Hepatic Adenomas in Patients 60 and Older Are Enriched for HNF1A Inactivation and Malignant Transformation.

Hepatic adenomas occur most commonly in women between the ages of 20 and 40 years, but rarely they occur in older aged persons, including those 60 years of age or older. This group of adenomas, however, has not been systemically examined. Twenty-six hepatic adenomas in persons 60 years of age or older were studied, along with a control group of 50 hepatic adenomas in persons aged 30 to 39. Hepatic adenomas in persons 60 or more years of age were found in 21 women and 5 men, while the control group had 44 women and 6 men. Subtyping the adenomas in persons 60 years or older showed the following results: 18 HNF1A-inactivated adenomas (69%), 4 inflammatory adenomas (15%), and 4 unclassified adenomas (15%). In contrast, the control group showed a significantly different pattern (P=0.003), with a greater percentage of inflammatory adenomas (28, 56%), fewer HNF1A-inactivated adenomas (8, 16%), and more unclassified adenomas (14, 28%). Atypia and malignant transformation within the hepatic adenomas was studied next. Of the hepatic adenomas in persons age 60 or greater, 3 (12%) showed atypical histologic features, and 6 (23%) had a malignant transformation. In contrast, for hepatic adenomas in the control group, only 4 (8%) adenomas showed atypical histologic features, and 3 (6%) had undergone malignant transformation. In addition, the hepatic adenomas that were atypical or showed early malignant transformation were less likely to have beta-catenin activation in patients over 60 (2/9 cases) compared with those between 30 and 39 years (5/7 cases). Myxoid change and heavy lipofuscin deposition were also more common in adenomas in older aged persons. In conclusion, hepatic adenomas in persons 60 years of age or older are enriched for HNF1A-inactivated adenomas and have a higher frequency of malignant transformation. Malignant transformation, however, is less likely to develop through activation of the beta-catenin pathway.

Morphologic and Molecular Findings in Myxoid Hepatic Adenomas.

Myxoid hepatic adenomas are a rare subtype of hepatic adenomas with distinctive deposition of extracellular myxoid material between the hepatic plates. A total of 9 cases were identified in 6 women and 3 men with an average of 59±12 years. The myxoid adenomas were single tumors in 5 cases and multiple in 4 cases. In 1 case with multiple adenomas, the myxoid adenoma arose in the background of GNAS-mutated hepatic adenomatosis. Myxoid hepatic adenomas had a high frequency of malignant transformation (N=5 cases). They were characterized at the molecular level by HNF1A inactivating mutations, leading to loss of LFABP protein expression. In addition, myxoid adenomas had recurrent mutations in genes within the protein kinase A (PKA) pathway or in genes that regulate the PKA pathway: GNAS, CDKN1B (encodes p27), and RNF123. In sum, myxoid adenomas are rare, occur in older-aged persons, have a high risk of malignant transformation, and are characterized by the combined inactivation of HNF1A and additional mutations that appear to cluster in the PKA pathway.

A Genome-First Approach to Characterize DICER1 Pathogenic Variant Prevalence, Penetrance, and Phenotype.

Importance: Genetic disorders are historically defined through phenotype-first approaches. However, risk estimates derived from phenotype-linked ascertainment may overestimate severity and penetrance. Pathogenic variants in DICER1 are associated with increased risks of rare and common neoplasms and thyroid disease in adults and children. This study explored how effectively a genome-first approach could characterize the clinical traits associated with germline DICER1 putative loss-of-function (pLOF) variants in an unselected clinical cohort. Objective: To examine the prevalence, penetrance, and phenotypic characteristics of carriers of germline DICER1 pLOF variants via genome-first ascertainment. Design, Setting, and Participants: This cohort study classifies DICER1 variants in germline exome sequence data from 92 296 participants of the Geisinger MyCode Community Health Initiative. Data for each MyCode participant were used from the start of the Geisinger electronic health record to February 1, 2018. Main Outcomes and Measures: Prevalence of germline DICER1 variation; penetrance of malignant tumors and thyroid disease in carriers of germline DICER1 variation; structured, manual review of electronic health records; and DICER1 sequencing of available tumors from an associated cancer registry. Results: A total of 92 296 adults (mean [SD] age, 59 [18] years; 98% white; 60% female) participated in the study. Germline DICER1 pLOF variants were observed in 1 in 3700 to 1 in 4600 participants, more than double the expected prevalence. Malignant tumors (primarily thyroid carcinoma) were observed in 4 of 25 participants (16%) with DICER1 pLOF variants, which is comparable (by 50 years of age) to the frequency of neoplasms in the largest registry- and clinic-based (phenotype-first) DICER1 studies published to date. DICER1 pLOF variants were significantly associated with risks of thyroidectomy (odds ratio [OR], 6.0; 95% CI, 2.2-16.3; P = .007) and thyroid cancer (OR, 9.2; 95% CI, 2.1-34.7; P = .02) compared with controls, but there was not a significant increase in the risk of goiter (OR, 1.8; 95% CI, 0.7-4.9). A female patient in her 80s who was a carrier of a germline DICER1 hotspot variant was apparently healthy on electronic health record review. The term DICER1 did not appear in any of the medical records of the 25 participants with a pLOF DICER1 variant, even in those affected with a known DICER1-associated tumor or thyroid phenotype. Conclusions and Relevance: This cohort study was able to ascertain individuals with germline DICER1 variants based on a genome-first approach rather than through a previously established DICER1-related phenotype. Use of the genome-first approach may complement more traditional approaches to syndrome delineation and may be an efficient approach for risk estimation.

SMARCA4/SMARCA2-deficient Carcinoma of the Esophagus and Gastroesophageal Junction.

Undifferentiated carcinoma of the esophagus and gastroesophageal junction is a recently recognized entity in the fifth edition of the World Health Organization Classification of Digestive Tumors and is diagnostically challenging, particularly on small biopsies. SMARCA4 and SMARCA2 are chromatin remodeling genes with key roles in oncogenesis. We retrieved 14 cases of SMARCA4/SMARCA2-deficient undifferentiated carcinoma of the gastroesophageal junction and esophagus from the authors' institutions. The tumors showed similar histologic findings: the sheet-like proliferation of tumor cells characterized by discohesion, large nuclei, and prominent macronucleoli with many tumor cells exhibiting a rhabdoid appearance. In 8 cases, adjacent specialized intestinal metaplasia was noted and 3 cases exhibited adjacent high-grade dysplasia. Immunohistochemically, tumors variably expressed keratins and disclosed loss of expression of SMARCA4 in 12 and SMARCA2 in 7 cases. In 2 cases SMARCA2 alone was lost without SMARCA4 loss. A mutant p53 immunohistochemical pattern was seen in 4 of 4 cases, 3 of which showed diffuse, strong nuclear expression, and 1 case displayed a complete loss of nuclear expression of p53, including invasive carcinoma and associated dysplasia, when present. Limited clinical follow-up was available, but 3 patients died of disease within 0.6, 2, and 7 months of diagnosis. We present the first series of undifferentiated carcinoma of the esophagus and gastroesophageal junction with this characteristic morphology associated with loss of SMARCA4 and/or SMARCA2 expression. This tumor type likely arises from dedifferentiation of a lower grade carcinoma in some cases, and Barrett esophagus and appears to be associated with an aggressive clinical course.

Ahr-Foxp3-RORγt axis controls gut homing of CD4+ T cells by regulating GPR15.

The orphan chemoattractant receptor GPR15 is important for homing T lymphocytes to the large intestine, thereby maintaining intestinal immune homeostasis. However, the molecular mechanisms underlying the regulation of GPR15 expression remain elusive. Here, we show a central role of the aryl hydrocarbon receptor (Ahr) in promoting GPR15 expression in both mice and human, thus gut homing of T lymphocytes. Mechanistically, Ahr directly binds to open chromatin regions of the Gpr15 locus to enhance its expression. Ahr transcriptional activity in directing GPR15 expression was modulated by two transcription factors, Foxp3 and RORγt, both of which are expressed preferentially by gut regulatory T cells (Tregs) in vivo. Specifically, Foxp3 interacted with Ahr and enhanced Ahr DNA binding at the Gpr15 locus, thereby promoting GPR15 expression. In contrast, RORγt plays an inhibitory role, at least in part, by competing with Ahr binding to the Gpr15 locus. Our findings thus demonstrate a key role for Ahr in regulating Treg intestinal homing under the steady state and during inflammation and the importance of Ahr-RORγt-Foxp3 axis in regulating gut homing receptor GPR15 expression by lymphocytes.

Requirement of Mitochondrial Transcription Factor A in Tissue-Resident Regulatory T Cell Maintenance and Function.

Regulatory T cells (Tregs) are pivotal for immune suppression. Cellular metabolism is important for Treg homeostasis and function. However, the exact role of mitochondrial respiration in Tregs remains elusive. Mitochondrial transcription factor A (Tfam) is essential for mitochondrial respiration and controls mitochondrial DNA replication, transcription, and packaging. Here, we show that genetic ablation of Tfam in Tregs impairs Treg maintenance in non-lymphoid tissues in the steady state and in tumors. Tfam-deficient Tregs have reduced proliferation and Foxp3 expression upon glucose deprivation in vitro. Tfam deficiency preferentially affects gene activation in Tregs through regulation of DNA methylation, with enhanced methylation in the TSDR of the Foxp3 locus. Deletion of Tfam in Tregs affects Treg homing and stability, resulting in tissue inflammation in colitis, but enhances tumor rejection. Thus, our work reveals a critical role of Tfam-mediated mitochondrial respiration in Tregs to regulate inflammation and anti-tumor immunity.

Ikaros Inhibits Group 3 Innate Lymphoid Cell Development and Function by Suppressing the Aryl Hydrocarbon Receptor Pathway.

Group 3 innate lymphoid cells (ILC3s) expressing the transcription factor (TF) RORγt are important for the defense and homeostasis of host intestinal tissues. The zinc finger TF Ikaros, encoded by Ikzf1, is essential for the development of RORγt(+) fetal lymphoid tissue inducer (LTi) cells and lymphoid organogenesis, but its role in postnatal ILC3s is unknown. Here, we show that small-intestinal ILC3s had lower Ikaros expression than ILC precursors and other ILC subsets. Ikaros inhibited ILC3s in a cell-intrinsic manner through zinc-finger-dependent inhibition of transcriptional activity of the aryl hydrocarbon receptor, a key regulator of ILC3 maintenance and function. Ablation of Ikzf1 in RORγt(+) ILC3s resulted in increased expansion and cytokine production of intestinal ILC3s and protection against infection and colitis. Therefore, in contrast to being required for LTi development, Ikaros inhibits postnatal ILC3 development and function to regulate gut immune responses at steady state and in disease.

Dysplastic lesions in inflammatory bowel disease: molecular pathogenesis to morphology.

Context.-Inflammatory bowel disease (IBD) is a long-standing chronic active inflammatory process in the bowel with increased risk for the development of colorectal carcinoma. Several molecular events involved in chronic active inflammatory processes contribute to multistage progression of human cancer development, including reactive oxygen and nitrogen species, aberrant arachidonic acid metabolites and cytokines/growth factors, and immune dysfunction. These molecular events in IBD lead to genetic abnormality and promote aberrant cell proliferation, which further lead to epithelial changes encompassing a broad spectrum from inflammation-induced hyperplasia to dysplasia. Objective.-To review the (1) epidemiologic and molecular pathogenesis of the risk for colorectal cancer in IBD, (2) morphologic characterization, biomarker(s), and classification of dysplastic lesions, and (3) clinical management of dysplastic lesions arising in IBD. Data Sources.-The different IBD-related dysplastic lesions are illustrated by using morphology in conjunction with molecular pathways, and the "field cancerization" theory and its potential significance are discussed with a review of the literature. Conclusions.-Patients with IBD are at increased risk of developing colorectal cancer. The risk of developing carcinoma is related to the extent/duration/activity of the patient's disease. There is no consensus regarding the extent of carcinoma risk associated with IBD; however, all would agree that patients with IBD represent a group at significant risk for developing carcinoma and as such, warrant adequate surveillance and prevention. With better screening modalities and detection/characterization of dysplastic lesions, IBD-associated serrated lesions, and "field cancerization," we will improve our understanding of and approach to risk stratification.

Accuracy of MR elastography and anatomic MR imaging features in the diagnosis of severe hepatic fibrosis and cirrhosis.

PURPOSE: To compare the diagnostic accuracy of magnetic resonance imaging elastography (MRE) and anatomic MRI features in the diagnosis of severe hepatic fibrosis and cirrhosis. MATERIALS AND METHODS: Three readers independently assessed presence of morphological changes associated with hepatic fibrosis in 72 patients with liver biopsy including: caudate to right lobe ratios, nodularity, portal venous hypertension (PVH) stigmata, posterior hepatic notch, expanded gallbladder fossa, and right hepatic vein caliber. Three readers measured shear stiffness values using quantitative shear stiffness maps (elastograms). Sensitivity, specificity, and diagnostic accuracy of stiffness values and each morphological feature were calculated. Interreader agreement was summarized using weighted kappa statistics. Intraclass correlation coefficient was used to assess interreader reproducibility of stiffness measurements. Binary logistic regression was used to assess interreader variability for dichotomized stiffness values and each morphological feature. RESULTS: Using 5.9 kPa as a cutoff for differentiating F3-F4 from F0-2 stages, overall sensitivity, specificity, and diagnostic accuracy for MRE were 85.4%, 88.4%, and 87%, respectively. Overall interreader agreement for stiffness values was substantial, with an insignificant difference (P = 0.74) in the frequency of differentiating F3-4 from F0-2 fibrosis. Only hepatic nodularity and PVH stigmata showed moderately high overall accuracy of 69.4% and 72.2%. Interreader agreement was substantial only for PVH stigmata, moderate for C/R m, deep notch, and expanded gallbladder fossa. Only posterior hepatic notch (P = 0.82) showed no significant difference in reader rating. CONCLUSION: MRE is a noninvasive, accurate, and reproducible technique compared with conventional features of detecting severe hepatic fibrosis.

Diffusion-weighted MR imaging of solid and cystic lesions of the pancreas.

Diffusion-weighted magnetic resonance (MR) imaging is increasingly used in the detection and characterization of pancreatic lesions. Diffusion-weighted imaging may provide additional information to radiologists evaluating patients who have cystic or solid neoplasms of the pancreas. Because of greater freedom of motion of water molecules in fluid-rich environments, simple cysts in the pancreas have higher signal intensity on diffusion-weighted images with a b value of 0 sec/mm2 and lower signal intensity on high-b-value images. High apparent diffusion coefficient (ADC) values can be obtained on ADC maps because of the T2 "shine-through" effect. In contrast, solid neoplasms of the pancreas show increased signal intensity relative to the pancreas on diffusion-weighted images with a b value of 0 sec/mm2 and relatively high signal intensity on high-b-value images. Diffusion-weighted imaging can help detect solid pancreatic neoplasms with extremely dense cellularity or extracellular fibrosis by demonstrating significantly low ADC values, and these neoplasms may be better detected on diffusion-weighted MR images because of better contrast, although the resolution is generally worse. However, diffusion-weighted imaging may not be capable of helping definitively characterize solid lesions as inflammatory or neoplastic because of an overlap in ADC values between the two types. For example, it is difficult to distinguish poorly differentiated pancreatic adenocarcinoma from mass-forming pancreatitis at diffusion-weighted imaging because of similarly low ADC values attributed to dense fibrosis.

Diffusion-weighted MR imaging in pancreatic endocrine tumors correlated with histopathologic characteristics.

PURPOSE: To retrospectively assess apparent diffusion coefficients (ADCs) of different subtypes of pancreatic endocrine tumors based on the World Health Organization (WHO) classification system and analyze the potentially responsible histopathologic characteristics. MATERIALS AND METHODS: Following Institutional Review Board (IRB) approval, 18 patients with surgical pathology-proven pancreatic endocrine tumors were evaluated. Tumors were subcategorized based on the WHO grading classification into well-differentiated tumors with benign and uncertain behavior and endocrine carcinomas with well and poor differentiation. ADCs were measured on diffusion-weighted (DW) images and compared using Student's t-test and one-way analysis of variance. The correlation between ADCs, tumor cellularity, Ki-67 labeling index (an index of cell growth), and extracellular fibrosis were analyzed. RESULTS: A difference was demonstrated in mean ADCs between well-differentiated endocrine tumors (1.75 ± 0.53) and endocrine carcinomas (1.00 ± 0.19 × 10(-3) mm(2) /sec) (P < 0.01). After excluding the three well-differentiated endocrine tumors with benign behavior and marked fibrosis, a significant inverse correlation between ADC values and cellularity of endocrine tumors was observed. An inverse correlation was seen between Ki-67 labeling index and ADC values (r = -0.70; P < 0.01). CONCLUSION: Tumor cellularity and/or extracellular fibrosis may account for various ADCs in pancreatic endocrine tumors. ADC correlates well with the Ki-67 labeling index and may help predict growth of endocrine tumors.

Assessment of chronic hepatitis and fibrosis: comparison of MR elastography and diffusion-weighted imaging.

OBJECTIVE: The purpose of our study was to compare the utility of MR elastography (MRE) and diffusion-weighted imaging (DWI) in characterizing fibrosis and chronic hepatitis in patients with chronic liver diseases. SUBJECTS AND METHODS: Seventy-six patients with chronic liver disease underwent abdominal MRI, MRE, and DWI. Severities of liver fibrosis and chronic hepatitis were graded by histopathologic analysis according to standard disease-specific classifications. The overall predictive ability of MRE and DWI in assessment of fibrosis was compared by constructing a receiver operating characteristic (ROC) curve and calculating the area under the curve (AUC) on the basis of histopathologic analysis. RESULTS: Using ROC analysis, MRE showed greater capability than DWI in discriminating stage 2 or greater (≥ F2), stage 3 or greater (≥ F3), and cirrhosis (≥ F4), shown as significant differences in AUC (p = 0.003, p = 0.001, and p = 0.001, respectively). Higher sensitivity and specificity were shown by MRE in predicting fibrosis scores ≥ F2 (91% and 97%), scores ≥ F3 (92% and 95%), and scores F4 (95% and 87%) compared with DWI (84% and 82%, 88% and 76%, and 85% and 68%, respectively). Although MRE had higher ability in identification of liver with fibrosis scores ≥ F1 than DWI, a significant difference was not seen (p = 0.398). Stiffness values on MRE increased in relation to increasing severity of fibrosis confirmed by histopathology scores; however, a consistent relationship between apparent diffusion coefficient (ADC) values and stage of fibrosis was not shown. In addition, liver tissue with chronic hepatitis preceding fibrosis may account for mild elevation of liver stiffness. CONCLUSION: MRE had greater predictive ability in distinguishing the stages of liver fibrosis than DWI.

Diffusion-weighted magnetic resonance imaging of pancreatic adenocarcinomas: association with histopathology and tumor grade.

PURPOSE: To evaluate the utility of diffusion-weighted magnetic resonance imaging (DWI) in pancreatic ductal adenocarcinoma with various grades of differentiation. MATERIALS AND METHODS: Following Institutional Review Board (IRB) approval, 21 consecutive patients with surgical pathology-proven pancreatic adenocarcinomas were retrospectively evaluated. Histopathologic characteristics and grades of differentiation of adenocarcinomas were analyzed. Twenty-one patients without a known history of pancreatic disease were evaluated as the control group. Anatomic MR images and DW images were acquired using 1.5-T MR systems. DWI with b values of 0 and 500 sec/mm² were performed on both patients and control groups. The difference in mean apparent diffusion coefficient (ADC) values among groups of normal pancreatic parenchyma, adenocarcinomas with poor differentiation, and adenocarcinomas with well/moderate differentiation were compared using one-way analysis of variance. RESULTS: Mean ADCs of pancreatic adenocarcinomas (1.77 ± 0.45 × 10⁻³ mm²/sec) was not significantly lower than that of normal parenchyma (1.98 ± 0.31) (P = 0.09). When adenocarcinomas were subdivided based on grades of differentiation, however, poorly differentiated adenocarcinoma with histopathologic characteristics of limited glandular formation and dense fibrosis had significantly lower ADCs (1.46 ± 0.17) compared to those of well/moderately differentiated adenocarcinomas (2.10 ± 0.42) characterized by neoplastic tubular structures (P < 0.01). Well/moderately differentiated adenocarcinomas with dense fibrosis showed significantly lower ADC values (1.49 ± 0.19) than those with loose fibrosis (2.26 ± 0.30) (P = 0.01). CONCLUSION: Difference in ADC values using DWI between poorly and well/moderately differentiated pancreatic ductal adenocarcinoma may relate to differences in glandular formation and density of fibrosis.