC while one case showed greater cytologic atypia (high-grade CHEC). Patient age ranged from 19 to 69 yr. Four patients presented at stage I, 2 at stage II, and 1 at stage III. All tumors demonstrated nuclear staining for beta-catenin and loss of E-cadherin in the corded and hyalinized component. There was relative loss of epithelial markers. Loss of PTEN and ARID1A was seen in 4 and 3 tumors, respectively, and 1 tumor displayed loss of MLH1 and PMS2. Next-generation sequencing revealed CTNNB1 and PI3K pathway mutations in all 7 cases with TP53 and RB1 alterations in the high-grade CHEC. Clinical follow-up was available for 6 patients; 2 died of disease (48 and 50 mo), 2 are alive with disease (both recurred at 13 mo), and 2 have no evidence of disease (13 and 77 mo). Our study shows that CHEC universally harbors CTNNB1 mutations with nuclear staining for beta-catenin, can rarely show high-grade cytology, and can be associated with adverse clinical outcomes.

Genomic profiling of combined hepatocellular-cholangiocarcinoma reveals similar genetics to hepatocellular carcinoma.

Combined hepatocellular-cholangiocarcinomas (CHC) are mixed tumours with both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC) components. CHC prognosis is similar to intrahepatic CC (ICC) and worse than HCC; staging and treatment generally follow ICC algorithms. However, the molecular biology of CHC remains poorly characterised. We performed capture-based next-generation sequencing of 20 CHC and, for comparison, 10 ICC arising in cirrhosis. Intratumour heterogeneity was assessed by separately sequencing the HCC and CC components of nine CHC. CHC demonstrated molecular profiles similar to HCC, even in the CC component. CHC harboured recurrent alterations in TERT (80%), TP53 (80%), cell cycle genes (40%; CCND1, CCNE1, CDKN2A), receptor tyrosine kinase/Ras/PI3-kinase pathway genes (55%; MET, ERBB2, KRAS, PTEN), chromatin regulators (20%; ARID1A, ARID2) and Wnt pathway genes (20%; CTNNB1, AXIN, APC). No CHC had alterations in IDH1, IDH2, FGFR2 or BAP1, genes typically mutated in ICC. TERT promoter mutations were consistently identified in both HCC and CC components, supporting TERT alteration as an early event in CHC evolution. TP53 mutations were present in both components in slightly over half the TP53-altered cases. By contrast, focal amplifications of CCND1, MET and ERRB2, as well as Wnt pathway alterations, were most often exclusive to one component, suggesting that these are late events in CHC evolution. ICC in cirrhosis demonstrated alterations similar to ICC in non-cirrhotic liver, including in IDH1 or IDH2 (30%), CDKN2A (40%), FGFR2 (20%), PBRM1 (20%), ARID1A (10%) and BAP1 (10%). TERT promoter and TP53 mutation were present in only one ICC each. Our data demonstrate that CHC genetics are distinct from ICC (even in cirrhosis) and similar to HCC, which has diagnostic utility and implications for treatment. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Fecal Microbiota Transplantation in Pouchitis: Clinical, Endoscopic, Histologic, and Microbiota Results from a Pilot Study.

AIMS: This pilot study assessed the efficacy, safety, and microbiome dynamics of fecal microbiota transplantation (FMT) for patients with chronic pouchitis. METHODS: A prospective open-label pilot study was performed at an academic center among pouchitis patients undergoing FMT. Patients received a minimum of a single FMT by pouchoscopy from healthy, screened donors. The primary outcome was clinical improvement in pouchitis assessed by patient survey at week 4. Secondary outcomes included decrease in total Pouchitis Disease Activity Index (PDAI) Score ≥ 3 at week 4, bowel movement frequency, ESR, CRP, fecal calprotectin, abdominal pain, and PDAI subscores including endoscopic and histologic changes. Stool samples were collected at baseline and 4 weeks post-FMT to assess bacterial microbiota using V4 16S rRNA sequencing. RESULTS: Nineteen patients were enrolled; however, 1 patient was lost to follow-up. No patients had a major adverse event or escalation of therapy related to FMT. Total PDAI scores, endoscopic scores, and histologic scores did not decrease significantly post-FMT. However, there was a statistically significant improvement in bowel movement (BM) frequency (9.25-7.25 BM/day, p = 0.03) and trend for improvement in abdominal pain to improve post-FMT (p = 0.05). Bacterial microbiota profiling revealed no distinct community-level changes post-FMT, though a small number of specific bacterial taxa significantly differed in relative abundance. CONCLUSIONS: A single FMT has a tolerable short-term safety profile and may be associated with a decrease in bowel movements in patients with chronic pouchitis; however, no robust endoscopic or histologic changes were observed.

Blockade of RGMb inhibits allergen-induced airways disease.

BACKGROUND: Allergic asthma causes morbidity in many subjects, and novel precision-directed treatments would be valuable. OBJECTIVE: We sought to examine the role of a novel innate molecule, repulsive guidance molecule b (RGMb), in murine models of allergic asthma. METHODS: In models of allergic asthma using ovalbumin or cockroach allergen, mice were treated with anti-RGMb or control mAb and examined for airway inflammation and airway hyperreactivity (AHR), a cardinal feature of asthma. The mechanisms by which RGMb causes airways disease were also examined. RESULTS: We found that blockade of RGMb by treatment with anti-RGMb mAb effectively blocked the development of airway inflammation and AHR. Importantly, blockade of RGMb completely blocked the development of airway inflammation and AHR, even if treatment occurred only during the challenge (effector) phase. IL-25 played an important role in these models of asthma because IL-25 receptor-deficient mice did not develop disease after sensitization and challenge with allergen. RGMb was expressed primarily by innate cells in the lungs, including bronchial epithelial cells (known producers of IL-25), activated eosinophils, and interstitial macrophages, which in the inflamed lung expressed the IL-25 receptor and produced IL-5 and IL-13. We also found that neogenin, the canonical receptor for RGMb, was expressed by interstitial macrophages and bronchial epithelial cells in the inflamed lung, suggesting that an innate RGMb-neogenin axis might modulate allergic asthma. CONCLUSIONS: These results demonstrate an important role for a novel innate pathway in regulating type 2 inflammation in patients with allergic asthma involving RGMb and RGMb-expressing cells, such as interstitial macrophages and bronchial epithelial cells. Moreover, targeting this previously unappreciated innate pathway might provide an important treatment option for allergic asthma.

Genomic profiling of well-differentiated hepatocellular neoplasms with diffuse glutamine synthetase staining reveals similar genetics across the adenoma to carcinoma spectrum.

Well-differentiated hepatocellular neoplasms are currently classified in the World Health Organization scheme as hepatocellular adenoma or hepatocellular carcinoma. There is no recognized diagnostic category for atypical cases with borderline features, and we have designated these as atypical hepatocellular neoplasms. Diffuse glutamine synthetase staining is used as a surrogate marker to detect ß-catenin activation, a well-recognized high risk feature in hepatocellular tumors. This study examined 27 well-differentiated hepatocellular neoplasms with diffuse glutamine synthetase staining, including 7 atypical hepatocellular neoplasms with no cytoarchitectural atypia, 6 atypical hepatocellular neoplasms with focal cytoarchitectural atypia, and 14 well-differentiated hepatocellular carcinomas. Capture-based next-generation sequencing was performed, and alterations in WNT pathway genes (CTNNB1, APC, AXIN1) were seen in 81% of cases (10/13 atypical hepatocellular neoplasms and 12/14 of hepatocellular carcinomas), while the molecular basis of diffuse glutamine synthetase staining was unclear in the remaining 19% of cases. Additional non-WNT pathway mutations (TP53, TSC1, DNMT3A, CREBBP) or copy number alterations were present in 56% of atypical hepatocellular neoplasms, with no significant difference in cases with or without focal cytoarchitectural atypia, supporting that all cases with ß-catenin activation should be classified as atypical irrespective of atypia. Atypical hepatocellular neoplasm and hepatocellular carcinoma also demonstrated largely similar genomic profiles, but TERT promoter mutations were restricted to hepatocellular carcinoma (21%) and copy number alterations were more common in hepatocellular carcinoma (64 vs 31%). Mutational and copy number analysis may be helpful in characterization and risk stratification of atypical hepatocellular neoplasms when morphology and glutamine synthetase staining yield ambiguous results.

Identification of high-risk human papillomavirus and Rb/E2F pathway genomic alterations in mutually exclusive subsets of colorectal neuroendocrine carcinoma.

Colorectal neuroendocrine carcinomas, both small cell and large cell types, are highly aggressive tumors with poor prognosis compared with colorectal adenocarcinoma. The molecular drivers of neuroendocrine carcinoma are best defined in small cell lung cancer, which shows near-universal genomic alterations in TP53 and RB1. The genetics of colorectal neuroendocrine carcinoma remain poorly understood; recent studies demonstrated infrequent RB1 alterations and genetics closely resembling colorectal adenocarcinoma. To better define the molecular pathogenesis of colorectal neuroendocrine carcinoma, we performed capture-based next-generation sequencing on 25 cases and evaluated for expression of p53, Rb, p16, and high-risk human papillomavirus (HR-HPV) subtypes using immunohistochemistry, in situ hybridization, and polymerase chain reaction. Rb/E2F pathway dysregulation was identified in nearly all cases (23/25, 92%) and occurred via three distinct mechanisms. First, RB1 genomic alteration was present in 56% (14/25) of cases and was accompanied by Rb protein loss, high p16 expression, and absence of HR-HPV; these cases also had frequent genomic alterations in TP53, the PI3K/Ras and Wnt pathways, as well as in DNA repair genes, with 4/14 cases being hypermutated. Second, 16% (4/25) of cases, all left-sided, had TP53 alteration without RB1 alteration; half of these harbored high-level amplifications in CCNE1 and MYC or MYCN and arose in patients with ulcerative colitis. Finally, 28% (7/25) of cases, all rectal or anal, lacked genomic alterations in RB1 or TP53 but were positive for HR-HPV. Our data demonstrate that Rb/E2F pathway dysregulation is essential in the pathogenesis of colorectal neuroendocrine carcinoma, akin to neuroendocrine carcinomas in other anatomic sites. Moreover, colorectal neuroendocrine carcinomas stratify into three distinct molecular subgroups, which can be differentiated based on Rb protein and HR-HPV status. HR-HPV infection represents a distinct mechanism for Rb and p53 inactivation in cases lacking genomic alterations in either gene. Differential treatment strategies for hypermutated and HPV-driven cases could improve patient outcomes.

DNA flow cytometric and interobserver study of crypt cell atypia in inflammatory bowel disease.

AIMS: The pathological features and diagnostic reliability of crypt cell atypia (CCA) arising in inflammatory bowel disease (IBD) and its clinical significance are unknown. METHODS AND RESULTS: DNA flow cytometry (FCM) was performed on 14 colon biopsies of CCA from seven IBD patients (male-to-female ratio, 5:2; mean age, 53 years; mean IBD duration, 15 years) using paraffin-embedded tissue. Seven gastrointestinal pathologists were asked to diagnose each biopsy as negative for dysplasia (NEG), indefinite for dysplasia (IND), low-grade dysplasia (LGD) or high-grade dysplasia (HGD) by morphology alone, then again with knowledge of FCM results. Aneuploidy was detected in all 14 biopsies, and five of eight biopsies (63%) also showed strong and diffuse nuclear staining for p53 in the areas of CCA. Six (86%) patients developed HGD (n = 5) or adenocarcinoma (n = 1) in the same colonic segment where CCA had been diagnosed within a mean follow-up time of 27 months. No follow-up information was available in the remaining one patient. When diagnoses were grouped as NEG or 'atypical' (including IND, LGD or HGD), the overall agreement rate of 76% (kappa = 0.51) based on morphology alone improved to 90% (kappa = 0.81) with knowledge of FCM results. Even when categorised as NEG or dysplasia (LGD or HGD) with each of the IND diagnoses reclassified into three categories (NEG, LGD or HGD) based on the degree of suspicion for dysplasia, the overall agreement rate of 63% (kappa = 0.25) based on morphology alone improved to 73% (kappa = 0.46) with knowledge of FCM results. However, when grouped as NEG, LGD or HGD, the overall agreement rate was less than 40% (kappa < 0.09) regardless of knowledge of FCM results. CONCLUSIONS: The presence of aneuploidy, p53 positivity and development of HGD or adenocarcinoma on follow-up indicate that CCA likely represents a dysplastic lesion (at least LGD) and is a histological marker of neoplastic progression. Although the grading of CCA, largely based on cytological abnormalities, is subject to significant interobserver variability, CCA can be histologically identified and should lead to a recommendation of increased endoscopic surveillance, especially if aneuploidy is detected.

Hybrid Capture-Based Tumor Sequencing and Copy Number Analysis to Confirm Origin of Metachronous Metastases in BRCA1-Mutant Cholangiocarcinoma Harboring a Novel YWHAZ-BRAF Fusion.

Biliary tract cancers such as cholangiocarcinoma represent a heterogeneous group of cancers that can be difficult to diagnose. Recent comprehensive genomic analyses in large cholangiocarcinoma cohorts have defined important molecular subgroups within cholangiocarcinoma that may relate to anatomic location and etiology [1], [2], [3], [4] and may predict responsiveness to targeted therapies in development [5], [6], [7]. These emerging data highlight the potential for tumor genomics to inform diagnosis and treatment options in this challenging tumor type. We report the case of a patient with a germline BRCA1 mutation who presented with a cholangiocarcinoma driven by the novel YWHAZ-BRAF fusion. Hybrid capture-based DNA sequencing and copy number analysis performed as part of clinical care demonstrated that two later-occurring tumors were clonally derived from the primary cholangiocarcinoma rather than distinct new primaries, revealing an unusual pattern of late metachronous metastasis. We discuss the clinical significance of these genetic alterations and their relevance to therapeutic strategies. KEY POINTS: Hybrid capture-based next-generation DNA sequencing assays can provide diagnostic clarity in patients with unusual patterns of metastasis and recurrence in which the pathologic diagnosis is ambiguous.To our knowledge, this is the first reported case of a YWHAZ-BRAF fusion in pancreaticobiliary cancer, and a very rare case of cholangiocarcinoma in the setting of a germline BRCA1 mutation.The patient's BRCA1 mutation and YWHAZ-BRAF fusion constitute potential targets for future therapy.

Lack of Ikaros cripples expression of Foxo1 and its targets in naive T cells.

Ikaros is a transcription factor that regulates lymphocyte development from the level of the haematopoietic stem cell. Lack of Ikaros reduces the ability of progenitor cells to commit to the T-cell lineage, resulting in reduced numbers of early thymic T-cell progenitors and mature T cells. Mature CD4 T cells that lack Ikaros have defects in proliferation, T helper cell differentiation, cytokine expression and the ability to become anergic. A role for Ikaros in the naive T cell has not yet been identified. The receptors interleukin-7 receptor α (IL-7Rα) and l-selectin are important for ensuring survival and proper homing of naive T cells, respectively. Here we show that lack of Ikaros leads to reduced expression of these receptors in naive T cells, which impacts their ability to home and survive in response to IL-7. We define the mechanism underlying this phenotype as a requirement for Ikaros in maintenance of expression of Foxo1, a transcriptional regulator that is required for their expression. We also demonstrate that CD4 T cells lacking Ikaros are significantly crippled in their ability to become induced regulatory T cells, a phenotype also linked to reduced Foxo1 expression. Finally, we show that restoring Ikaros function to Ikaros-deficient CD4 T cells increases levels of Foxo1 message. Together, these studies define, for the first time, a role for Ikaros in naive T cells and establish it as the first transcriptional regulator required for maintaining levels of Foxo1 gene expression in these cells.

Recurrent GNAQ mutations in anastomosing hemangiomas.

Anastomosing hemangiomas are recently described benign vascular lesions that occur chiefly in the genitourinary tract and paravertebral soft tissues. Owing to their rarity and unusual cytoarchitectural features, anastomosing hemangiomas are frequently confused with low-grade angiosarcomas. The specific genetic alterations underlying these lesions are currently unknown. We performed capture-based next-generation DNA sequencing analysis on 13 anastomosing hemangiomas and identified frequent somatic mutations in the heterotrimeric G-protein alpha-subunit, GNAQ. Nine of 13 cases (69%) harbored a somatic mutation at GNAQ codon 209, a known hotspot that is commonly mutated in uveal melanoma and blue nevi, as well as various congenital vascular proliferations. No other pathogenic or likely pathogenic mutations were identified in these genetically simple lesions. The finding of a recurrent driver mutation in the G-protein signal transduction pathway provides strong evidence that anastomosing hemangiomas are indeed clonal vascular neoplasms.

Glutamine synthetase staining patterns in cirrhosis.

Advanced liver fibrosis can regress following the elimination of causative injuries. Glutamine synthetase (GS) immunohistochemical expression is normally in centrizonal perivenular hepatocytes but can be present in periportal hepatocytes in cases of regressed cirrhosis. This study identified periportal staining and investigated the spectrum of GS staining patterns seen in a range of cirrhotic livers with varying disease processes. The hematoxylin and eosin and GS-stained slides of 88 liver resection/explant specimens with advanced fibrosis cases by different causes were reviewed, and trichrome and orcein stains were used to classify cases as progressive, indeterminate, or regressive. Periportal GS staining was seen in 97% of regressive cases and 84% progressive or indeterminate cases. Liver resection specimens with periportal GS staining showed a variety of patterns, including predominantly perivenular, predominantly periseptal, and perinodular staining. The GS periseptal pattern is more common in regressed cirrhosis compared to progressive cases. The perinodular staining was seen in 16 cases resulting from various etiologies, including biliary atresia, steatotic liver disease, primary biliary cholangitis, and viral hepatitis, 75% of which demonstrated cholestasis. This study further subclassified GS staining patterns of "periportal" pattern in cirrhotic liver. Compared to orcein/trichrome staining, GS immunohistochemical staining is not as useful in distinguishing regressed cases from non-regressed cases.

Evaluating Liver Biopsies with Well-Differentiated Hepatocellular Lesions.

Needle core biopsies of liver lesions can be challenging, particularly in cases with limited material. The differential diagnosis for well-differentiated hepatocellular lesions includes focal nodular hyperplasia, hepatocellular adenoma, and well-differentiated hepatocellular carcinoma (HCC) in noncirrhotic liver, while dysplastic nodules and well-differentiated HCC are the primary considerations in cirrhotic liver. The first part of this review focuses on histochemical and immunohistochemical stains as well as molecular assays that are useful in the differential diagnosis. The second portion describes the features of hepatocellular adenoma subtypes and focuses on the differential diagnoses in commonly encountered clinicopathologic scenarios.