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Not all populations are poised to benefit from advancing genomics in gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN), as genomics have focused on White patients. This study aimed to evaluate racial populations represented in genomic studies of GEP-NENs and to provide evidence of differential genomic findings between racial groups in GEP-NENs. Manuscripts analyzing DNA, RNA, or DNA methylation in GEP-NENs were queried using PUBMED and EMBASE. NIH race/ethnicity term frequency was then determined by Natural Language Processing, followed by manual evaluation of tumor types and subjects by racial group. IHC of institutional tissue micro-arrays and analysis of AACR GENIE data analyzed was performed to determine mutational differences between Black and White pancreatic NEN (pNEN) patients. 313 manuscripts conducted the requisite genomic analyses, 16 of which included subject race data. Race data were included in 13/184 DNA, 4/107 RNA, and 1/54 DNA Methylation analyses. These studies included 89% White subjects (n = 2032), 5.8% Asian subjects (n = 132), 4.0% “Other” subjects (n = 93), and 1.2% Black subjects (n = 27). No Native American/Alaska Native, Native Hawaiian/Pacific Islander, or ethnically Hispanic/Latinx subjects were represented. There were significant differences in MEN1 mutations among Black and White patients in immunohistochemical (13:40) and GENIE data (24:268 patients per group, respectively), with 9 additional genes differentially mutated in the GENIE dataset. Genomic sequencing data for GEP-NENs is almost racially homogenous. Differences in pNEN genomics may exist between racial groups, highlighting a need for diversity in future genomic analyses of GEP-NENs to understand the putative influence of interracial genomic variation on GEP-NEN prevention, diagnosis, and therapy. Significance: There is little diversity in genomic studies of GEP-NENs, which may exhibit clinically impactful variation in their tumor biology among racial groups. Improved diversity in such studies is imperative for understanding this variation and its potential impacts on disease prevention, diagnosis, therapeutic targeting, and clinical outcomes.

Structured Queries to PUBMED and EMBASE for Systematic Literature Review of GEP-NEN Genomics Studies.

Assays used to analyze biomolecules in the 16 studies of GEP-NENs that reported patient race.

Not all populations are poised to benefit from advancing genomics in gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN), as genomics have focused on White patients. This study aimed to evaluate racial populations represented in genomic studies of GEP-NENs and to provide evidence of differential genomic findings between racial groups in GEP-NENs. Manuscripts analyzing DNA, RNA, or DNA methylation in GEP-NENs were queried using PUBMED and EMBASE. NIH race/ethnicity term frequency was then determined by Natural Language Processing, followed by manual evaluation of tumor types and subjects by racial group. IHC of institutional tissue micro-arrays and analysis of AACR GENIE data analyzed was performed to determine mutational differences between Black and White pancreatic NEN (pNEN) patients. 313 manuscripts conducted the requisite genomic analyses, 16 of which included subject race data. Race data were included in 13/184 DNA, 4/107 RNA, and 1/54 DNA Methylation analyses. These studies included 89% White subjects (n = 2032), 5.8% Asian subjects (n = 132), 4.0% “Other” subjects (n = 93), and 1.2% Black subjects (n = 27). No Native American/Alaska Native, Native Hawaiian/Pacific Islander, or ethnically Hispanic/Latinx subjects were represented. There were significant differences in MEN1 mutations among Black and White patients in immunohistochemical (13:40) and GENIE data (24:268 patients per group, respectively), with 9 additional genes differentially mutated in the GENIE dataset. Genomic sequencing data for GEP-NENs is almost racially homogenous. Differences in pNEN genomics may exist between racial groups, highlighting a need for diversity in future genomic analyses of GEP-NENs to understand the putative influence of interracial genomic variation on GEP-NEN prevention, diagnosis, and therapy.Significance:There is little diversity in genomic studies of GEP-NENs, which may exhibit clinically impactful variation in their tumor biology among racial groups. Improved diversity in such studies is imperative for understanding this variation and its potential impacts on disease prevention, diagnosis, therapeutic targeting, and clinical outcomes.

AACR Genie Comparisons (SD.1), STRING Interactions (SD.2), GO Enrichment of STRING data (SD.3)

Context.— Claudin-18 is expressed in some gastric cancers. Clinical trials are evaluating it as a therapeutic target. Objectives.— To evaluate claudin-18 expression in intestinal metaplasia, dysplasia, and adenocarcinoma of the distal esophagus/gastroesophageal junction and stomach and to evaluate claudin-18 expression in gastric and nongastric neuroendocrine tumors as a marker of gastric origin. Design.— Samples included gastroesophageal junction with intestinal metaplasia (n = 40), dysplasia (n = 54), and adenocarcinoma (n = 20) and stomach with intestinal metaplasia (n = 79), dysplasia (n = 43), and adenocarcinoma (n = 25). Additionally, gastric (n = 40) and nongastric (n = 322) neuroendocrine tumors were included. Claudin-18 expression was evaluated for any staining as positive and by meeting clinical trial inclusion criteria (≥2+ intensity in ≥50% of tumor). Results.— Claudin-18 staining was not significantly different across dysplasia categories in the gastroesophageal junction (P = .11) or stomach (P = .12). The rate of positive staining was higher in gastroesophageal junction than stomach for intestinal metaplasia (37 of 40 [92.5%] versus 37 of 79 [46.8%]; P < .001) and high-grade dysplasia (33 of 38 [86.8%] versus 9 of 16 [56.3%]; P = .03). Intestinal metaplasia showed staining in 7 of 37 autoimmune gastritis samples (18.9%) compared with 30 of 42 samples without autoimmune gastritis (71.4%) (P < .001). Adenocarcinoma showed similar staining in gastroesophageal junction (15 of 20; 75.0%) and stomach (17 of 25; 68.0%) (P = .85). Eighty percent (32 of 40) of gastric neuroendocrine tumors were positive for claudin-18 expression, with 57.5% (23 of 40) meeting clinical trial inclusion criteria. Comparatively, 0.62% (2 of 322) of nongastric neuroendocrine tumors showed staining (P < .001). Conclusions.— Claudin-18 staining was similar in intestinal metaplasia, dysplasia, and adenocarcinoma. Claudin-18 was negative in most cases of intestinal metaplasia in autoimmune gastritis, indicating that intestinal metaplasia in this setting may differ from other forms. Claudin-18 was sensitive and specific for gastric origin in neuroendocrine tumors.

The utility of frozen section evaluation of the pancreatic parenchymal resection margin(s) in the surgical management of intraductal papillary mucinous neoplasm (IPMN) remains controversial. We investigated the frequency of its use in IPMN resections and its impact on achievement of negative final parenchymal margin(s).Sixty-two IPMN resections (11 with invasive carcinoma) performed over a 12-year period were studied.Frozen sections of the parenchymal margin(s) were performed on 44 of the 62 resections (71%), 30 (68%) of which had 10 positive and 22 indefinite margins on frozen section. Additional margin resections were performed in 14 of these 30 cases (47%), boosting the complete resection rate from 14% (2 of 14) on the initial margin(s) to 71% (10 of 14) on the final margin(s) (P = 0.002). Overall, negative final parenchymal margin(s) were achieved more frequently when evaluation of the initial margin(s) by frozen section was performed (35 of 44; 80%) than when it was not (11 of 18; 61%) (P = 0.13).In the intraoperative management of IPMN, frozen sections are highly reliable for margin evaluation and are useful for guiding the extent of pancreatic resection.

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous population of neoplasms that arise from hormone-secreting islet cells of the pancreas and have increased markedly in incidence over the past four decades. Non-functional PanNETs, which occur more frequently than hormone-secreting tumors, are often not diagnosed until later stages of tumor development and have poorer prognoses. Development of successful therapeutics for PanNETs has been slow, partially due to a lack of diverse animal models for pre-clinical testing. Here, we report development of an inducible, conditional mouse model of PanNETs by using a bi-transgenic system for regulated expression of the aberrant activator of Cdk5, p25, specifically in β-islet cells. This model produces a heterogeneous population of PanNETs that includes a subgroup of well-differentiated, non-functional tumors. Production of these tumors demonstrates the causative potential of aberrantly active Cdk5 for generation of PanNETs. Further, we show that human PanNETs express Cdk5 pathway components, are dependent on Cdk5 for growth, and share genetic and transcriptional overlap with the INS-p25OE model. The utility of this model is enhanced by the ability to form tumor-derived allografts. This new model of PanNETs will facilitate molecular delineation of Cdk5-dependent PanNETs and the development of new targeted therapeutics.

Despite the latest 8th edition American Joint Committee on Cancer Staging Manual guidelines, disagreement still exists among pathologists regarding staging deeply invasive colonic adenocarcinomas ≤1 mm to the serosal surface. In this retrospective study, 151 untreated colonic adenocarcinomas staged initially as either pT3 or pT4a and with available 5-year follow-up data were retrieved and re-categorized: Group 1 (38 cases): pT4a with tumor at the serosa; Group 2 (49 cases): tumor ≤1 mm from the serosa, with intervening reactive fibrosis (40/49) or inflammation (9/49); Group 3 (64 cases): pT3 tumor >1 mm from the serosa. Clinical outcomes were analyzed. Groups 1 and 2 tumors showed significantly lower 5-year recurrence-free survival and lower overall survival rates (log-rank p

Adult granulosa cell tumor (AGCT) is the most common sex cord-stromal tumor, accounting for about 1% of all ovarian tumors. It has a propensity for recurrences, especially late in the disease course. High-grade or sarcomatoid transformation has been rarely described in AGCT. We present a case of a 65 year old woman who presented with hemodynamic shock and bowel obstruction from a large pelvic mass. Histologic examination revealed predominantly high-grade epithelioid and spindled cells with high mitotic activity and necrosis. A minor component suggestive of AGCT was also identified. Molecular analysis confirmed the diagnosis of AGCT by revealing FOXL2 C134W mutations. Additionally, TP53 mutations were also detected which may contribute to the high-grade transformation. Our case is unique because the high-grade sarcomatous component constituted most of the tumor and the areas of “typical” AGCT were minor. Also, the clinical and operative findings did not suggest a specific site of origin leading to a broad differential diagnosis. High-grade transformation in AGCT is a rarely described phenomenon. The awareness of this presentation is helpful in reaching the correct diagnosis. Molecular analysis may be an extremely helpful adjunct in challenging cases.

Autoimmune gastritis (AIG) is a clinicopathologic diagnosis requiring characteristic histopathology and correlation with laboratory work-up. To better understand how the diagnosis of AIG is made and reported in the pathology community, we conducted an anonymous web-based survey which was circulated among a diverse group of pathologists. Excluding trainees there were 64 respondents: 25 academic gastrointestinal pathologists (AGI, 39%), 22 academic general pathologists (AGP, 34%), 17 private general pathologists (PP, 27%). Our survey results highlighted variations in work-up and sign-out practices. The type of metaplasia needed to diagnose AIG lacked consensus. There was variation in accurate interpretation of immunostains with a trend towards more accurate diagnosis of enterochromaffin-like (ECL) cell hyperplasia by AGI (92%) and AGP (95%) than PP (71%) (p = 0.07). G-cells in antrum on neuroendocrine immunostain, a mimicker of ECL cell hyperplasia, was more frequently misdiagnosed by PP/ AGP (44%), versus AGI (12%) (p = 0.02). A triple immunostain panel (H. pylori, neuroendocrine, gastrin) was used in the work-up of AIG by 72% of AGI versus 23% AGP and 12% PP (p = 0.000061). The less-specific term “atrophic gastritis” was used in the diagnostic line more by respondents with >10 years sign-out experience compared with others (p = 0.04). In conclusion, the survey results highlighted deficiencies in the interpretation of neuroendocrine immunostains which is crucial for AIG diagnosis, as well as variation in reporting practices and definitions. Uniform criteria and terminology are needed in this field to improve communication with clinicians, resulting in appropriate testing and follow-up.

In recent literature and international meetings held, it has become clear that there are significant differences regarding the definition of what constitutes as margins and how best to document the pathologic findings in pancreatic ductal adenocarcinoma. To capture the current practice, Pancreatobiliary Pathology Society (PBPS) Grossing Working Group conducted an international multispecialty survey encompassing 25 statements, regarding pathologic examination and reporting of pancreatic ductal adenocarcinoma, particularly in pancreatoduodenectomy specimens. The survey results highlighted several discordances; however, consensus/high concordance was reached for the following: (1) the pancreatic neck margin should be entirely submitted en face, and if tumor on the slide, then it is considered equivalent to R1; (2) uncinate margin should be submitted entirely and perpendicularly sectioned, and tumor distance from the uncinate margin should be reported; (3) all other surfaces (including vascular groove, posterior surface, and anterior surface) should be examined and documented; (4) carcinoma involving separately submitted celiac axis specimen should be staged as pT4. Although no consensus was achieved regarding what constitutes R1 versus R0, most participants agreed that ink on tumor or at and within 1 mm to the tumor is equivalent to R1 only in areas designated as a margin, not surface. In conclusion, this survey raises the awareness of the discordances and serves as a starting point towards further standardization of the pancreatoduodenectomy grossing and reporting protocols.

INTRODUCTION: The pediatric obesity epidemic is associated with early development of hepatic macrosteatosis, a hallmark of nonalcoholic fatty liver disease, which is thought to be more rapidly progressive in children than adults. Macrosteatosis in adult allografts is associated with allograft loss, but this has not been examined in pediatric donors. METHODS: We studied all pediatric potential whole liver donors (2005–2018) who had a liver biopsy in the Scientific Registry for Transplant Recipients (SRTR) (n=862) and whose liver was transplanted (n=862). Macrosteatosis was abstracted from biopsy reports and compared to values in the SRTR standard analytic file. Recipients of macrosteatotic pediatric allografts were matched 1:1 to recipients of non-macrosteatotic pediatric allografts by propensity score matching on donor/recipient variables. All-cause allograft loss was estimated via Kaplan-Meier analysis and Cox proportional hazards model. RESULTS: From 2005–2018, the proportion of pediatric donors (age≥2 years) with obesity increased (14.8% to 21.7%; P0.05). CONCLUSION: Obese pediatric liver donors have increased over time and were more likely to have hepatic macrosteatosis; however, pediatric macrosteatosis did not appear to adversely affect recipient outcomes.

Background. In this single-institution study, we applied the current (eighth edition) American Joint Committee on Cancer pathologic staging criteria to 64 low-grade mucinous neoplasms of the appendix (LAMNs), examined their histopathologic features, and studied the patients’ clinical outcomes. Design. Sixty-four LAMNs, with a median follow-up of 52 months, were reviewed. Results. The distribution of pathologic stages was pTis (n = 39), pT3 (n = 1), pT4a (n = 5), pT4aM1a (n = 8), and pT4aM1b (n = 11). Recurrence was observed in only 2 patients (both with pT4aM1b disease), one of whom died of disease. All remaining patients were disease-free after a median clinical follow-up of 60 months. Conclusions. Our study confirms that pTis LAMNs have an excellent prognosis and suggests that pT4a and pT4aM1a LAMNs may also have a low risk of developing progressive disease.

Background & Aims In the West, early gastric cancer is increasingly managed with endoscopic resection (ER). This is, however, based on the assumption that the low prevalence and risk of lymph node metastases observed in Asian patients is applicable to patients in the United States. We sought to evaluate the frequency of and factors associated with metastasis of early gastric cancers to lymph nodes, and whether the Japanese ER criteria are applicable to patients in the US. Methods We performed a retrospective study of 176 patients (mean age 68.5 years; 59.1% male; 58.5% white) who underwent surgical resection with lymph node dissection of T1 and Tis gastric adenocarcinomas, staged by pathologists, at 7 tertiary care centers in the US from January 1, 1999, through December 31, 2016. The frequency of lymph node metastases and associated risk factors were determined. Results The mean size of gastric adenocarcinomas was 23.0 ± 16.6 mm—most were located in the lower-third of the stomach (67.0%), invading the submucosa (55.1%), and moderately differentiated (31.3%). Lymphovascular invasion was observed in 18.2% of lesions. Overall, 20.5% of patients had lymph node metastases. Submucosal invasion (odds ratio, 3.9; 95% CI, 1.4–10.7) and lymphovascular invasion (odds ratio, 4.6; 95% CI, 1.8–12.0) were independently associated with increased risk of metastasis to lymph nodes. The frequency of lymph node metastases among patients fulfilling standard and expanded Japanese criteria for ER were 0 and 7.5%, respectively. Conclusions The frequency of lymph node metastases among patients with early gastric cancer in a US population is higher than that of published Asian series. However, early gastric cancer lesions that meet the Japanese standard criteria for ER are associated with negligible risk of metastasis to lymph nodes, so ER can be recommended for definitive therapy. Expanded criteria cancers appear to have a higher risk of metastasis to lymph nodes, so ER may be considered for select cases.

Liver biopsies are commonly performed in heart transplant candidates to confirm congestive hepatopathy (CH) and to assess the degree of fibrosis. Heterogeneity of fibrosis is frequent in CH, making it difficult to stage fibrosis. In this study, we evaluated the prevalence of heterogeneity of fibrosis and nodular regenerative hyperplasia (NRH) in liver biopsies with CH secondary to heart failure. Fifty liver biopsies with CH secondary to heart failure were reviewed. The fibrosis was scored on trichrome stain as follows: stage 0 for no fibrosis, stage 1 for zone 3 fibrosis, stage 2 for zone 3 and portal fibrosis, stage 3 for bridging fibrosis, and stage 4 for cirrhosis. Both stage 3 and stage 4 fibrosis were classified as advanced fibrosis. A predominant pattern of fibrosis and a secondary pattern of fibrosis, defined as a different stage of fibrosis seen in at least 10% of the biopsy material, if present, were recorded. A biopsy was considered to show heterogenous fibrosis if there was at least a 2 stage difference between the predominant and secondary patterns. Thirteen biopsies (26%) showed heterogenous fibrosis. Sixteen biopsies (32%) showed some evidence of advanced fibrosis: 5 had uniform advanced fibrosis, 4 had predominant pattern of advanced fibrosis, and advanced fibrosis was focal in 7 biopsies from 6 patients. NRH-type changes were seen in 9 of 50 biopsies (18%). In conclusion, our study showed heterogenous fibrosis in the liver biopsy of a quarter of patients with CH due to heart failure, highlighting the limitations of fibrosis assessment in the biopsies, and suggests that correlation with the complete clinical information is essential for management decisions.

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare primary and highly aggressive intestinal T-cell lymphoma derived from intraepithelial lymphocytes. MEITL is previously designated as type II enteropathy-associated T cell lymphoma (EATL). Unlike to classic form of EATL, MEITL is not associated with celiac disease. The diagnosis of MEITL is very challenging and the clinical outcome of patients with MEITL is very poor. Herein we describe a series of four patients diagnosed with MEITL identified upon a 10-year institutional retrospective review. Histopathologic examination of these cases revealed monotonous population of medium sized cells infiltrating intestinal mucosa, positive for CD3, CD8 and CD56 in all four cases. Two patients had the combination chemotherapy; however, the average survival time was only 7.5 months for these two patients after diagnosis. The aim of the present case series is to highlight the pathology, diagnosis and clinical course of the patients with MEITL based on the current literature.

Considerable confusion surrounds neuroendocrine neoplasms, as terminology and understanding of their biological behavior continues to evolve. In this chapter, a series of questions and answers is presented addressing what features define neuroendocrine neoplasms; definitions of neuroendocrine tumors, neuroendocrine carcinomas, and other rarer neuroendocrine neoplasms; and how to diagnose, grade, and stage neuroendocrine neoplasms. Particular attention is paid to current concepts and updates regarding high-grade neuroendocrine tumors, mixed adenoneuroendocrine carcinomas and mixed neuroendocrine-nonneuroendocrine neoplasms, updated tumor staging criteria, and novel insights into the genomic landscape of neuroendocrine neoplasms. Finally, examination of five real-world cases walks the reader through the approach to neuroendocrine neoplasms and explores many of the concepts introduced earlier in the chapter.

AimsDetermining the site of origin of a metastatic neuroendocrine tumour (NET) can be challenging and has important prognostic and therapeutic implications. An immunohistochemical (IHC) panel consisting of TTF1, CDX2, PAX8/PAX6 and Islet1 is often employed. However, there can be a significant IHC overlap among different primary sites. Herein, we sought to determine the utility of including Special AT-rich sequence binding protein-2 (SATB2) in the IHC panel that is used for determining the site of origin of a metastatic NET.MethodsParaffin tissue microarrays consisting of 137 primary NETs (26 lung, 22 jejunoileal, 8 appendix, 5 stomach, 4 duodenum, 17 rectum and 55 pancreas) were stained for SATB2, in addition to the well-described lineage-associated markers, such as TTF1, CDX2, PAX6 and Islet1. Additionally, a tissue microarray consisting of 21 metastatic NETs (1 lung, 1 stomach, 8 jejunoileal and 11 pancreas) was stained for TTF1, CDX2, SATB2 and Islet1. The results were recorded as no staining, weak staining and moderate to strong staining.ResultsAll appendiceal NETs and majority (88%) of the rectal NETs were positive for SATB2. All primary foregut NETs (stomach, pancreas, duodenum and lung) were negative for SATB2, except for one pulmonary NET with weak staining. However, among the metastatic tumours, 5 of 11 pancreatic NETs, 1 stomach NET, 1 lung NET and 2 of 8 jejunoileal NETs showed weak staining. Receiver operating characteristic analysis incorporating sensitivity and specificity data of IHC panel, considering moderate to strong staining as truly positive cases, showed that inclusion of SATB2 to the previously described NET IHC panel outperformed the panel without SATB2, raising the specificity for pancreaticoduodenal NETs from 81.2% to 100%, with a positive predictive value (PPV) of 100% and negative predictive value (NPV) of 82.22% (pConclusionsSATB2 stain is useful in differentiatingIslet1/PAX6 positive pancreatic and rectal NETs, as rectal NETs are typically moderately to strongly positive for SATB2 and pancreatic NETs are usually negative or weakly positive for SATB2. Moderate to strong staining for SATB2 is suggestive of an appendiceal or a rectal primary. SATB2 may complement the panel of CDX2, TTF1 and Islet1 in determining the site of origin of an NET in a metastatic setting.

Neuroendocrine neoplasms (NEN) most commonly arise in the gastroenteropancreatic system and lungs. The incidence of NEN is increasing globally, with improved diagnostic techniques identifying patients with early-stage disease. The number of approved therapies for the treatment of advanced disease has grown substantially in the past decade. The treatment algorithm for advanced NEN is evolving from one that is directed by primary site–specific classification to one that is directed by biologic classification, as evidenced by overlapping systemic treatments across the primary tumor sites. Commonalities in biologic characteristics across primary sites include functional status, differentiation status, grade, level of somatostatin receptor expression, and genetic alterations. In this review, we discuss current clinical evidence and available therapies for the treatment of advanced NEN and highlight the need for prospective trials in patients with well-differentiated, high-grade NEN. Implications for Practice This review raises awareness of the evolution of the treatment algorithm for advanced neuroendocrine neoplasms (NEN) from one that is directed by primary tumor site–specific classification to one that is directed by biologic classification. In addition, this review promotes understanding of the new pathologic category of well-differentiated G3 pancreatic neuroendocrine tumors and highlights the need for prospective trials in this patient population, for whom there is currently no standard of care. This review further provides a conceptual treatment schematic that categorizes the recommendations for systemic treatments for advanced disease by biologic classification, including the new and established categories of NEN.

Objectives Presacral neuroendocrine neoplasms (NENs) are rare entities that are found at the presacral space. We report our experience in the diagnosis, management, and outcomes of primary presacral NENs. Methods This was an institutional review board-approved retrospective review of medical records and surgical pathology specimens of patients with a diagnosis of NENs at Cedars-Sinai Medical Center between January 2000 and April 2016. Results Ten patients were identified. The median age at presentation was 38 years (range, 20-77 years), and 8 were women. One patient presented with carcinoid-like symptoms, 2 were diagnosed incidentally, and 7 presented with symptoms related to mass effect. The median size of the tumor was 7.0 cm (range, 3-12 cm). On pathologic review, 3 of 10 were low-grade and well-differentiated, 5 of 10 were intermediate-grade and well-differentiated, 2 of 10 were grade 3 and classified as high-grade and poorly differentiated neuroendocrine tumors. Seven cases were metastatic on presentation with lymph node, liver, lung, or skeletal metastasis. Seven of 8 cases were detectable using Octreoscan. Eight patients were treated with a somatostatin analog and 5 patients were treated surgically. Conclusions Presacral NENs are clinically similar to gastroenteropancreatic tumors. Octreoscan imaging and somatostatin analog therapies were frequently applied. Further biologic characterization of this rare subtype is needed.

Atypical spindle cell/pleomorphic lipomatous tumor (ASPLT) is a newly accepted entity that belongs to the group of low-grade adipocytic neoplasms. ASPLT commonly manifests a soft tissue mass in both upper and lower extremities but is extremely rare in the gastrointestinal tract. Here we report a case of a gastric ASPLT in a 59-year-old male, who presented for the evaluation of new onset of dysphagia. To our best knowledge, this is the first case report of ASPLT in the upper gastrointestinal tract.

There is debate regarding the definition and clinical significance of margin clearance in pancreatic ductal adenocarcinoma (PDA). A comprehensive archival analysis of surgical resection margins was performed to determine the effect on locoregional recurrence and survival, and the impact of adjuvant therapy in PDA.We identified 105 patients with resected PDA. Pancreatic, anterior, bile duct, and posterior surgical resection margins (PM; posterior surface, uncinate and vascular groove) were identified. Three pathologists reviewed all archival surgical specimens and recategorized each margin as tumor at ink/transected,0.5, 0.5-1,1-2, or2 mm from the inked surface. The impact of these and other clinical variables was assessed on local control, disease-free survival (DFS), and overall survival (OS).Among all margins, PM clearance up to 2 mm was prognostic of DFS (p = 0.01) and OS (p = 0.01). Dichotomizing the PM at 2 mm revealed it to be an independent predictor of local recurrence-free survival [hazard ratio HR] 0.20, 95% confidence interval [CI] 0.048-0.881, p = 0.033), DFS (HR 0.46, 95% CI 0.22-0.96, p = 0.03), and OS (HR 0.31, 95% CI 0.14-0.74, p = 0.008). A margin status of2 mm was also prognostic of OS in patients who received adjuvant chemotherapy (HR 0.31, 95% CI 0.11-0.89, p = 0.03), however this difference was mitigated in patients receiving adjuvant chemoradiotherapy (HR 0.40, 95% CI 0.10-1.58, p = 0.19).These data highlight the clinical significance of the PM and the lack of significance of other resection margins. Clearance in excess of 2 mm should be considered to improve long-term clinical outcomes. The use of adjuvant radiotherapy should be strongly considered in patients with PMs2 mm.

The transcriptional regulator Blimp1 plays crucial roles in controlling terminal differentiation in several lineages. In T cells, Blimp1 is expressed in both effector (Teff) and regulatory (Treg) cells, and mice with T cell-specific deletion of Blimp1 (Blimp1CKO mice) spontaneously develop severe intestinal inflammation, indicating a crucial role for Blimp1 in T cell homeostasis regulation. Blimp1 has been shown to function as a direct activator of the Il10 gene and although its requirement for IL10 expression has been demonstrated in both Treg and Teff cells under inflammatory conditions, the intrinsic requirement of Blimp1 for homeostatic maintenance of these T cell subsets had not been investigated. Using mice with Foxp3+ Treg-cell specific deletion of Blimp1 and other approaches, here we show that Foxp3+ Treg cell-intrinsic expression of Blimp1 is required to control Treg and Teff cells homeostasis but, unexpectedly, it is dispensable to prevent development of severe spontaneous intestinal inflammation. In addition, we show that Blimp1 controls common and unique aspects of Treg and Teff cell function by differentially regulating gene expression in these T cell subsets. These findings document previously unappreciated aspects of Blimp1’s role in T cell biology and shed light on the intricate mechanisms regulating Treg and Teff cell function.

Metastatic neuroendocrine neoplasms to the breast may show considerable morphologic overlap with primary mammary carcinomas, particularly those showing evidence of neuroendocrine differentiation, and may be misdiagnosed as such. Accurate distinction between these two entities is crucial for determination of appropriate clinical management. The histologic and immunohistochemical features of metastatic neuroendocrine neoplasms to the breast were studied and compared with the features of primary invasive mammary carcinomas with neuroendocrine differentiation, which served as controls. Of the metastatic neuroendocrine neoplasms, 15 were well-differentiated neuroendocrine tumors with carcinoid tumor-type morphology and 7 were poorly differentiated/high-grade neuroendocrine carcinomas with small-cell or large-cell neuroendocrine carcinoma morphology. The majority of the metastatic neoplasms originated in the lung and gastrointestinal tract. There were histologic similarities between metastatic neuroendocrine neoplasms and invasive mammary carcinomas with neuroendocrine differentiation, both of which exhibited neuroendocrine histologic features (nested and trabecular architecture, minimal tubular differentiation, and characteristic nuclear features). Only one case of the invasive mammary carcinomas with neuroendocrine differentiation was modified Bloom-Richardson grade 1 (largely due to minimal tubular differentiation on most such tumors), and the invasive mammary carcinomas with neuroendocrine differentiation were often associated with in situ carcinoma. Immunohistochemistry was helpful in distinguishing metastatic neuroendocrine neoplasms from invasive mammary carcinomas with neuroendocrine differentiation. Whereas the majority of invasive mammary carcinomas with neuroendocrine differentiation were positive for estrogen receptor and GATA3, metastatic neuroendocrine neoplasms were typically negative for estrogen receptor and GATA3, and metastatic well-differentiated neuroendocrine tumors often showed immunoreactivity for site-specific markers. Although the histologic and immunohistochemical features of a breast tumor may raise the suspicion of a metastatic neuroendocrine neoplasm, the pathologic findings should be interpreted in the context of the clinical history and imaging findings in order to establish an accurate diagnosis.

The number of molecular biomarkers to inform treatment decisions in patients with metastatic colorectal cancer (mCRC) continues to expand and with it the methodologies that can be employed to evaluate these biomarkers. Beyond standard diagnostic and prognostic biomarkers, such as those used for Lynch Syndrome, mutations in KRAS exon 2 are well established as predictive for lack of response to the anti–epidermal growth factor receptor therapies panitumumab and cetuximab. Recent studies have extended these findings by demonstrating that mutations in KRAS exons 3 and 4 and in NRAS exons 2, 3, and 4 (with all KRAS and NRAS mutations collectively referred to as RAS) are also predictive for treatment outcomes among patients with mCRC receiving panitumumab and cetuximab in combination with chemotherapy or as monotherapy. Consequently, evaluation of these additional loci has been incorporated into current clinical guidelines, and pathologists will need to develop testing procedures and algorithms to reliably and rapidly evaluate RAS status. With the increased number of mutations that must be examined to evaluate the status of RAS and other emerging biomarkers, next-generation sequencing technologies are likely to become increasingly important in mCRC testing. This review describes new considerations for pathologists that have arisen as a consequence of the incorporation of additional biomarker testing into clinical practice for mCRC.

Aims A wide spectrum of well-differentiated neuroendocrine proliferations (NEPs) are observed in inflammatory bowel disease (IBD), ranging from neuroendocrine tumours (NETs) to microscopic neuroendocrine cell clusters, best described as neuroendocrine cell micronests (NCMs). Finding NCMs in surveillance biopsies of IBD patients often poses a diagnostic conundrum. While such lesions may have been referred to as 'microcarcinoids' in the literature, it is unclear whether these represent early neoplasms. The study was undertaken to characterise NCMs and to differentiate NCMs from NETs. Methods and results Institutional surgical pathology archives were searched to identify cases of NEPs in IBD patients. Clinicopathological features were examined. NCMs were defined as scattered, indistinct neuroendocrine cell clusters without confluent growth or new stroma formation, located in the lamina propria and muscularis mucosae. NETs were defined as discrete, mass-forming lesions. Seventeen NEPs were identified, including eight NCMs and nine NETs. All NEPs were incidentally discovered. While NETs were commonly found in the rectum and appendix, NCMs were only noted in the rectosigmoid area. Unlike NETs, NCMs could not be measured as a discrete lesion as these clusters were non-confluent and scattered. None of the patients with NCMs developed NETs after a mean follow-up of 4.1 years (range = 0.5-21.0 years). None of the NETs showed NCMs in the background mucosa. Conclusions NCMs have distinct pathological features, are not associated with NETs in IBD patients and should not be misinterpreted as 'microcarcinoids'. Identification of NCMs in surveillance biopsies may not require further clinical work-up or invasive procedures usually performed for NETs.

Purpose: Hirschsprung-associated enterocolitis (HAEC) is the most frequent potentially life-threatening complication in children with Hirschsprung disease (HSCR) even after definitive corrective surgery. Mounting evidence suggests that intestinal microbiota likely contribute to the etiology of enterocolitis, so the aim of this study was to use a mouse model of post pull-through HAEC to compare the fecal bacterial communities of animals which developed HAEC to those free of enterocolitis. Methods: Ten Ednrb−/− and 8 wild type mice underwent the microsurgical pull-through surgery, and stool was collected at the time of surgery, and then either at 2 and 4 weeks after the operation, or when the mice developed enterocolitis. The mid-colon of all animals was collected, prepared and histologically graded for enterocolitis. Fecal DNA was isolated and bacterial 16S rRNA genes analyzed using Illumina sequencing. Results: Six Ednrb−/− mice developed HAEC with a mean enterocolitis score of 5.7, while the remaining 4 mutant and 8 WT mice remained free of enterocolitis by 4 weeks. The HAEC group had lower alpha diversity by Chao1 analysis compared with WT group, while the Ednrb−/− mice demonstrated distinct bacterial communities from WT mice on beta diversity analysis. The most striking finding was increased proportion of Akkermansia and reduced Bacteroidetes compared with the NO HAEC and WT groups, suggesting Akkermansia may contribute to development of enterocolitis while Bacteroidetes may be protective. Less abundant genera that were reduced in HAEC were Dysgonomas and Clostridium XIVa which may play a protective role. Conclusions: This is the first study to identify Akkermansia as potentially playing a role in HAEC, either as a pathobiont taxa contributing to pathogenesis of enterocolitis, or possibly a protective commensal taxa expanded in response to inflammation. These findings characterized the dynamic shifts in the gut microbial communities through the onset of post pull-through HAEC, and suggests that there may be identifiable bacterial community differences in HSCR patients that are high risk for developing HAEC.

We introduce and validate a new precision oncology framework for the systematic prioritization of drugs targeting mechanistic tumor dependencies in individual patients. Compounds are prioritized on the basis of their ability to invert the concerted activity of master regulator proteins that mechanistically regulate tumor cell state, as assessed from systematic drug perturbation assays. We validated the approach on a cohort of 212 gastroenteropancreatic neuroendocrine tumors (GEP-NETs), a rare malignancy originating in the pancreas and gastrointestinal tract. The analysis identified several master regulator proteins, including key regulators of neuroendocrine lineage progenitor state and immunoevasion, whose role as critical tumor dependencies was experimentally confirmed. Transcriptome analysis of GEP-NET-derived cells, perturbed with a library of 107 compounds, identified the HDAC class I inhibitor entinostat as a potent inhibitor of master regulator activity for 42% of metastatic GEP-NET patients, abrogating tumor growth in vivo. This approach may thus complement current efforts in precision oncology.

The classification of precursor lesions arising in the ampullary region and in the intrapancreatic biliary tract has recently evolved. It largely includes adenomas, papillary-tubular neoplasms of the ampulla and intrapancreatic bile duct, and flat dysplasia/biliary intraepithelial neoplasia (BiIIN). Ampullary adenomas (AA) arise from the duodenal surface of the ampulla. Exophytic/tumoural neoplastic precursor lesions occurring within the ampullary channel are designated intraampullary papillary-tubular neoplasms (IAPNs), and their counterparts within the bile ducts are called intraductal papillary neoplasms of the bile duct (IPNBs). While AAs are usually intestinal type, IAPNs and IPNBs have different phenotypes, including pancreatobiliary, intestinal, gastric, oncocytic, and mixed types. IAPNs and IPNBs have a high incidence of high grade dysplasia and associated invasive carcinoma. Non-invasive and minimally invasive papillary neoplasms have a much better prognosis than conventional carcinomas. BiIIN is presently categorized as BiIIN-1, BiIIN-2 and BiIIN-3. BiIIN can be difficult to distinguish from reactive atypia. The role of immunohistochemistry and FISH studies in the diagnostic evaluation of early neoplastic lesions is discussed.

Molecular analysis is revolutionizing our understanding of primary hepatobiliary tumours, and many gene products are being translated into immunohistochemical stains for routine use. Hepatocellular adenomas are divided into four genotypic subclasses using a panel of immunostains against liver-fatty acid binding protein, serum amyloid A, glutamine synthetase, and beta-catenin. Glutamine synthetase also differentiates adenomas from focal nodular hyperplasia. Glypican-3 and other novel markers are improving diagnostic accuracy for well-differentiated hepatocellular carcinoma, and hepatocyte paraffin antibody and arginase aid in identifying poorly differentiated hepatocellular carcinoma. Cholangiocarcinoma remains poorly understood, but a new generation of immunohistochemical markers is beginning to highlight important subtypes. Prognostic and predictive markers are under early investigation, with some as far in development as phase II clinical trials. Here we review new molecular-based immunohistochemical markers for all of these situations and others.

Potentially life-threatening enterocolitis is the most frequent complication in children with colonic aganglionosis (Hirschsprung disease, HSCR), and little is known about the mechanisms leading to enterocolitis. Splenic lymphopenia has been reported in the Endothelin Receptor B (Ednrb)-null mouse model of HSCR that develops enterocolitis. In this study, we sought to identify molecular mechanisms underlying this immune phenotype. We employed the Ednrb(-/-) mouse, and the knockout of its ligand, Edn3 (Edn3(-/-)). The major finding is that enterocolitis in the Ednrb(-/-) and Edn3(-/-) mice lead to thymic involution, splenic lymphopenia, and suppression of B lymphopoiesis as a consequence of colonic aganglionosis, not an intrinsic Edn3-Ednrb signaling defect directly affecting the lymphoid organs. We showed that adoptive transfer of Ednrb(-/-) marrow repopulated the RAG2-null mice marrow, thymus and spleen without development of enterocolitis. We identified the glucocorticoid corticosterone, as a potential mediator of the immune phenotype. This previously unrecognized pattern of immune abnormalities in mouse is nearly identical to lymphoid depletion in neonatal sepsis during severe physiological stress, suggesting that the mouse model used here could be also used for sepsis studies.

Calcifying fibrous tumor is a rare benign mass lesion characterized by bland spindle cells embedded in abundant collagenous matrix, interspersed dystrophic or psammomatous calcifications, and lymphoplasmacytic infiltrate. It shares several clinical and morphologic features with IgG4-related disease, a newly recognized fibroinflammatory disorder. Characteristic histologic features of IgG4-related lesions include dense fibrosis and abundant lymphoplasmacytic infiltrate, similar to calcifying fibrous tumor. They contain high numbers of IgG4-positive plasma cells in the tissue. Patients also often have elevated serum IgG4 levels. We report the case of a patient with an ileal calcifying fibrous tumor that contained 69 IgG4-positive plasma cells per high-power field and an IgG4-to-IgG ratio of 56% in lesional plasma cells. The patient's serum IgG4 level was 185 mg/dL, more than double the normal value. Altogether, these features suggest that calcifying fibrous tumor could be an unrecognized lesion of IgG4-related disease.

Background & Aims Genetic susceptibility loci for Crohn's disease (CD) are numerous, complex, and likely interact with undefined components of the environment. It has been a challenge to link the effects of particular loci to phenotypes of cells associated with pathogenesis of CD, such as Paneth cells. We investigated whether specific phenotypes of Paneth cells associated with particular genetic susceptibility loci can be used to define specific subtypes of CD. Methods We performed a retrospective analysis of 119 resection specimens collected from patients with CD at 2 separate medical centers. Paneth cell phenotypes were classified as normal or abnormal (with disordered, diminished, diffuse, or excluded granule phenotypes) based on lysozyme-positive secretory granule morphology. To uncover the molecular basis of the Paneth cell phenotypes, we developed methods to determine transcriptional profiles from whole-thickness and laser-capture microdissected, formalin-fixed, paraffin-embedded tissue sections. Results The proportion of abnormal Paneth cells was associated with the number of CD-associated NOD2 risk alleles. The cumulative number of NOD2 and ATG16L1 risk alleles had an additive effect on the proportion of abnormal Paneth cells. Unsupervised clustering analysis of demographic and Paneth cell data divided patients into 2 principal subgroups, defined by high and low proportions of abnormal Paneth cells. The disordered and diffuse abnormal Paneth cell phenotypes were associated with an altered transcriptional signature of immune system activation. We observed an inverse correlation between abnormal Paneth cells and presence of granuloma. In addition, high proportions of abnormal Paneth cells were associated with shorter time to disease recurrence after surgery. Conclusions Histologic analysis of Paneth cell phenotypes can be used to divide patients with CD into subgroups with distinct pathognomonic and clinical features.