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Objective This study was designed to evaluate the roles of microRNAs (miRNAs) in slow transit constipation (STC). Design All human tissue samples were from the muscularis externa of the colon. Expression of 372 miRNAs was examined in a discovery cohort of four patients with STC versus three age/sex-matched controls by a quantitative PCR array. Upregulated miRNAs were examined by quantitative reverse transcription qPCR (RT-qPCR) in a validation cohort of seven patients with STC and age/sex-matched controls. The effect of a highly differentially expressed miRNA on a custom human smooth muscle cell line was examined in vitro by RT-qPCR, electrophysiology, traction force microscopy, and ex vivo by lentiviral transduction in rat muscularis externa organotypic cultures. Results The expression of 13 miRNAs was increased in STC samples. Of those miRNAs, four were predicted to target SCN5A , the gene that encodes the Na + channel Na V 1.5. The expression of SCN5A mRNA was decreased in STC samples. Let-7f significantly decreased Na + current density in vitro in human smooth muscle cells. In rat muscularis externa organotypic cultures, overexpression of let-7f resulted in reduced frequency and amplitude of contraction. Conclusions A small group of miRNAs is upregulated in STC, and many of these miRNAs target the SCN5A-encoded Na + channel Na V 1.5. Within this set, a novel Na V 1.5 regulator, let-7f, resulted in decreased Na V 1.5 expression, current density and reduced motility of GI smooth muscle. These results suggest Na V 1.5 and miRNAs as novel diagnostic and potential therapeutic targets in STC.

INTRODUCTION: Colorectal cancer (CRC) screening is broadly endorsed for individuals 50–75 years of age. Given recent increases in CRC incidence and mortality for patients <50 years old, the American Cancer Society now recommends initiation of average-risk CRC screening at age 45 (Wolf AMD CA Cancer J Clin 2018). The performance of recommended tests, including the multi-target stool DNA (mt-sDNA; marketed as Cologuard™) test, has been minimally described in populations under 50 years old. To address this knowledge gap, we conducted a retrospective study of DNA markers (KRAS, BMP3, NDRG4) included in the mt-sDNA assay to quantify and compare tissue marker levels in sporadic CRC cases and normal colon controls from patients in 45–49 and 50–64 year-old age groups. Our primary hypothesis was that mt-sDNA marker levels would be statistically similar between cases in both age groups. METHODS: Patient samples were identified from a pathology tissue archive at Mayo Clinic, excluding those with inflammatory bowel disease or familial cancer syndromes. Formalin-fixed, paraffin-embedded tissues were reviewed by a GI pathologist for 45–49 year-old (n = 90) and 50–64 year-old (n = 96) CRC cases; normal colon samples (45–49, n = 76; 50–64, n = 92) were also included for comparison. DNA extracted from core punches was blinded and processed in a randomized order. Quantitative Allele specific Realtime Target and Signal amplification (QuARTS) assays were used to quantify KRAS mutations, and BMP3 and NDRG4 methylation. Marker level in each sample was reported as the QuARTS product of mutant KRAS , methylated BMP3 or NDRG4 relative to the ACTB product in each sample, reported as a percentage. At least 60 patients per group provided sufficient power to demonstrate differences in marker levels of ±25% between case groups and between control groups using the Wilcoxon Rank Sum test. RESULTS: CRC cases in the 45–49 vs 50–64 year-old groups did not differ significantly with respect to sex ( P = 0.77) or race/ethnicity ( P = 0.06); left-sided CRC was more common in the 45–49 vs 50–64 year-old group (87% vs. 72%; P = 0.02). None of the marker levels were statistically different between cases of the younger vs older groups or between controls of these groups (Figure 1). CONCLUSION: These data support the expectation of no age-related differences in CRC detection by mt-sDNA, as the relevant molecular markers, when they occur, are present at similar levels across age groups 45–49 and 50–64 years.

Background Pancreatoblastoma (PBL) is a rare malignant pancreatic tumor seen predominantly in childhood, and its cytologic diagnosis remains challenging. Methods Twelve fine‐needle‐aspirations from 11 adults were analyzed. Results In total, 6 men and 5 women (median age, 45 years; age range, 32‐60 years) had tumors measuring a median 5.6 cm (range, 2.5‐12 cm) located in the pancreatic head (n = 7) or tail (n = 4), including 3 with familial adenomatous polyposis (FAP)/FAP‐related syndromes and 4 with metastasis at diagnosis. The median follow‐up was 39.8 months (range, 0.8‐348 months), and 5 patients died of disease. The original cytology diagnoses were: PBL (n = 2), neuroendocrine neoplasm (n = 2), poorly differentiated neuroendocrine carcinoma (n = 2), well differentiated neuroendocrine tumor (n = 1), poorly differentiated carcinoma (n = 2), “positive for malignancy” (n = 1), acinar cell carcinoma (n = 1), and epithelioid neoplasm with endocrine and acinar differentiation versus PBL (n = 1). Universal cytopathologic findings included hypercellularity; 3‐dimensional clusters; and single, monotonous, blast‐like cells that were from 1.5 to 2.0 times the size of red blood cells with high nuclear‐to‐cytoplasmic ratio, fine chromatin, small, distinct nucleoli, and a resemblance to well differentiated neuroendocrine tumor and poorly differentiated neuroendocrine carcinoma. Branching pseudopapillae (n = 7) and grooved nuclei (n = 3) raised the differential diagnosis of solid‐pseudopapillary neoplasm, but with more atypia. Uncommon features included pleomorphism (n = 4) and numerous mitoses (n = 1). Squamoid morules were seen on smears (n = 5) or cell blocks (n = 6) in 70% of patients and were characterized by epithelioid cells with elongated, streaming nuclei, fine chromatin, absent nucleoli, and positive nuclear β‐catenin (n = 6 of 8). The median Ki‐67 index was 21% (range, 2%‐70%), and neuroendocrine marker expression was common (100%), but acinar markers were variable (63%). Conclusions A combination of cytologic findings in PBL, including a predominant population of primitive blast‐like cells, subtle squamoid morules, frequent neuroendocrine and variable acinar phenotype, should facilitate accurate cytologic diagnosis and distinction from common mimics.

BackgroundHepatocellular carcinoma (HCC) rarely involves the biliary tree and may be inadvertently sampled on bile duct brushings (BDBs).MethodsThe pathology archives of 5 institutions were searched for BDBs with HCC involvement.ResultsA total of 17 BDBs from 14 patients were obtained. There was a male:female ratio of 6:1; the median age of the patients was 59.5 years (range, 22‐80 years). The median hepatic tumor size was 6.2 cm (range, 2.2‐13.0 cm). HCC risk factors included viral hepatitis (5 patients), cirrhosis (5 patients), hemochromatosis (1 patient), and alcoholic steatohepatitis (1 patient). Jaundice with elevated bilirubin, liver enzymes, and α‐fetoprotein was common. Endoscopic retrograde cholangiopancreatography demonstrated bile duct dilatation, polypoid intraductal masses (5 samples), clots/debris (2 samples), or strictures (4 samples). All BDBs had single and clustered large cells with naked atypical nuclei, granular cytoplasm, high nuclear/cytoplasmic ratios, and nuclei with prominent macronucleoli. Less common findings included clear/microvesicular cytoplasm (35%), papillae (29%), and anisonucleosis (35%). Classic HCC features (widened trabeculae [35%], endothelial wrapping [24%], multinucleation [24%], and cytoplasmic bile pigment [35%]) were uncommon. A total of 11 BDBs were diagnosed as malignant (10 with HCC and 1 with cholangiocarcinoma), 2 were diagnosed as atypical, and 1 BDB was diagnosed as negative; approximately two‐thirds were found to have polysomy on fluorescence in situ hybridization. Approximately 71% of patients died of disease at a median of 3.5 months.ConclusionsHCC may extend into the intrahepatic and/or extrahepatic biliary tree, causing masses and/or strictures that may be sampled on BDB. Although cytologically malignant, the classic features of HCC are uncommon, which can cause misdiagnosis. Cytopathologists should be mindful of this differential when evaluating BDBs, particularly when concomitant liver masses and/or HCC risk factors are present. Because of the associated high mortality and rapid rate of death, its presence should be conveyed clearly in pathology reports.

Epithelioid hemangioendothelioma (EHE) is an uncommon low-grade malignant vascular tumor that may arise in soft tissue/bone or visceral sites such as the liver and lung. As this tumor exhibits epithelioid morphology, it frequently causes diagnostic confusion with other epithelioid vascular neoplasms as well as carcinoma. While 90% of classic EHE are driven by aWWTR1-CAMTA1fusion gene, a histologically distinctive subset of EHE has been recently shown to harbor a different fusion gene,YAP1-TFE3. This variant is likely underrecognized given its rarity and only recent description. Notably, EHE frequently involves the liver but only one case of hepaticYAP1-TFE3rearranged EHE has been reported to date. We present the second case ofYAP1-TFE3rearranged EHE affecting a 65-year-old woman and presenting as multiple liver masses, with characterization of the fusion gene at the transcriptomic and genomic levels. There are several educational points noted from this case.YAP1-TFE3rearranged EHE shows distinctly vasoformative foci, unlike classic EHE and mimicking angiosarcoma or epithelioid hemangioma. The tumors cells show a histiocytoid appearance with voluminous cytoplasm, similar to otherTFE3-rearranged tumors. Finally, in the liver, this tumor may in part mimic focal nodular hyperplasia of the liver which is an underrecognized diagnostic pitfall. This report highlights the key diagnostic and genetic features of this newly recognized variant of hepatic EHE to aid pathologists in appropriately classifying these tumors.

3557 Background: The goal of this study was to evaluate the safety, tolerability and immunogenicity of a single dose of PolyPEPI1018 as an add-on to maintenance therapy in subjects with metastatic colorectal cancer (mCRC). PolyPEPI1018 is a peptide vaccine containing 12 unique epitopes derived from 7 conserved cancer testis antigens (CTAs) frequently expressed in mCRC. These epitopes were designed to be Personal EPItopes (PEPIs), i.e. predicted by our novel PEPI test to bind to at least three autologous HLA alleles and more likely to induce T-cell responses than epitopes presented by a single HLA. Methods: mCRC patients in the first line setting received the vaccine (dose: 0.2 mg/peptide) just after the transition to maintenance therapy with a fluoropyrimidine and bevacizumab. Vaccine-specific T-cell responses were first predicted by the PEPI test (using the patient’s complete HLA genotype and antigen expression rate) and then measured by ELISpot after one cycle of vaccination. Results: Eleven patients were vaccinated with PolyPEPI1018. The most common adverse events were transient skin reactions (local inflammation at the site of the injections, e.g. erythema, redness and itchiness) and flu-like syndrome. No grade 3 or higher adverse events related to the vaccine occurred. Initial analysis on 4 patients demonstrated that T-cell responses were elicited by 96% of vaccine peptides. The overall percentage agreement between PEPI test-predicted and Elispot-measured CD8+ T cell responses was 71%, consistent with our retrospective analysis on 64 vaccine clinical trials involving 1,790 patients. Two of these 4 patients had unexpected tumor size reduction. Based on these encouraging results, the trial was amended to administer 3 doses of PolyPEPI1018 given 12 weeks apart. Conclusions: PolyPEPI1018 combined with maintenance therapy was safe and well-tolerated in mCRC patients. Unprecedented immune responses were induced after single dose, with broad CRC-specific T cell responses and high accuracy prediction of CD8+ T cell responses. This promising activity in mCRC patients led to a trial amendment to administer 3 doses of PolyPEPI1018 in combination with systemic therapy. Clinical trial information: NCT03391232.

Hepatocellular adenomas (HCAs) often pursue an innocuous clinical course. Recent work has elucidated important subtypes of HCA and biomarkers to identify them, including HCA at an increased risk for malignant transformation. Another key complication of HCAs is the risk of spontaneous tumoral hemorrhage, which may be life-threatening. Identification of a predictive biomarker for this clinical complication would therefore be of clinical value. It has been suggested that Argininosuccinate Synthase 1 (ASS1) immunohistochemistry (IHC) identifies HCA with a high propensity for hemorrhage. The aim of our study was to validate ASS1 IHC as a predictive marker of hemorrhage. Eighty-nine HCAs were collected for ASS1 IHC and subtyped according to published criteria. Clinical records were examined for evidence of tumoral hemorrhage. Twenty-one (23.6%) HCAs were complicated by clinically detected hemorrhage and were more likely to be resected (P=0.0002). Hemorrhage complicated all WHO subtypes of HCA. There was no association between hemorrhage and HCA subtype (P=0.92). Neither the distribution of ASS1 expression nor the intensity of ASS1 expression compared to normal liver showed a significant association with hemorrhage (P=0.051 and 0.34). Interlaboratory comparison of 8 cases showed good agreement regarding the intensity (6/8 and 7/8) and distribution of staining (7/8 and 7/8) across 3 laboratories performing ASS1 IHC. In conclusion, all subtypes of HCA may be complicated by hemorrhage. ASS1 IHC expression did not correlate with hemorrhagic complications. Caution is prudent before routine implementation of ASS1 IHC in clinical practice.

AbstractAimColon ischaemia (CI) is most commonly an acute and reversible manifestation of a transient, non‐occlusive decrease of blood flow in the colonic microvasculature. Irreversible complications are uncommon and the progression to chronic CI remains controversial. Our objective was to identify cases of chronic CI and assess for distinct clinicopathological features.MethodA retrospective review was performed of CI patients having symptom chronicity of ≥ 1 month and ischaemic histology at our institution from 1994 to 2015. Demographic, clinical, endoscopic, radiological, pathological and outcome variables were abstracted. Histological evaluation was performed by two gastrointestinal pathologists.ResultsFifteen patients (n = 9; 67% men) with a median age of 65 years (range 22–88) were identified. The most common presenting symptoms were diarrhoea and abdominal pain (n = 6, 86%; n = 5, 71%, respectively). The typical endoscopic appearance was segmental ulceration of the sigmoid colon (n = 6, 75%). Vascular imaging showed patent mesenteric vessels in all patients. Histopathological evaluation revealed venous intimal hyperplasia consistent with idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) in eight patients; the remainder showed non‐specific ulceration and fibrosis. Surgical resection was performed in seven IMHMV patients, resulting in symptom resolution. On re‐review of pre‐resection biopsies, all IMHMV patients had characteristic changes of hyperplastic, thick‐walled, hyalinized vessels in the lamina propria.ConclusionsIMHMV is a unique histopathological entity causing chronic CI. The small vessel histological changes in IMHMV are distinctive in colonic resections and undetectable by routine vascular imaging. Preoperative diagnosis of IMHMV is possible with endoscopic biopsy and segmental colon resection is curative.

ABSTRACT Objectives Albumin messenger RNA (mRNA) expression is a marker of hepatocellular differentiation. Most published data are from review of tissue microarrays, and albumin in situ hybridization (ISH) expression across several tumor types is incompletely characterized. Methods Sections from 221 tumors were evaluated for albumin mRNA. Immunohistochemistry was used to confirm diagnoses. Albumin ISH was performed according to manufacturer-provided instructions. Fifty-nine cases were evaluated with both commercial ISH assays. Results Albumin mRNA was detected in all hepatocellular carcinomas (HCCs) and 81% of intrahepatic cholangiocarcinomas. Lung (20%), gallbladder (39%), hepatoid pancreatic (n = 1 of 1) adenocarcinoma, breast invasive ductal carcinoma (18%), yolk sac tumor (25%), and acinar cell carcinoma (29%) showed expression. Both assays were concordant in 93% of cases. Conclusions Albumin ISH was expressed in all HCCs studied. It was also positive in intrahepatic cholangiocarcinoma and patchy positive in gallbladder adenocarcinoma and a subset of other neoplasms, which can be a potential pitfall.

AimActivation of PKR‐like endoplasmic reticulum kinase (PERK), an endoplasmic reticulum stress sensor, is a feature of non‐alcoholic steatohepatitis (NASH), yet regulators of PERK signaling remain undefined in this context. The protein p58IPK regulates PERK; however, its role in NASH has not been examined. The aim of this study was to assess the in vivo role of p58IPK in the pathogenesis of dietary NASH.MethodsParameters of hepatocyte cell death, liver injury, inflammation, fibrosis, indirect calorimetry and PERK activation were assessed in p58IPK knockout (p58ipk−/−) mice and their wild‐type littermate controls. All animals were fed a diet enriched in fat, fructose, and cholesterol (FFC) for 20 weeks.ResultsActivation of PERK was attenuated in FFC‐fed p58ipk−/− mice. Accordingly, FFC‐fed p58ipk−/− mice showed a reduction in hepatocyte apoptosis and death receptor expression, with a significant reduction in serum alanine transaminase values. Correspondingly, macrophage accumulation and fibrosis were significantly lower in FFC‐fed p58ipk−/− mice.ConclusionWe have shown that, in an in vivo dietary NASH model, p58IPK mediates hepatocyte apoptosis and liver injury, likely through PERK phosphorylation. In the absence of p58IPK, PERK phosphorylation and NASH are attenuated. Inhibition of hepatic p58IPK could be a future target for NASH therapy.