BACKGROUND:Gastric well-differentiated neuroendocrine tumors (gNETs) arising in association with prolonged acid suppressant drug use, including proton pump inhibitors (PPIs) and/or histamine type 2 receptor antagonists (H2RAs), are an emerging subtype of gNET presumably arising from drug-related chronic hypergastrinemia. The clinicopathologic features of these gNETs were examined in an institutional cohort. DESIGN:23 patients with 39 gNETs were included. gNETs were considered acid suppressant-associated in patients with documented PPI and/or H2RA use for >1 year or ≥2 features of drug effect (parietal and/or enterochromaffin-like (ECL)-cell hyperplasia and/or elevated serum gastrin) in those with limited clinical information. Histomorphologic features were assessed. RESULTS:The median patient age was 65 years (range: 37-84) with a female predominance (female:male 1.6:1). Hypergastrinemia was present in 69 % (11/16) of tested patients (median: 232 pg/mL, range 130-407). In patients with documented drug use (n = 16), 50 % used for ≥10 years. Most gNETs were ≤1 cm and were restricted to the mucosa. Regional lymph node metastasis was rare (2/21; 9 %). Unconventional morphology included 15 % with secretory cribriform morphology and 3 % with mixed pseudopapillary and conventional morphology. 30 % of patients had multiple tumors diagnosed over spans ranging from 0.75 to 9 years, though none developed distant disease (median follow-up: 3 years, range 0-15), including 2 patients with lymph node metastasis (10- and 13-year follow-up). CONCLUSIONS:Acid suppressant-associated gNETs have an indolent course, are often multiple, and are frequently associated with very prolonged PPI/H2RA use. Unconventional morphologies like those described in type 1 gNETs may be observed.

BACKGROUND:Autoimmune metaplastic atrophic gastritis (AMAG) causes pulmonary trans-differentiation of the gastric mucosa and is known to increase the risk of developing gastric adenocarcinoma. AMAG-associated gastric adenocarcinomas were examined for immunoreactivity for TTF-1 and Napsin A. DESIGN:Eighteen AMAG-associated gastric adenocarcinomas and 36 non-AMAG-associated gastric adenocarcinomas were stained for TTF-1 (clones SP141 and 8G7G3/1) and Napsin A (clone 1P64) by immunohistochemistry. AMAG stage and staining patterns were characterized. RESULTS:The AMAG group was older (mean age 74 vs. 65 years) and was not significantly different with regard to sex or tumour differentiation. Zero (0%) AMAG cases were classified as early phase, four (22%) as florid phase and 14 (78%) as end stage. AMAG-associated adenocarcinomas showed more frequent TTF-1 immunoreactivity compared to control adenocarcinomas in both clone SP141 (39% vs. 11%; P = 0.04) and 8G7G3/1 (22% vs. 6%; P = 0.17). AMAG-associated adenocarcinomas showed more frequent Napsin A immunoreactivity compared to control adenocarcinomas (28% vs. 0%; P < 0.01). Immunoreactivity in AMAG-associated adenocarcinomas was patchy, ranging from 1% to 20% of tumour cells staining positive (1+ to 3+ intensity). In the AMAG cases with background gastric mucosa (n = 14), the background showed TTF-1 positive foci in seven (50%) cases (both clones) versus one (3%; clone SP141) to two (6%; clone 8G7G3/1) of 33 controls (P < 0.01) and Napsin A positive foci in five (36%) cases versus zero (0%) controls (P < 0.01). Staining in background mucosa was also patchy, involving 1%-10% of gastric glands without intestinal metaplasia. CONCLUSION:TTF-1 and Napsin A immunoreactivity was present in the background gastric mucosa almost exclusively in the AMAG-associated cases. This immunoreactivity is also present in AMAG-associated adenocarcinomas more commonly than non-AMAG-associated adenocarcinomas. This knowledge may aid pathologists in avoiding the pitfall of diagnosing metastatic lung cancer, as the expression is patchy and may also be seen in atrophic background mucosa.

Liver biopsy is common before heart transplantation to assess for advanced fibrosis that could require combined heart-liver transplantation. While congestive hepatopathy is common in these biopsies, little is known about what happens in the native liver after heart transplantation. In this study, 1300 adult heart explants were identified at a single institution, 38 of which had subsequent native liver biopsies (2.9 %), including 31 after orthotopic heart transplantation (OHT) and 7 after total artificial heart (TAH) implantation. Presentation was variable, but similar overall between post-OHT and post-TAH patients, with elevated liver function tests being the most common indication for liver biopsy (15/38; 39.5 %), and AST levels being significantly higher in post-TAH patients than post-OHT patients (mean: 172.4 vs. 59.8 U/L, respectively; p = 0.0077). A wide variety of histological patterns was seen, but the most common was a vascular outflow impairment pattern in 11/38 (28.9 %) patients. Fibrosis was predominantly mild (23/38; 60.5 %), with advanced fibrosis in 5 (13.2 %), no fibrosis in 6 (15.8 %), and insufficient parenchyma for evaluation in 4 (10.5 %). Fewer than half of patients with vascular outflow impairment pattern had a clinical diagnosis of heart failure, suggesting alternative etiologies of vascular injury in post-OHT/TAH patients.

Aims Metastatic tumors to the stomach can mimic primary gastric adenocarcinoma or be subtle and difficult to identify. The current study aimed to characterize the clinicopathology of metastases to the stomach to aid in diagnosis. Methods and Results Forty-three metastatic tumors and 30 primary gastric adenocarcinoma cases were reviewed. Metastases originated from numerous primaries with the most common being mammary (n=17) or melanoma (n=9). The gastric metastasis represented the initial diagnosis for 9 (21%) cases without previous history of malignancy. The median age at diagnosis was similar (metastatic 66 years; primary 67.5 years; P=0.42). The most common indication for procedure was abdominal pain (23%; P=0.95) in metastases and melena (43%; P<0.01) in primaries. Procedural findings suggestive of metastasis over primary adenocarcinoma were multiple lesions (23% versus 0%; P=0.01), non-mass forming mucosal changes (30% versus 0%; P<0.01), submucosal nodularity (14% versus 0%; P=0.09), and absence of ulceration (9% versus 53%; P<0.01). Histologic findings less commonly seen in metastasis were mucosal layer involvement (86% versus 100%; P=0.09), ulceration (40% versus 70%; P=0.02), surface epithelial involvement/colonization by tumor (12% versus 60%; P<0.01), intestinal metaplasia (9% versus 53%; P<0.01), background dysplasia (0% versus 30%; P<0.01), and Helicobacter pylori infection (0% versus 20%; P<0.01). Lymphovascular invasion had similar prevalence (metastatic 23%; primary 20%; P=0.70). Conclusions Metastasis to the stomach included a variety of primary sites and was not infrequently the initial diagnosis. Patient demographics were similar to primary adenocarcinoma. Multiple lesions, non-mass forming mucosal changes, and/or submucosal nodularity were more common in metastasis. Histologically, the absence of surface epithelial involvement, ulceration, intestinal metaplasia, background dysplasia, or H. pylori infection can raise suspicion for metastasis.

We have developed and now report on the first functional global midnolin knockout mouse model. We found that global heterozygous midnolin knockout attenuated the severity of nonalcoholic fatty liver disease (NAFLD) in mice fed a Western-style diet, high in fat, cholesterol, and fructose, and this attenuation in disease was associated with significantly reduced levels of large lipid droplets, hepatic free cholesterol, and serum LDL, with significantly differential gene expression involved in cholesterol/lipid metabolism.

List of RT-RTPCR primers used in the manuscript.

PDF file - 180K, List of primer sets used for RNA analysis in the manuscript.

PDF file - 86K, Results from the WNT signaling pathway RT2 profiler PCR array between TEN+EtOH and TEN control livers.

Background: Spindle cell neoplasms are a diagnostically challenging entity, and often morphology and immunohistochemistry (IHC) are insufficient to definitively classify them.Next generation sequencing (NGS) offers the potential to refine diagnoses as well as therapeutic options.Somatic NF1 mutations have been reported in numerous spindle cell malignancies.We present our institutional experience with diagnostically challenging spindle cell neoplasms in which NF1 mutations were identified.Design: An IRB-approved retrospective review of our institutional database from 2018-2021 was performed, identifying all cases submitted with a potential diagnosis of sarcoma in which an NF1 truncating mutation was detected via Foundation One testing or a DNA/RNA based NGS assay.Clinical and pathologic features of each case were collected.Results: Of a total of 248 cases tested, 18 (7.2%)were identified as having NF1 truncating mutations.Final integrated diagnoses included 4 malignant peripheral nerve sheath tumor (22%), 3 pleomorphic undifferentiated sarcoma (22%), 3 desmoplastic melanoma (DM) (16.7%), 2 malignant phyllodes tumor (11%), 2 pleomorphic dermal sarcoma (11%), 1 neurofibroma, 1 high-grade myxofibrosarcoma, 1 pleomorphic rhabdomyosarcoma, and 1 unclassified.In 3 cases, the NGS data changed the final diagnosis compared to the original diagnosis of high-grade sarcoma.All 3 cases were ultimately classified as DM; each possessed >1 somatic NF1 truncating mutation along with an ultraviolet (UV) signature, suggestive of desmoplastic melanoma.Two of these three cases were negative for S-100, Sox10 and BRAF by IHC.Conclusions: NGS is an extremely powerful and potentially underused tool in the pathologist's toolbox.When conventional methods of IHC and morphologic analysis fail to render a diagnosis, NGS may provide the final piece of the diagnostic puzzle.Here we identified three cases for which the NGS results significantly altered the primary pathologic diagnosis leading to a more accurate diagnosis, treatment plan, and ultimately the most optimal patient care possible.

Background:The correlation of intra-operative frozen section diagnosis with the final diagnosis on permanent sections plays a significant role in evaluating liver biopsies for transplant evaluation.The purpose of this study is to investigate the discrepancy between the intraoperative frozen section and permanent section assessment of hepatic steatosis.We aim to reduce errors during frozen section interpretation as it could exclude an otherwise acceptable organ.Design: A retrospective analysis was performed on all frozen sections performed on liver specimens in our institution between April 2017 and July 2021.A total of 264 cases were received.Out of them, 61 cases were included in the study, while 203 cases were excluded due to the concern for malignancy.We then calculated the discrepancy rate between frozen and permanent sections.Results: Out of 61 cases, 20 (32%) cases showed discrepancies between the frozen and the permanent sections.13 (65%) cases showed discrepancies in macrovesicular steatosis, ranging from 1-25%.Four cases (6%) showed a major discrepancy of >10%.In all cases, the percentage of macrovesicular steatosis was described more during the intraoperative consultation than the permanent section.Sixteen (80%) cases showed discrepancies in microvesicular steatosis ranging from 3-30%, and 9 (15%) cases showed a major discrepancy of >10%.Contrary to macrovesicular steatosis, microvesicular steatosis was described more in the permanent section than the frozen section in some (2/20) cases. Conclusions:Our study found considerable discrepancies for both macrovesicular and microvesicular steatosis interpretation between frozen and permanent sections.The extent of steatosis can be misinterpreted during intraoperative consultation because of artifacts produced during frozen section due to multiple factors, including air drying quickly, water droplets freezing in the tissue during processing and much larger size of the hepatocytes with steatosis as compared to normal hepatocytes.Although a significant degree of microvesicular steatosis is not considered an absolute contraindication to transplantation, it is considered a risk factor for early hepatic dysfunction after orthotopic liver transplantation in patients with infections and other immunocompromised conditions.Awareness of these issues can help increase the diagnostic accuracy of donor liver biopsies during intraoperative frozen section interpretation.

Background: Despite an excellent long-term prognosis, up to 20% of patients with papillary thyroid carcinoma (PTC) experience regional or distant recurrence.About one third of these recurrences become radioiodine-refractory (RAIR), which significantly worsens prognosis.BRAF V600E and TERT promoter mutations were recently identified as predictors of RAIR in distant metastases of PTC.Locoregionally recurrent PTCs are not infrequent, however there is a lack of knowledge about molecular events in these lesions due to rarity of sampling.We aimed to study histopathological characteristics, PD-L1 expression, BRAF-TERT signature, and clinical correlates in RAIR cervical recurrences of PTC.Design: A total of 66 cases (mean age -56.1, sex ratio -0.37) were qualified as eligible from a cohort of 1857 patients with PTC who received post-thyroidectomy RAI ablation.Locoregional recurrence was defined as a histopathologically confirmed tumor recurrence within the neck.A case was considered RAIR if the patient had an elevated serum thyroglobulin (>10 ng/ml) under a high thyrotropin level with structural disease in the setting of a negative RAI scan, or disease progressed after receiving more than 600 mCi of RAI.We performed pyrosequencing for BRAF V600E and TERT promoter C228T and C250T mutations.PD-L1 expression was evaluated with Ventana SP263 clone.Results: Histologically, most of the cervical recurrences were of lymph node origin, with frequent extranodal extension.Predominant patterns were papillary, tall cell, and solid.TERT promoter mutations were found in 28/65 (43%) cases, including 23 cases with TERT C228T and 5 cases with TERT C250T.BRAF V600E mutation was found in 52/66 (78.8%) cases.Coexistence of TERT promoter and BRAF mutations was found in 25/66 (37.9%) recurrent PTCs, while 11/66 (16.7%) cases were BRAF-/TERT-.PD-L1 expression (> 1%) was detected in 21/36 cases available for evaluation, including 10/36 cases with immunoexpression in over 25% cancer cells.On a mean follow-up of 63.5 months, 18/66 (27.3%) patients died of disease.TERT promoter mutation and BRAF/TERT combination were found less frequently in surviving patients; however only BRAF/TERT co-mutation was statistically associated with a death by disease (p = 0.04).Conclusions: This is the first study describing the high prevalence of BRAF and TERT promoter mutations in a carefully selected cohort of RAIR locoregional recurrences of PTC.RAIR tumors showed frequent PD-L1 expression, which may have clinical implications.

Background and study aims  Data are lacking on the natural history of gastrointestinal tract schwannomas. We aimed to study the natural history of all gastrointestinal schwannomas including location, diagnosis, management, and long-term outcomes. Patients and methods  Patients with a pathological diagnosis of gastrointestinal schwannoma between January 2000 and March 2020 were identified. Data on baseline demographics, presentations, associated malignancies, malignant transformation, treatment, and recurrence were collected. Results  Our cohort consisted of 44 patients with a mean age of 58.6 years, with 63.6 % women and 84.1 % White. The stomach (38.6 %) was the most common location followed by the colorectum (31.8 %). Only 22.7 % of patients were symptomatic and 22.0 % had a personal history of other malignancies. Tissue diagnosis was obtained via endoscopy in 47.7 % and from surgical pathology in 52.3 %. On histology, 65.9 % of the tumors were solid, 11.4 % had mixed features, and 2.3 % had necrosis. SP100 was tested in all but one patient and was positive in all. Mean Ki-67 in 12 patients with tumors measuring ≥ 2 cm was 3.0 % indicating a low proliferation rate. Of the patients, 77.3 % had surgery and 18.2 % underwent endoscopic resection. At a mean follow-up of 5.0 ± 4.31 years, there was no malignant transformation, recurrence or mortality associated with gastrointestinal schwannomas. Conclusions  Gastrointestinal schwannomas are diagnosed in the fifth to sixth decade with predominance in women and Whites. They are benign, mostly asymptomatic, and diagnosed incidentally. Asymptomatic gastrointestinal schwannomas including lesions ≥ 2 cm in size do not appear to need further monitoring or intervention. Patients with them should be counseled to remain up to date with routine screening guidelines pertaining to the colon, breast, and lung cancer due to the high incidence of concomitant malignancy.

Background:Case based learning provides a practical structure to aid in the understanding and retention of abstract concepts.We identified a need for the creation of a centralized and accessible resource to retain clinical pathology (CP) cases that demonstrate important educational concepts.Historically, a component of our microbiology (MICRO) resident curriculum included the creation of an educational "newsletter" detailing an interesting case from the resident's rotation.This included a multiple-choice question (MCQ) and discussion.Beginning in 2018, residents presented 1-2 interesting cases per CP rotation during weekly CP Call Rounds.These newsletters and presentations contained valuable case-based educational material which was not catalogued, and thus not easily accessible to current or future residents.Design: Modeled after our institution's existing "Surgical Pathology Unknown Conference" website, a "Clinical Pathology Unknowns" website was created where users could view a clinical vignette and relevant figures, interact with a MCQ, and review a discussion.Google Analytics ® (GA) tracked website usage.Revisions of the CP Call Rounds presentation guidelines included creation of a MCQ with discussion for incorporation into the website.The Department established a team of "CP Unknowns" residents, who are responsible for posting cases, as well as ensuring all cases are: (1) approved by subspecialty CP faculty; and(2) fully de-identified.Results: A pilot version of the website went live on the internal network in May 2019.After go-live, the website link was distributed to pathology residents, CP faculty, transfusion medicine (TM) and MICRO lab staff, and infectious disease faculty.As of August 2021, 52 TM, 42 MICRO, 10 clinical chemistry, 2 hematopathology, and 1 hematology/coagulation cases have been posted.From go-live to August 2021, GA tracked 3,375 page views and 2,491 unique page views.Conclusions: Herein we describe our experience designing and implementing a digital repository of CP cases.The number of cases posted over the pilot phase increased after formal incorporation of CP Call Rounds presentations.Preliminary website utilization metrics highlight robust website use.Future directions include surveying website users (i.e.pathology and non-pathology trainees, laboratory professionals, faculty) to assess patterns and motives for website use.We also expect to make the website public to benefit the broader pathology community.