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Objectives Primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) can be difficult to distinguish in end-stage liver disease. Previous studies have shown that immunoglobulin G (IgG) and immunoglobulin M (IgM) immunostaining can differentiate AIH from PBC in needle core biopsy specimens, and we seek to extend these data to cirrhotic liver explants, in which the histology of AIH or PBC may be indiscernible. Methods Clinical data were reviewed for 20 patients with PBC cirrhosis and 16 with AIH cirrhosis. Immunohistochemistry for IgM and IgG was performed on representative blocks of explanted livers. Three high-power fields with the highest concentration of IgG- and IgM-positive plasma cells were counted and compared. Results The average number of IgM-positive plasma cells was significantly higher in PBC explants (7.3) than in AIH (1.8) (P = .001). There was no significant difference in the average number of IgG-positive plasma cells in PBC (2.5) and AIH (2.8) (P = .8). The IgG/IgM ratio was more likely to be less than 1.0 in PBC (17/20, 85%) compared with AIH (7/16, 44%) (P = .01). Conclusions Our study demonstrates that the absolute number of IgM plasma cells is greater in explants of cirrhotic PBC compared with AIH. These findings may be helpful in the evaluation of cryptogenic cirrhosis.

The luminal gastrointestinal tract can be a site of robust immune response in which reactive lymphoproliferative processes can sometimes be difficult to distinguish from lymphoma. In this article, we review gastrointestinal tract normal resident inflammatory cells and common nonneoplastic lymphoproliferative responses with emphasis on their differential and links to lymphoma. Topics that are covered include lymphocytic esophagitis, gastric chronic inflammation, mucosa-associated lymphoid tissue, and ulceration, small intestinal lymphoid hyperplasia, celiac disease, microscopic colitis, inflammatory bowel disease, primary immunodeficiency, graft-versus-host disease, and anti-programmed cell death protein-1 effect. We additionally present the less common differential of histiocytic processes within the gastrointestinal tract. The aim of this paper is to serve as a reference for practicing pathologists facing lymphoid, lymphoplasmacytic, or histiocytic processes in the luminal gastrointestinal tract. We hope to help the practicing pathologist distinguish benign from malignant entities and identify features requiring further workup.

Cholangiocarcinoma (CC) is an uncommon malignancy with increasing incidence and dismal prognosis. We conducted a comprehensive analysis of the CC tumor immune microenvironment (TIME) based on tumor location to identify therapeutic targets. We hypothesized that the TIME of CC would vary by primary tumor location and that high tumor infiltration by CD8+ T cells and low infiltration by M2 macrophages would be associated with improved survival. A retrospective analysis was conducted of 99 CC tumor samples surgically resected between 2000 and 2014. Tissue microarrays were constructed from each tumor and stained by immunohistochemistry for 24 markers of immune cells, immune activation or inhibition, programmed cell death-ligand 1, and mesothelin. Most tumors were amply infiltrated with by CD4+, CD8+, and FoxP3+ T cells, as well as by myeloid cells. Mesothelin expression ≥1+ by immunohistochemistry was found in 68% of tumors. We identified higher densities of M1 macrophages in primary distal extrahepatic CC, as well as metastatic lesions. Mesothelin expression was also significantly higher in distal extrahepatic CC. There was no association with survival of infiltration by CD4+, CD8+, or FoxP3+ T cells, mesothelin expression, or programmed cell death-ligand 1 percentage expression, however, high CD14+ myeloid cells and high CD163+ M2 macrophages were associated with worse survival. In conclusion, the CC TIME is a heterogenous milieu highly infiltrated by innate and adaptive immune cells, which differs based on primary tumor location and between primary tumors and metastatic lesions. The correlation of intratumoral M2 macrophages and myeloid cells with a worse prognosis may suggest promising immunotherapeutic targets in CC.

Background The Accreditation Council for Graduate Medical Education requires milestone reporting of the Six General Core Competencies. Additionally, Graduate Medical Education (GME) is transitioning to adopt competency-based education methodologies including entrustable professional activities (EPAs) for objective, observable, and measurable milestone progression. The College of American Pathologists published 19 EPAs, including one for transfusion-related adverse events. This survey study includes developing EPAs for transfusion reaction evaluation and assessing residents before and after implementing these EPAs. Study design and methods Three transfusion reaction EPAs were developed and implemented in July 2018 for the Postgraduate Year (PGY) 2 pathology residents. An online, anonymous survey was sent to all 21 pathology trainees before and one year after EPA implementation. In July 2018 and August 2019, each survey included the same six multiple-choice, single-response, confidence questions, with a rating scale of extremely, very, slightly, or not at all confident. This study was approved by the hospital's Institutional Review Board for Health Sciences Research and GME Committee. Results Analysis was performed on PGY2-4 residents. In 2018, 13 of 20 participants were analyzed. In 2019, 15 of 19 participants were analyzed. Number and percentage of responses were reported. The results showed an increase in trainee confidence, with the greatest improvement among the first class to use the EPAs. Conclusion EPAs provide an effective framework for objective and measurable progression of trainees. One year after the implementation of transfusion reaction EPAs at our site, the trainees showed enhanced confidence levels in handling Blood Bank and Transfusion Medicine Services coverage.

We report a case of an unusual and aggressive gamma delta T-cell lymphoproliferative disorder/lymphoma presenting in the skin that lacked the expected cytotoxic markers and had increased expression of CD5, CD20, CD79a, CD30, and PD-1 without CD56. Monoclonal TCR-γ gene rearrangement was identified. A computed tomography scan of the chest, abdomen, and pelvis revealed a 7.7-cm soft-tissue inguinal mass and prominent retroperitoneal and pelvic lymphadenopathy, without hepatosplenomegaly. Flow cytometry finding on peripheral blood was normal. The clinical, morphologic, and immunophenotypic features of this case defy the current World Health Organization and European Organization for Research and Treatment of Cancer classifications, and a similar case has not been reported previously.

Anal squamous cell carcinomas (ASCCs) frequently harbor human papillomavirus (HPV), most commonly high-risk (HR-) HPV type 16. While p16 immunohistochemistry (IHC) is typically used as a surrogate for HR-HPV status in the oropharynx and cervix, its overexpression can also occur as a result of oncogenic stress and sometimes prove nonspecific. There have been recent investigations into the use of HPV RNA in situ hybridization (RISH) assays as an alternative method, which have shown robust results for squamous cell carcinomas of the oropharynx and cervix. Our study evaluated HPV RISH and p16 IHC in 50 ASCCs, as well as the clinicopathologic features of ASCC relative to HPV status. We found that HPV RISH and p16 IHC were closely in agreement with 96% concordance. Using the 2 methodologies, 78% of ASCCs were HR-HPV positive, 10% were low-risk HPV positive, and 12% were HPV-negative. None of our cases showed co-infection across HR-HPV and low-risk HPV. ASCCs that were not related to HR-HPV were more likely to have a typical keratinizing morphology (P=0.05) and more likely to involve the perianal area (P=0.006). HPV-negative cases were particularly aggressive with high rates of metastases and patient death within 2 years of diagnosis. Overall, HPV RISH appears to be a reliable methodology for testing, and HPV status may have implications for prognostication of ASCCs.

Lynch syndrome (LS) is defined by germline mutations in DNA mismatch repair (MMR) genes, and affected patients are at high risk for multiple cancers. Reflexive testing for MMR protein loss by immunohistochemistry (IHC) is currently only recommended for colorectal and endometrial cancers, although upper tract urothelial carcinoma (UTUC) is the third-most common malignancy in patients with LS. To study the suitability of universal MMR IHC screening for UTUC, we investigated MMR expression and microsatellite status in UTUC in comparison to bladder UC (BUC), and evaluated the clinicopathologic features of UTUC. We found that 9% of UTUC showed MMR IHC loss (8 MSH6 alone; 1 MSH2 and MSH6; 1 MLH1 and PMS2; n=117) compared with 1% of BUC (1 MSH6 alone; n=160) (P=0.001). Of these, 4/10 (40%) of UTUC (3% overall; 3 MSH6 alone; 1 MLH1 and PMS2) and none (0%) of BUC had high microsatellite instability on molecular testing (P=0.03). The only predictive clinicopathologic feature for MMR loss was a personal history of colorectal cancer (P=0.0003). However, UTUC presents at a similar age to colon carcinoma in LS and thus UTUC may be the sentinel event in some patients. Combining our results with those of other studies suggests that 1% to 3% of all UTUC cases may represent LS-associated carcinoma. LS accounts for 2% to 6% of both colorectal and endometrial cancers. As LS likely accounts for a similar percentage of UTUC, we suggest that reflexive MMR IHC screening followed by microsatellite instability testing be included in diagnostic guidelines for all UTUC.

Complete response after acute myeloid leukemia (AML) therapy historically requires a decrease in bone marrow (BM) blasts to 200 cells), blast count, trilineage hematopoiesis, dysplastic features, focal/patchy disease, and any non-hematopoietic or alternative diagnoses that would not have been discovered by the associated MFC study. The MFC data for each case was separately reviewed by two hematopathologists. Six of the 47 cases showed >5% blasts by morphology (range 8%-70%); in all six cases, >5% abnormal blasts were also identified by MFC (range 23%-78%). Of cases with 5% abnormal blasts in four cases and 5% blasts). In the remaining three cases with dysplasia, ancillary molecular studies supported molecular evidence of residual disease in one case (NPM1 mutation and FLT3-ITD positivity by PCR). No unexpected carcinomas or other findings that would not be detected by the associated MFC study were identified. In conclusion, in our study, morphologic evaluation did not definitively identify any additional cases of residual/recurrent AML that were not identified by MFC. Morphologic evaluation detected dysplasia without abnormal blasts in three cases; however, the significance was unclear without supportive molecular studies. Reducing the number of cases for morphologic evaluation could save resources and improve turnaround time if MFC can provide the relevant details to assess response.

ObjectivesAlthough germline mutations of mismatch repair (MMR) genes (Lynch syndrome) are not typically associated with cholangiocarcinomas, the US Food and Drug Administration recently approved the use of pembrolizumab in patients with advanced solid tumors at all sites that show MMR deficiency or associated high microsatellite instability.MethodsWe analyzed 96 cases of intra- and extrahepatic cholangiocarcinomas for morphology using H&E and for MMR status using immunohistochemical staining. We submitted any results with MMR loss for microsatellite instability testing.ResultsWe found that 6% of samples showed MMR deficiency. The best predictive factor was a nontypical infiltrating pattern of invasion (P < .0001). No patients with MMR deficiency had a history of a cancer typically associated with Lynch syndrome.ConclusionsSolid, mucinous, or signet-ring appearance of a cholangiocarcinoma should prompt MMR testing for immunotherapy options but should not necessarily raise concern about Lynch syndrome.

Helicobacter infection is considered the major predisposing factor for gastric mucosa-associated lymphoid tissue (MALT) lymphoma with initial infection likely occurring in childhood. Primary gastric MALT lymphoma most commonly occurs in patients older than 50 years which is attributed to the lengthy chronic infection time required before the development of MALT lymphoma. Our study analyzes the histologic features and presence of immunoglobulin heavy chain (IGH) clonality in Helicobacter-associated chronic gastritis (62 cases) and Helicobacter-negative chronic gastritis (17 cases) biopsies within the pediatric population, diagnosed between 1996 and 2018. Helicobacter-associated gastritis was more likely to show active inflammation (P=0.01), with no significant difference in number of germinal centers or the strength, linear property, or depth of the inflammatory infiltrate. In total, 47% (29/62) of the Helicobacter-associated cases had at least 1 lymphoepithelial lesion, equivocal or definitive (a modified Wotherspoon score of 3 to 5), compared with 24% (4/17) of the Helicobacter-negative cases (P=0.5). All cases with lymphoepithelial lesions were assessed for IGH clonality, showing the presence of monoclonality in 27% (8/30) of evaluable cases. None of our patients were diagnosed with gastric lymphoma within available follow-up data. Although 4% of our cases could be considered MALT lymphoma in an adult patient based on prominent lymphoepithelial lesions and IGH monoclonality, caution is advised when diagnosing lymphoma in the pediatric population given the good prognosis of Helicobacter-associated gastritis in this age group. It is unclear if these monoclonal lymphoid proliferations require close follow-up.

Objectives Cross-species conservation of sleep-like behaviors predicts the presence of conserved molecular mechanisms underlying sleep. However, limited experimental evidence of conservation exists. Here, this prediction is tested directly. Measurements and results During lethargus, Caenorhabditis elegans spontaneously sleep in short bouts that are interspersed with bouts of spontaneous locomotion. We identified 26 genes required for Drosophila melanogaster sleep. Twenty orthologous C. elegans genes were selected based on similarity. Their effect on C. elegans sleep and arousal during the last larval lethargus was assessed. The 20 most similar genes altered both the quantity of sleep and arousal thresholds. In 18 cases, the direction of change was concordant with Drosophila studies published previously. Additionally, we delineated a conserved genetic pathway by which dopamine regulates sleep and arousal. In C. elegans neurons, G-alpha S, adenylyl cyclase, and protein kinase A act downstream of D1 dopamine receptors to regulate these behaviors. Finally, a quantitative analysis of genes examined herein revealed that C. elegans arousal thresholds were directly correlated with amount of sleep during lethargus. However, bout duration varies little and was not correlated with arousal thresholds. Conclusions The comprehensive analysis presented here suggests that conserved genes and pathways are required for sleep in invertebrates and, likely, across the entire animal kingdom. The genetic pathway delineated in this study implicates G-alpha S and previously known genes downstream of dopamine signaling in sleep. Quantitative analysis of various components of quiescence suggests that interdependent or identical cellular and molecular mechanisms are likely to regulate both arousal and sleep entry.