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Background Congenital hepatic fibrosis (CHF) is a rare inherited form of ductal plate malformation associated with polycystic kidney disease. The diagnosis requires histopathologic confirmation, but can be challenging to distinguish from other undefined fibrocystic liver diseases. We aimed to describe the clinicopathologic features of congenital hepatic fibrosis (CHF), with comparisons to other entities that may clinically and/or histologically mimic CHF. Methods Nineteen cases that carried a clinical and/or histologic impression of CHF were identified at our institution, of which the histology was reassessed and reappraised into two categories: CHF (n=13) and mimics (n=6). The clinicopathologic features between the two groups were analyzed and compared. Results The CHF group was further sub-classified into those with clinical suspicion (CHF-c, n=8) and those as incidental histology findings (CHF-i, n=5). Patients of CHF-i were much older than CHF-c or mimics (P Conclusions Our study demonstrates classic histology triad of CHF despite a wide spectrum of clinical presentations. HPS is unexpectedly a clinical mimicker of CHF, which can be distinguished histologically.

ObjectivesAutoimmune metaplastic atrophic gastritis (AMAG) is an underrecognized entity, especially in its early stage. This study assessed whether the use of gastrin immunohistochemistry would increase sensitivity for diagnosing early AMAG.MethodsThree-hundred gastric biopsies were prospectively stained for gastrin by immunohistochemistry. Inclusion criteria included well-oriented gastric mucosa with mucus glands and minimal plasma cell infiltrate not suspected to represent pyloric metaplasia. Patient age, sex, designated location of biopsy, presence or absence of intestinal metaplasia, and clinical information were not criteria. Any case with absence of gastrin-positive endocrine cells reflexed to chromogranin immunohistochemistry. Maloriented biopsies or cases with current Helicobacter infection were excluded.ResultsThe 298-patient study cohort comprised 222 females (mean age, 47 years; range, 16-80 years) and 76 males (mean age, 49 years; range, 7-80 years). Biopsies were designated as “antral/antral nodules” (61%), and the rest were labeled “gastric/random stomach” (39%). Nine cases (3%) exhibited absence of gastrin-positive endocrine cells; one of those showed endocrine cell hyperplasia by chromogranin staining.ConclusionsPathologists should be aware of the histologic features of early AMAG and meticulously analyze tissue regardless of specimen labeling. Gastrin immunostain is a supplemental diagnostic tool when encountering inflamed antral-appearing specimens.

Management of anal dysplasia relies upon the accurate diagnosis of anal biopsy specimens. As institutions move towards subspecialty signout (SSSO), decisions must be made regarding whether to assign anal biopsies to the gastrointestinal (GI) or gynaecological (GYN) pathology service.We identified 200 archival tissue biopsies of anal mucosa and circulated them among three GI pathologists and three GYN pathologists. Each pathologist separately scored each biopsy as normal, atypical, low-grade squamous intra-epithelial lesion (LSIL) or high-grade squamous intra-epithelial lesion (HSIL). Every case that was called HSIL by at least one pathologist was stained with p16 immunostain and a 'gold standard' interpretation of whether or not a case represented HSIL was made. The GI pathologists agreed on 97 (49%) cases prior to consensus; the GYN pathologists agreed on 33 (17%). The sensitivities of the three GI pathologists in detecting HSIL against the 'gold standard' were 47, 100 and 21% and for the GYN pathologists the sensitivities were 74, 89 and 84%; the sensitivities of the GI and GYN consensus diagnoses were 74% each. The specificities of the three GI pathologists in detecting HSIL were 99, 90 and 100% and for the GYN pathologists the specificities were 99, 92 and 91%; the specificities of both the GI and GYN consensus diagnoses were 100%.A mild to moderate degree of interobserver variability exists in the diagnosis of anal dysplasia among pathologists. Our study indicates the utility of some form of consensus conference, as overall agreement among GI pathologists and among GYN pathologists improved following in-person consensus.

OBJECTIVES Human epidermal growth factor receptor 2 (HER2) is expressed in some gastric and gastroesophageal junction adenocarcinomas. There were two goals: assess the impact of specimen type on HER2 status and evaluate HER2 concordance with multiple specimens. METHODS All cases were evaluated by immunohistochemistry (IHC) for HER2 and interpreted using established criteria. Fluorescence in situ hybridization (FISH) was performed on a subset. RESULTS Of 460 specimens, 83.9% were IHC negative, 5.4% were equivocal, and 10.7% were IHC positive. Of those with FISH testing, 78.5% were FISH negative, and 21.5% were FISH positive. IHC-FISH concordance for biopsy specimens, resections, and metastases was 82%, 84%, and 86%, respectively. With one vs two vs three or more specimens, the HER2-positive rate increased from 10.5% to 18.1% to 24.1%, respectively. CONCLUSIONS HER2 testing may be performed on biopsy specimens with a relatively high concordance rate with resection specimens, and if multiple samples are analyzed from a single patient, the HER2-positive rate increases over twofold.

Colonic leiomyomas are relatively common lesions discovered incidentally during colonoscopy, particularly in the distal sigmoid colon and rectum. The classic histologic appearance of colonic leiomyomas are well-circumscribed lesions that arise from the muscularis mucosae and occupy the submucosa. They are composed of well-differentiated smooth muscle cells that are spindled with cigar-shaped nuclei and abundant eosinophilic cytoplasm. Traditionally, leiomyomas stain positively for markers of smooth muscle differentiation, such as desmin and smooth muscle actin. Herein, we describe a case of a 53-year-old woman with an incidentally discovered colon polyp that revealed epithelioid cells within a chondroid-type matrix, with ERG and smooth muscle actin expression. To our knowledge, this is the first case of an epithelioid leiomyoma of the colon with chondroid differentiation described in the literature. We describe the unique morphologic and immunohistochemical properties of this lesion and we highlight the potential diagnostic pitfalls that may be encountered during the work-up of this entity.

Reactivation of latent varicella zoster virus (VZV) may be limited to a dermatome or involve multiple organs, including the gastrointestinal tract. Although gastrointestinal manifestations of disseminated zoster have been likened to those of herpes simplex virus (HSV), histologic features of VZV-related injury to the tubular gut are not well-documented. We performed this study to describe the clinicopathologic features of VZV-related gastrointestinal injury. We identified 6 such patients with VZV infection. All involved the upper gastrointestinal tract, affecting the esophagus (n=3), stomach (n=2), or both (n=1). All patients were immunocompromised adults with hematologic malignancies (n=5) or a heart transplant (n=1); 3 with hematologic malignancies had received stem cell transplants. Five patients had cutaneous and gastrointestinal zoster; 1 had gastrointestinal disease alone. When compared with 14 HSV-related esophagitis controls, there were several notable differences. VZV caused hemorrhagic ulcers with nodularity or erythema, whereas HSV produced round, shallow ulcers on a background of nearly normal mucosa (P=0.01). VZV-related ulcers featured fibrin-rich, pauci-inflammatory exudates compared with the macrophage-rich exudates of HSV (P=0.003). The cytopathic changes of VZV were present at all levels of the squamous epithelium, especially in a peripapillary distribution. In contrast, HSV inclusions were located in the superficial layers (P=0.003) and detached keratinocytes. Unlike HSV, VZV involved the stomach, producing hemorrhage accompanied by striking apoptosis in the deep glands. We conclude that VZV produces unique patterns of gastrointestinal injury that facilitate its diagnosis. Recognition of gastrointestinal VZV infection is important because it heralds potentially life-threatening disseminated disease.

Subspecialty sign-out is increasingly common in academic medical centers as well as some community practices. Reducing interobserver variability in anatomic pathology is desirable so that clinicians can select the appropriate therapy. Many departments that elect subspecialty sign-out do so with the assumption that it will improve diagnostic accuracy and interobserver variability-but does it? The literature is mixed.

Background Histoplasma capsulatum is the most common endemic mycosis in the United States and frequently presents as an opportunistic infection in immunocompromised hosts. Though liver involvement is common in disseminated histoplasmosis, primary gastrointestinal histoplasmosis of the liver in absence of lung involvement is rare. Similarly, cholestatic granulomatous hepatitis in liver histoplasmosis is rarely seen. Case presentation We present a rare case of primary gastrointestinal histoplasmosis manifesting with acute granulomatous hepatitis and cholestasis in a 48-year-old female with psoriatic arthritis, receiving methotrexate and infliximab. The epidemiology, risk factors, clinical presentation, diagnosis, and treatment of histoplasmosis is discussed. Furthermore, we review the published cases of biopsy-proven disseminated histoplasmosis with cholestatic jaundice to highlight histoplasmosis involvement in the liver. Conclusion Histoplasmosis should be considered in immunosuppressed patients with fever, chills, abdominal pain and cholestasis with progressive jaundice, particularly in subjects without evidence of biliary obstruction. Future studies are needed to accurately assess the risk of this fungal infection, specifically in patients on immunomodulatory therapy for autoimmune disease.

Intrahepatic cholangiocarcinoma (iCCA) is a primary liver cancer epidemiologically linked with liver injury, which has poorly understood incipient stages and lacks early diagnostics and effective therapies. While iCCA is conventionally thought to arise from the biliary tract, studies have suggested that both hepatocytes and biliary cells (cholangiocytes) may give rise to iCCA. Consistent with the plasticity of these cell lineages, primary liver carcinomas exhibit a phenotypic range from hepatocellular carcinoma (HCC) to iCCA, with intermediates along this spectrum. Here, we generated mouse models to examine the consequence of targeting mutant Kras and Tp53, common alterations in human iCCA, to different adult liver cell types. Selective induction of these mutations in the SOX9+ population, predominantly consisting of mature cholangiocytes, resulted in iCCA emerging from premalignant biliary intraepithelial neoplasia (BilIN). In contrast, adult hepatocytes were relatively refractory to these mutations and formed rare HCC. In this context, injury accelerated hepatocyte-derived tumorigenesis and promoted a phenotypic switch to iCCA. BilIN precursor lesions were absent in the hepatocyte-derived iCCA models, pointing toward distinct and direct emergence of a malignant cholangiocytic phenotype from injured, oncogenically primed hepatocytes. Tp53 loss enhanced the reprogramming of hepatocytes to cholangiocytes, which may represent a mechanism facilitating formation of hepatocyte-derived iCCA. Overall, our work shows iCCA driven by Kras and Tp53 may originate from both mature cholangiocytes and hepatocytes, and factors such as chronic liver injury and underlying genetic mutations determine the path of progression and resulting cancer phenotype. Significance: The histopathogenesis of biliary tract cancer, driven by Tp53 and Kras mutations, can be differentially impacted by the cell of origin within the mature liver as well by major epidemiologic risk factors. Cancer Res; 78(16); 4445–51. ©2018 AACR.

Insulin-like growth factor-II messenger RNA-binding protein-3 (IMP3), is an oncofetal protein whose aberrant expression has previously been detected in multiple malignant neoplasms. Pulmonary neuroendocrine carcinomas demonstrate increased expression compared with pulmonary carcinoid tumors, but this relationship has not been studied in gastrointestinal neuroendocrine tumors (GINETs). This study examined IMP3 expression in GINETs, with a focus on correlation with established grading criteria. Fifty-four GINETs were immunohistochemically studied using a monoclonal antibody against IMP3. Using established World Health Organization criteria, the cases were stratified by grade and included 31 grade 1 neuroendocrine tumors (G1 GINETs), 15 grade 2 neuroendocrine tumors (G2 GINETs), and 8 neuroendocrine carcinomas (GINECs). The majority (51/54, 94.4%) of GINETs demonstrated IMP3 staining. Thirty cases (55.6%) showed IMP3 cytoplasmic/membranous staining in 60% or greater of tumor cells, with moderate to strong staining in nearly all of these cases (29/30; 96.7%). Of the remaining 24 cases, 3 cases showed no staining, whereas 17 (81%) demonstrated weak staining. When stratified by grade, there was no statistically significant difference in IMP3 staining among the 3 grades of GINETs; of the G1 GINETs, 14 (45.2%) demonstrated staining in at least 60% of tumor cells, compared with 10 (66.7%) G2 GINETs and 6 (75%) GINECs. Hindgut neoplasms of any grade were the most likely to show significant IMP3 staining. Unlike what has been demonstrated in neuroendocrine neoplasms in the lungs, GINETs appear to have a consistent IMP3 expression profile among all tumors grades, which may be reflective of their unique tumor biology.

Context: Liver cancers (including hepatocellular carcinoma [HCC] and cholangiocarcinoma) are the fifth most common cause of cancer death. The most powerful independent histologic predictor of overall survival after transplantation for HCC is the presence of microscopic vascular invasion (VI). Aims: Given that VI is known to have somewhat high interobserver variability in both HCC and other tumors, we hypothesized that pathologists with special interest and training in liver pathology would be more likely to identify and report VI in HCC than would general surgical pathologists. Settings and Design: We searched our departmental surgical pathology archives for transplant hepatectomies performed for HCC. Subjects and Methods: We identified 143 such cases with available sign-out reports and hematoxylin and eosin-stained slides. Statistical Analysis Used: Kappa results (level of agreement) were calculated. Results: Before surgical pathology subspecialty sign-out (SSSO) implementation, 49 of 88 HCC cases were reported as negative for VI; on rereview, 20 of these had VI. After SSSO implementation, 39 of 55 cases were reported as negative for VI; on our review, 8 of these had VI. Kappa (agreement) between general SO and subspecialty rereview was 0.562 (95% confidence interval [CI] = 0.411–0.714) “weak agreement.” Kappa (agreement) between SSSO and rereview by select liver pathologists was 0.693 (95% CI = 0.505–0.880) “moderate agreement.” Conclusions: Our study is one of only a few so far that have suggested improved accuracy of certain parameters under SSSO.

Microscopic colitis (MC) includes lymphocytic colitis (LC) and collagenous colitis (CC). Microscopic changes are required to establish these diagnoses. While criteria exist, interobserver variability has been reported previously. This has not been evaluated in the context of subspecialty signout (SSSO) or a consensus conference. We identified 133 colon biopsies diagnosed as LC, CC, MC, or normal but with mild changes insufficient for MC. All predated the introduction of SSSO at our institution. They were independently reviewed by three gastrointestinal (GI) pathologists. Cases lacking independent consensus were reviewed by the same pathologists in consensus conference to establish a final diagnosis. Individual diagnoses were compared with the consensus diagnoses, and consensus diagnoses were compared with original diagnoses made by GI and non-GI pathologists. Consensus diagnoses were normal (n = 34), LC (n = 57), and CC (n = 42). “Normal” was the diagnosis most commonly agreed upon independently (27/34 cases, P = 0.0073 versus LC, P = 0.0172 versus CC). The reviewing pathologists independently agreed with 80%, 80%, and 94% of consensus diagnoses (κ = 0.70, 0.69, and 0.91). The group consensus agreed with the diagnoses in 49 of 58 (84%) cases originally signed out by non-GI pathologists (κ = 0.77) and in 44 of 57 (77%) cases originally signed out by GI pathologists (κ = 0.63). Good interobserver agreement exists for MC, though whether GI subspecialty training improves agreement remains unclear. Group consensus may aid in diagnosis of difficult/borderline MC cases.

Vascular abnormalities and lesions of the small bowel and colon are rare. A florid vascular proliferation (FVP) associated with colon obstruction and intussusception has been described and can mimic malignant vascular tumors such as angiosarcoma. In this article, we report a case of colonic FVP associated with colon obstruction, a case of small bowel FVP associated with a Meckel’s diverticulum, and a case of small bowel FVP with intussusception. All cases occurred in older adults (mean 73 years of age, range 62-80 years of age). FVP grossly appeared as a mass-like lesion in one small bowel case, while the other cases did not demonstrate a grossly identifiable mass. Histologically, all cases demonstrated a transmural vascular proliferation with plump endothelial cells. No significant cytologic atypia was seen, and mitotic figures were rare. No recurrence was seen in all cases with an average follow-up of 22 months. It is important to be aware of this entity as it appears to be a nonneoplastic reactive process, unlike some of its histologic mimics.

The Cancer Genome Atlas Research Network recently classified gastric adenocarcinoma into 4 molecular subtypes: Epstein-Barr virus-positive tumors, microsatellite-unstable tumors, tumors with chromosomal instability, and genomically stable tumors. We theorized that immunohistochemistry might be useful in similar categorization and that that HER2 expression might relate to subtype. We stained 104 gastric adenocarcinomas for MLH1, p53, and EBER in situ hybridization. We grouped them based on staining pattern and compared the groups. Cases were categorized as follows: group 1 (EBER positive), 7 cases (7%); group 2 (MLH1 deficient), 17 cases (16%); group 3 (aberrant p53 staining, EBER negative, retained MLH1), 40 cases (38%); group 4 (unremarkable staining), 40 cases (38%). This distribution was comparable to that found by the Research Network after accounting for the TP53 mutation rate in the chromosomal instability group. Group 1 patients had significantly longer follow-up times (median, 70 months versus 13 months for other groups; P = .0324). No group 2 cases overexpressed HER2. In group 3, 3 of 40 cases were HER2 immunohistochemistry positive, but 7 of 27 were HER2 positive by fluorescence in situ hybridization. Staining offers an efficient, reasonably accurate alternative for molecular subtyping of gastric adenocarcinoma, although some cases with chromosomal instability cannot be identified. These findings have potential prognostic and therapeutic implications.

Objectives Indications for cholecystectomy have changed dramatically over the past three decades. Cystoisospora belli has been reported in cholecystectomy specimens of immunocompetent patients. The present study was designed to determine the prevalence and clinical association of C belli in the gallbladder. Methods The study included retrospective review of cholecystectomy specimens (n = 401) removed for various indications, and a prospective cohort of cholecystectomy specimens (n = 22) entirely submitted for histologic evaluation. Correlations of presence of C belli with age, sex, clinical indication, and abnormalities of preoperative laboratory values were assessed by Fisher exact test. Results C belli was identified in 39/401 (9.7%) of the retrospective cohort, and 6/22 (27.3%) of the entirely submitted specimens. The presence of C belli showed no correlation with age, sex, clinical indication, or laboratory abnormalities. Conclusions C belli resides in a latent state in the gallbladder and may be best considered a commensal organism.

ObjectiveHere, we evaluate the contribution of AT-rich interaction domain-containing protein 1A (ARID1A), the most frequently mutated member of the SWItch/sucrose non-fermentable (SWI/SNF) complex, in pancreatic homeostasis and pancreatic ductal adenocarcinoma (PDAC) pathogenesis using mouse models.DesignMice with a targeted deletion of Arid1a in the pancreas by itself and in the context of two common genetic alterations in PDAC, Kras and p53, were followed longitudinally. Pancreases were examined and analysed for proliferation, response to injury and tumourigenesis. Cancer cell lines derived from these models were analysed for clonogenic, migratory, invasive and transcriptomic changes.ResultsArid1a deletion in the pancreas results in progressive acinar-to-ductal metaplasia (ADM), loss of acinar mass, diminished acinar regeneration in response to injury and ductal cell expansion. Mutant Kras cooperates with homozygous deletion of Arid1a, leading to intraductal papillary mucinous neoplasm (IPMN). Arid1a loss in the context of mutant Kras and p53 leads to shorter tumour latency, with the resulting tumours being poorly differentiated. Cancer cell lines derived from Arid1a-mutant tumours are more mesenchymal, migratory, invasive and capable of anchorage-independent growth; gene expression analysis showed activation of epithelial-mesenchymal transition (EMT) and stem cell identity pathways that are partially dependent on Arid1a loss for dysregulation.ConclusionsARID1A plays a key role in pancreatic acinar homeostasis and response to injury. Furthermore, ARID1A restrains oncogenic KRAS-driven formation of premalignant proliferative IPMN. Arid1a-deficient PDACs are poorly differentiated and have mesenchymal features conferring migratory/invasive and stem-like properties.

SummaryMutations in p53 and RAS potently cooperate in oncogenic transformation, and correspondingly, these genetic alterations frequently coexist in pancreatic ductal adenocarcinoma (PDA) and other human cancers. Previously, we identified a set of genes synergistically activated by combined RAS and p53 mutations as frequent downstream mediators of tumorigenesis. Here, we show that the synergistically activated gene Plac8 is critical for pancreatic cancer growth. Silencing of Plac8 in cell lines suppresses tumor formation by blocking autophagy, a process essential for maintaining metabolic homeostasis in PDA, and genetic inactivation in an engineered mouse model inhibits PDA progression. We show that Plac8 is a critical regulator of the autophagic machinery, localizing to the lysosomal compartment and facilitating lysosome-autophagosome fusion. Plac8 thus provides a mechanistic link between primary oncogenic mutations and the induction of autophagy, a central mechanism of metabolic reprogramming, during PDA progression.

Objectives Biopsies of liver lesions frequently have two goals: confirm malignancy and determine the site of origin. We frequently encounter liver biopsies in patients with pancreatic mass (PM). Given the lack of a specific marker for pancreatic adenocarcinoma, a broad panel of immunohistochemical (IHC) stains is frequently done. In this study, we evaluated the usefulness of IHC staining in the setting of a liver biopsy in the presence of PM. Methods Between 2011 and 2017, 85 cases of liver biopsies or segmental resections with a diagnosis of adenocarcinoma in the presence of PM were retrieved from our archives. Clinical history of other malignancies, any other lesions detected by imaging studies, CA19-9 levels, and reevaluation of the available H&E and IHC slides were performed. Results The patients were divided into four groups: 74.1% with isolated PM on imaging and no previous history of any malignancy, 12.9% with PM on imaging with previous history-proven adenocarcinoma of the pancreas, 7.0% with PM in association with another lesion shown by imaging studies in other organs, and 5 (5.8%) PM on imaging in association with previous history of cancer somewhere else other than pancreas. At least two IHC stains were performed for each case. CK7 was ordered in all the cases and was positive in 100%; CK20 was positive in 35.8%. Interestingly, TTF-1 was positive in only one case, in the absence of discrete lung mass; the patient was treated for pancreatic adenocarcinoma. Conclusion We suggest that in the presence of PM, with liver metastasis of adenocarcinoma morphology on H&E, the metastasis is from the pancreas or upper gastrointestinal primarily and no need for further stains. Although performing IHC is useful sometimes, it should be ordered wisely; this practice will lower costs and result in higher quality care, with more effective use of the lab resources and personnel.

Clinical laboratory testing for human epidermal growth factor receptor-2 (HER2) in patients with newly diagnosed breast and gastric cancer is critically important for therapeutic decisions about adjuvant treatment. The HER2 pathway is a major molecular driver of disease progression in a subset of these solid tumors and the results of HER2 testing determine which patients are likely to respond to an expanding variety of therapies that target this important biologic pathway. Given the significant clinical impact of these test results on patient management and adjuvant treatment decisions, standardization of the assay for HER2 and assured reliability of these results are critical. We review highlights of the clinical rationale that underlies HER2 testing for both breast and gastric carcinomas, and describe some of the challenges associated with ensuring accurate test results.

Background Liver cancer, of which hepatocellular carcinoma (HCC) is by far the most common type, is the second most deadly cancer (746,000 deaths in 2012). Currently, the only curative treatment for HCC is surgery to remove the malignancy (resection) or to remove the entire diseased liver followed by transplantation of healthy liver tissue. Given the shortage of healthy livers, it is crucial to provide transplants to patients that have the best chance of long-term survival. Currently, transplantation is determined via the Milan criteria—patients within Milan (single tumor

Eosinophilic esophagitis (EE), initially described in children, is now recognized in adults. The prevalence of EE in adults is largely unknown. Our goals were to determine the prevalence of EE in an adult population undergoing esophagogastroduodenoscopy with biopsy as originally reported and on retrospective review, the rate at which EE was present before this diagnosis was readily appreciated, and whether the prevalence of EE has changed over time. We reviewed esophageal biopsy specimens from 1992 to 2004. If there were more than 15 eosinophils per high-power field and confirmatory clinical information was available, EE was diagnosed. The initial (prereview) prevalence was 1.3%; prevalence on retrospective review was 1.7%. Prevalence was higher in later years (3.8%) compared with early years (0.3%). The demographics of our patients with EE are generally similar to what has been reported. Our results suggest the prevalence of EE is increasing and that pathologists provide accurate diagnoses in the face of changing criteria and significance.

Adenocarcinomas of the stomach and gastroesophageal junction represent a major cause of cancer morbidity and mortality world wide. Complete surgical resection is the mainstay of treatment for nonmetastatic disease; however, many patients are not diagnosed until their disease is either locally advanced or metastatic and therefore unresectable. Clearly, there is an unmet clinical need for new therapeutic strategies, treatment options, and novel therapeutic targets. In a recent trial (Trastuzumab for GAstric cancer), patients assigned to the trastuzumab treatment protocol showed an improved overall survival over those not receiving treatment. Trastuzumab has recently been approved for treatment of advanced gastric and gastroesophageal junction cancers. Pathologists and diagnostic laboratories must be prepared for this new category of specimens requiring human epidermal growth factor receptor 2 testing, and have an awareness of the interpretive differences between breast and gastric cancers.

Lynch syndrome, originally described in 1913 and previously known as hereditary nonpolyposis colorectal carcinoma syndrome, is the most common hereditary cancer syndrome. This syndrome is classically due to germline mutations in the mismatch repair genes MLH1, MSH2, MSH6, or PMS2. The cancer risk for patients with Lynch syndrome is not limited to the colorectum; women with Lynch syndrome are at risk for endometrial cancer, and Lynch patients of both genders are at risk for other cancers as well. There are cases of cancers in families that meet the clinical criteria (Amsterdam and Bethesda criteria) for Lynch syndrome but do not have a mutation in the one of the four classic mismatch repair genes. For some time, there has been speculation that other mutations or mechanisms were responsible for a subset of Lynch syndrome patients; much research has gone into identifying those alternative mutations and mechanisms. Recently, EPCAM deletion, CHEK2 mutations, and germline MLH1 hypermethylation have been identified as alternative mutations that cause Lynch syndrome in mismatch repair-negative patients. This article reviews these novel mechanisms and mutations, their clinical significance, and the pathogenesis of these Lynch causing mutations.

Gastric adenocarcinoma is a major cause of morbidity and mortality in the world with median overall survival being less than a year [1-4]. Advanced gastric adenocarcinoma is associated with a dismal prognosis, and increasing survival time, even by a few months, can be significant in this patient population [3,5,6]. Recently there was a major breakthrough in the treatment of gastric cancer, which arose by studying a therapy currently used for treatment of another solid tumor, HER2 positive breast carcinoma. Trastuzumab, a monoclonal antibody that targets the extracellular domain of the HER2 receptor, has become standard first-line treatment in this classification of breast carcinomas [7-10]. A recent clinical trial (ToGA) using trastuzumab in combination with chemotherapy versus chemotherapy alone for treatment of HER2positive advanced gastric or gastro-esophageal junction cancer showed an increase in overall survival in advanced (inoperable locally advanced, recurrent, or metastatic) gastric cancer treated with chemotherapy plus trastuzumab versus chemotherapy alone [1]. This was the first time a biological therapeutic was proven to increase survival in gastric cancer. Critical to the ToGA trial was determining which patients would be eligible for randomization i.e. which patients had tumors that over-expressed HER2. Therefore, not only was trastuzumab shown to prolong survival in patients with advanced gastric cancer, but a protocol was proposed for HER2 testing in gastric cancer in a corollary study [11]. HER2 interpretation in gastric cancer is similar to, but slightly different than interpretation in breast cancer. Hofmann put forth an initial proposal, which was subsequently validated with minor clarifications added by Ruschoff [11,12]. The modifications in gastric cancer HER2 interpretation are related to heterogeneity (percentage of cells positive and different criteria in biopsies versus resections) and physiology (pattern of staining basolateral/lateral versus complete circumferential staining). The ToGA study established trastuzumab as a viable treatment option in advanced gastric cancer and led to approval by the Food and Drug Administration (FDA) and the European Union for its use in combination with chemotherapy in that setting [13,14]. The most recent National Comprehensive Cancer Network (NCCN) Guidelines recommend trastuzumab with chemotherapy for patients with advanced or metastatic cancer, if the tumor is HER2 positive as confirmed by immunohistochemistry (IHC 3+) or fluorescence in situ hybridization (FISH score ≥ 2 for IHC 2+ tumors).

There are multiple hereditary and non-hereditary polyposis syndromes that were originally categorized as adenomatous or hamartomatous. More recently, serrated polyps and their syndromes have been defined. Nearly all of these syndromes have a risk of colorectal cancer in the individuals and affected family members. Most of these syndromes are associated with extracolonic manifestations, including extracolonic tumors. The major clinical features, genetic mechanisms, and clinical management of Familial Adenomatous Polyposis (FAP), Peutz-Jeghers Syndrome (PJS), Juvenile Polyposis Syndrome (JPS), PTEN Hamartoma Syndrome (PTHS), and the more recently described syndromes MUTYH-Associated Polyposis, Hereditary Mixed Polyposis Syndrome, Serrated Polyposis Syndrome, and Polymerase Proofreading Associated Polyposis are summarized in this article.

These multimedia modules have been developed to teach senior medical students on their surgical pathology elective the basic microscopic features of common surgical pathology diagnoses. The modules include normal histology and pathology organized into the following organ systems: breast, gastrointestinal, genitourinary, gynecologic, liver, and lung. The first component to this teaching set is a review of normal histology which may serve as a comparison for the histopathology component. A low- and high-power micrograph of each organ is provided. The student is tested with a quiz of micrographs of normal histology where they must identify the organ. Next, students review commonly encountered biopsies in each organ system. Under each diagnosis is listed the definition, etiology, symptoms/indications for biopsy, gross features, microscopic features, and a differential diagnosis. Radiologic features and pertinent additional stains are noted when appropriate. The goal of the surgical pathology rotation at this institution is to allow students to function as junior house officers, actively participating in previewing and sign-out. These teaching modules will provide basic clinical and microscopic descriptions to help the student preview and diagnose biopsy specimens on their own. The clinical implications of certain diagnoses as they pertain to aggressive management in neoplastic disease will also be mentioned. The modules are designed so students can easily navigate between slides, diagnoses, and differentials. Each image is provided with arrows and labels (which may be hidden) to guide the eye of the learner to recognize the patterns of each diagnosis. After completing a module, students will solidify their knowledge with a quiz. We plan to monitor the effectiveness of this assessment by having students take the quiz at the start and end of the rotation to compare the change in their score. These modules will provide an organized foundation on which the student may build his or her knowledge during slide review with senior residents or staff pathologists.

The anatomic pathology discipline is slowly moving toward a digital workflow, where pathologists will evaluate whole-slide images on a computer monitor rather than glass slides through a microscope. One of the driving factors in this workflow is computer-assisted scoring, which depends on ap- propriate selection of regions of interest. With advances in tissue pattern recognition techniques, a more precise region of the tissue can be evaluated, no longer bound by the pathologist's patience in manually outlining target tissue areas. Pathologists use entire tissues from which to determine a score in a region of interest when making manual immunohistochemistry assess- ments. Tissue pattern recognition theoretically offers this same advantage; however, error rates exist in any tissue pattern rec- ognition program, and these error rates contribute to errors in the overall score. To provide a real-world example of tissue pattern recognition, 11 HER2-stained upper gastrointestinal malignancies with high heterogeneity were evaluated. HER2 scoring of gastric cancer was chosen due to its increasing im- portance in gastrointestinal disease. A method is introduced for quantifying the error rates of tissue pattern recognition. The trade-off between fully sampling tumor with a given tissue pat- tern recognition error rate versus randomly sampling a limited number of fields of view with higher target accuracy was mod- eled with a Monte-Carlo simulation. Under most scenarios, stereological methods of sampling-limited fields of view out- performed whole-slide tissue pattern recognition approaches for accurate immunohistochemistry analysis. The importance of educating pathologists in the use of statistical sampling is dis- cussed, along with the emerging role of hybrid whole-tissue imaging and stereological approaches. BACKGROUND Despite recent improvements in surgical techniques and chemotherapy treatments, locally advanced/meta- static gastroesophageal junction (GEJ) and gastric cancer (GC) are still associated with poor clinical outcome. Re- sults from the Trastuzumab for Gastric Cancer trial demonstrated that trastuzumab, a monoclonal antibody directed against the extracellular domain of HER2, can enhance the efficacy of cytotoxic chemotherapy in pa- tients with advanced gastric and gastroesophageal can- cers. The pathologic analysis for HER2 in GC by immunohistochemistry (IHC) is currently performed with either manual scoring following the Hofmann-modified scoring criterion for GC 1 or the use of the Food and Drug Administration (FDA)-cleared HER2 algorithms de- signed for breast cancer. 2,3 To date, there are no image analysis algorithms that have been developed or have been approved specifically for the evaluation of HER2 protein overexpression in GC. Tumor heterogeneity presents a difficult problem in

Adenocarcinomas of the esophagus and stomach constitute a substantial number of cancer cases worldwide. Most patients in the United States are diagnosed at an advanced or metastatic stage and, therefore, the prognoses have been poor. New treatments are needed to augment standard surgical and medical management. Recent studies have shown that a subset of esophageal and gastric adenocarcinomas overexpress the HER2 protein, similar to the overexpression seen in breast cancer. Because trastuzumab, a monoclonal antibody to the HER2 receptor, has been used with success in primary and HER2 positive metastatic breast cancers, the phase III ToGA trial was designed to assess the impact of trastuzumab in patients with HER2 positive gastric cancers. They have reported an increase in overall survival time for patients treated with chemotherapy and trastuzumab compared to those treated with chemotherapy alone. They have reported an increase in overall survival time for patients treated with chemotherapy and trastuzumab compared to those treated with chemotherapy alone. This means that accurate HER2 testing in gastric and esophageal carcinomas is necessary. While the breast cancer scoring system can be used to determine HER2 status in most cases, modifications are necessary to accommodate the heterogeneity and incomplete membrane staining that are observed more frequently in gastric cancers. An understanding of the scoring modifications is required for proper stratification of gastric cancer patients for treatment.

A) Pancreatic ductal adenocarcinoma (PDA) depends on a marked reprogramming of metabolic pathways, including the acquisition of autophagy dependence, for survival and growth. How common mutations in PDA cause autophagy dependence as well as the timing of autophagy activation in the course of cancer progression, have not been established. Here we show how Plac8, a gene synergistically up-regulated in response to the common cooperating oncogenic mutations found in PDA (RAS activation and functional loss of p53), is critical to the growth of PDA by sustaining autophagy via facititating autophagosome-lysosome fusion. Furthermore, we delineate that Kras and p53 mutations cooperate to induce autophagic flux. B) To establish Plac8’s role in PDA growth and autophagy we use murine cell lines and human PDA cell lines to determine 1) the lysosomal localization of Plac8, 2) its role in regulating autophagy using both loss of function and gain of function approaches, 3) the impact on lysosomal biology, and 4) the relationship between Plac8 and other genetic pathways governing autophagy. Using genetically engineered models of PDA we determine the timing of autophagy activation in PDA progression and the impact of Plac8 mutation. C) We identify Plac8 as a novel regulator of autophagosome-lysosome fusion required for PDA growth, thus providing a mechanistic link between oncogenic mutations and the activation of autophagy in cancer. Plac8 expression is required for growth of human PDA cells as xenografts in mice, as well as activation of autophagy. We find that concurrent mutation of KRAS and p53 is critical for maximal induction of autophagy in vitro. Correspondingly, using genetically engineered mouse models of PDA (Pdx1-Cre; LSL-KrasG12D; p53L/+), in which loss of p53 function occurs in a step-wise manner relying on the spontaneous loss of a heterozygous WT p53 allele, we see a step-wise incremental increase in LC3 puncta in vivo with each histological stage through the course of PDA progression. Thus, we find that the cooperative effects of KRAS and p53 drive activation of autophagy rather than either mutation alone. The overall survival of a Pdx1-Cre; LSL-KrasG12D; p53L/+; Plac8null murine cohort (OS 27.9 wks) was significantly longer than a Pdx1-Cre; LSL-KrasG12D; p53L/+; Plac8wt cohort (OS 17.0 wks, p=0.0006) demonstrating in vivo that genetic inactivation of Plac8 impedes cancer progression and resulting death. Our data suggest that the role of Plac8 in facilitating autophagy is critical to cancer, as the requirement of Plac8 for both tumorigenicity and autophagy can be compensated by over-expression of Atg12, a gene critical for autophagosome formation or by constitutively activated Rab7, a gene encoding a GTP-binding protein stimulating autophagosome-lysosome fusion. D) We conclude that Plac8 may offer a potential therapeutic window and point of intervention, as Plac8 mutation in the engineered PDA model inhibits cancer progression and significantly improves survival while having a minimal impact on the overall fitness of the animals. In fact, Plac8, and regulation of autophagosome-lysosome fusion, has specific relevance to regulation of autophagy during malignant cell transformation as Plac8 and the processes it regulates, appear to be largely dispensable to many normal physiologic processes. This abstract is also presented as Poster B36. Citation Format: Vijaya Balakrishnan, Kinsey Conan, Michael O'Dell, Jing Li Huang, Laurel Newman, Christa Whitney-Miller, Hartmut Land, Aram Hezel. Plac8 links oncogenic mutations to regulation of autophagy and is critical to pancreatic cancer progression. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr PR09.

The current integrated model of medical student education has the potential to de-emphasize pathology as a crucial discipline. With a move away from traditional lecture-based courses in pathology, an investigation of novel teaching methodologies for pathology education is necessary. To this point we developed a pathology-focused team-based learning (TBL) exercise to supplement clinically based lectures provided by clinicians in the …