Keratin 17 is a prognostic and predictive biomarker in pancreatic ductal adenocarcinoma.

OBJECTIVES: To determine the role of keratin 17 (K17) as a predictive biomarker for response to chemotherapy by defining thresholds of K17 expression based on immunohistochemical tests that could be used to optimize therapeutic intervention for patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: We profiled K17 expression, a hallmark of the basal molecular subtype of PDAC, by immunohistochemistry in 2 cohorts of formalin-fixed, paraffin-embedded PDACs (n = 305). We determined a K17 threshold of expression to optimize prognostic stratification according to the lowest Akaike information criterion and explored the potential relationship between K17 and chemoresistance by multivariate predictive analyses. RESULTS: Patients with advanced-stage, low K17 PDACs treated using 5-fluorouracil (5-FU)-based chemotherapeutic regimens had 3-fold longer survival than corresponding cases treated with gemcitabine-based chemotherapy. By contrast, PDACs with high K17 did not respond to either regimen. The predictive value of K17 was independent of tumor mutation status and other clinicopathologic variables. CONCLUSIONS: The detection of K17 in 10% or greater of PDAC cells identified patients with shortest survival. Among patients with low K17 PDACs, 5-FU-based treatment was more likely than gemcitabine-based therapies to extend survival.

5-Hydroxymethylcytosine (5-hmC) loss is a marker of malignancy in biliary neoplasms.

OBJECTIVES: Adenocarcinomas of the biliary tract frequently present diagnostic challenges because of their histologic overlap with benign and preinvasive lesions. The molecular profiles of biliary adenocarcinomas vary by anatomical location. Variations in IDH1/2, common in intrahepatic cholangiocarcinoma, can lead to defective production of 5-hydroxymethylcytosine (5-hmC). Limited ancillary studies are available for biliary adenocarcinomas, and loss of 5-hmC staining could serve as a helpful ancillary diagnostic tool for biliary tract malignancies. METHODS: We evaluated 93 cases-20 benign biliary lesions, 15 preinvasive biliary neoplasms, 46 invasive biliary carcinomas, and 12 pancreatic adenocarcinomas-for 5-hmC staining. Preoperative biopsies from 16 cases of biliary carcinoma were also stained. Sixteen nonneoplastic/reactive bile duct biopsies served as controls. RESULTS: Loss of 5-hmC was seen in 41 of 46 (89.1%) biliary malignancies vs 0 of 20 benign tumors (P < .001), for a sensitivity and specificity of 89.1% and 100%, respectively. Intrahepatic cholangiocarcinoma showed loss of 5-hmC in 11 of 13 (84.6%) cases, similar to the 30 of 33 (90.9%) cases in other biliary adenocarcinomas (P = .61). Similarly, 5-hmC loss was more frequent in distal bile duct adenocarcinomas than in pancreatic ductal adenocarcinomas, at 15 of 17 (88.2%) vs 4 of 12 (33.3%), respectively (P = .0045). There was no difference in the frequency of 5-hmC loss in patients that received neoadjuvant therapy vs those who did not (90.9% vs 88.6%, P > .99). 5-hmC immunohistochemistry in preoperative biopsies was concordant with the resection specimen in 81.3% (13/16) of cases. CONCLUSIONS: Loss of 5-hmC is not unique to intrahepatic cholangiocarcinoma among biliary carcinomas, but is a useful diagnostic marker differentiating malignancies of the biliary tree from benign mimics.

Markedly increased duodenal villous surface apoptosis in patients taking pre-exposure prophylaxis (PrEP) against human immunodeficiency virus.

AIMS: Pre-exposure prophylaxis (PrEP) consists of combination antiretroviral therapy and is increasingly utilized to prevent human immunodeficiency virus (HIV) in high-risk populations. Two index cases noted during routine care showed markedly increased duodenal villous surface apoptosis in patients on PrEP. We sought to examine the prevalence of this finding and identify any clinicopathologic correlations. METHODS: Gastrointestinal biopsy specimens from 23 male patients aged 18-40 years taking PrEP and 23 control patients were reviewed. Patients with HIV, inflammatory gastrointestinal diseases, and celiac disease were excluded. Apoptoses were counted on surface epithelium and deep crypts. The highest apoptotic body count per tissue fragment was recorded. Clusters were defined as groups of ≥5 apoptoses. Apoptotic counts between patients taking PrEP and controls were compared using t-tests. RESULTS: In PrEP patients, the median age was 35 years (range 25-40) and 83% (19/23) were white. The control patients were demographically similar (median age: 32 years [range 23-40]; 70% [16/23] white). Duodenal apoptosis in villous surface epithelium was increased in PrEP patients, with 14/23 (60.9%) patients having ≥10 surface apoptoses compared to 2/23 (8.7%) controls (P = 2.1 × 10-3 ) and 14/23 (61%) having clusters compared to 3/23 (13%) controls (P = 2.0 × 10-3 ). There was no significant association between increased surface apoptosis or clusters and clinical symptoms or duration of PrEP use. CONCLUSION: Markedly increased villous surface apoptosis, particularly in clusters, is often seen in the duodenum of patients taking PrEP. Although the mechanism and significance are unknown, knowledge of this peculiar finding may prevent unnecessary additional testing.

Arginase-1 is More Specific Than Hepatocyte Paraffin 1 for Differentiating Hepatocellular Carcinomas With Cytoplasmic Clearing from Nonhepatocellular Clear Cell Tumors in Liver Biopsies.

Arginase-1 (Arg1) and hepatocyte paraffin antigen 1 (HepPar1) are specific and sensitive markers of hepatocellular differentiation. HepPar1 is a granular cytoplasmic immunostain that may be negative in hepatocellular carcinoma (HCC) with cytoplasmic clearing. Arg1 shows uniform cytoplasmic positivity and frequent nuclear positivity. This study was undertaken to determine the staining pattern of Arg1 in HCC with cytoplasmic clearing and compare its use to HepPar1. Fifteen resected HCCs with cytoplasmic clearing and 31 biopsies of clear cell liver tumors (14 HCCs and 17 nonhepatocellular tumors) were identified. Resections were stained with Arg1 to characterize the pattern, intensity, and extent of Arg1 positivity. Biopsies were stained with Arg1 (n=31) and HepPar1 (n=28). In all, 13/15 resected and 11/14 biopsied HCCs with cytoplasmic clearing showed nuclear positivity for Arg1. Both Arg1 and HepPar1 stained significantly more HCCs than nonhepatocellular tumors (13/14 and 11/12, respectively, with P <0.0001 and P =0.0018, respectively). However, HepPar1 stained significantly more nonhepatocellular tumors (5/12) than Arg1 (0/17, P =0.0445). Arg1 frequently displayed nuclear positivity, and interobserver agreement was better for Arg1 ( K =0.93 vs. 0.79). Overall, Arg1 is more specific than HepPar1 for differentiating HCC with cytoplasmic clearing from nonhepatocellular clear cell tumors in the liver. Its staining characteristics, including nuclear positivity, make it easier to interpret in combination with morphology, improving interobserver variability, and it stains significantly fewer mimics than HepPar1.

Capecitabine-induced Gastrointestinal Injury Shows a Graft-Versus-Host Disease (GVHD)-like Pattern.

Capecitabine is a commonly used oral chemotherapeutic agent. Gastrointestinal (GI) side effects are clinically well-known, however, the histopathologic changes have not been comprehensively studied. This study describes the largest case series (8 patients) characterizing the histopathology of capecitabine-induced GI injury. All patients were adults (median age: 64.5 y, range: 61 to 76 y) and there was gender parity. Patients were receiving treatment for malignancies of the colorectum (n=5), breast (n=1), pancreas (n=1), and appendix (n=1). All had GI symptoms, including 7 with diarrhea and abdominal pain and 1 with melena. Five of 8 (63%) showed graft-versus-host disease (GVHD)-like histologic changes in small intestinal and/or colonic biopsies characterized by crypt disarray and dropout, crypt atrophy, dilated crypts lined by attenuated epithelium, and increased crypt apoptosis. Neuroendocrine cell aggregates were present in 4 of 5 cases. Four of 5 showed patchy prominence in lamina propria eosinophils. One patient receiving concomitant radiation therapy had a small intestinal biopsy showing regenerative changes. Two patients had histologically unremarkable biopsies. On follow-up, capecitabine was discontinued or dose-reduced in all patients. Three of 5 patients with a GVHD-like pattern had clinical improvement, whereas 2 died shortly after biopsy. One with regenerative changes also had radiation dose reduction and improved clinically. Two with unremarkable biopsies improved symptomatically. In summary, capecitabine-related GI injury shows a GVHD-like pattern. Knowledge of this is important to confirm the diagnosis as patients typically improve with dose reduction or discontinuation of the drug.

Glycogenic hepatopathy is associated with type 1 diabetes mellitus in only a minority of cases in a contemporary adult population.

OBJECTIVES: This study examines the clinical-pathological profiles of patients with glycogenic hepatopathy in a contemporary cohort of patients at an adult acute care hospital. METHODS: Liver biopsies with glycogenic hepatopathy were retrieved from the departmental surgical pathology database, the histological findings were studied, and the clinical findings were reviewed. RESULTS: Five cases of glycogenic hepatopathy were found, including cases associated with type 1 diabetes mellitus (n = 1), type 2 diabetes mellitus (n = 1), corticosteroids (n = 2), and anorexia (n = 2, including the patient with type 1 diabetes). AST and ALT were normal to mildly elevated (13-115 U/L and 7-126 U/L, respectively). Trace ascites was present in two patients. Hepatomegaly was only present in the patient with type 1 diabetes at the time of diagnosis. CONCLUSIONS: Four of five cases were associated with etiologies other than type 1 diabetes, which is widely reported as the most common etiology of glycogenic hepatopathy. This study suggests that etiologies currently only rarely recognized may actually be more common causes of glycogenic hepatopathy than type 1 diabetes in a contemporary adult population. It is important not only to recognize that these rarely reported causes of glycogenic hepatopathy may be underrecognized, but that the clinical presentation may also be mild.

Increasing Pancreatic Cancer Incidence in Young Women in the United States: A Population-Based Time-Trend Analysis, 2001-2018.

BACKGROUND & AIMS: Previous studies have shown an increasing incidence of pancreatic cancer (PC), especially in younger women; however, this has not been externally validated. In addition, there are limited data about contributing factors to this trend. We report age and sex-specific time-trend analysis of PC age-adjusted incidence rates (aIRs) using the National Program of Cancer Registries database without Surveillance Epidemiology and End Results data. METHODS: PC aIR, mortality rates, annual percentage change, and average annual percentage change (AAPC) were calculated and assessed for parallelism and identicalness. Age-specific analyses were conducted in older (≥55 years) and younger (<55 years) adults. PC incidence based on demographics, tumor characteristics, and mortality were evaluated in younger adults. RESULTS: A total of 454,611 patients were diagnosed with PC between 2001 and 2018 with significantly increasing aIR in women (AAPC = 1.27%) and men (AAPC = 1.14%) without a difference (P = .37). Similar results were seen in older adults. However, in younger adults (53,051 cases; 42.9% women), women experienced a greater increase in aIR than men (AAPCs = 2.36%, P < .001 vs 0.62%, P = 0.62) with nonparallel trends (P < .001) and AAPC difference of 1.74% (P < .001). This AAPC difference appears to be due to rising aIR in Blacks (2.23%; P < .001), adenocarcinoma histopathologic subtype (0.89%; P = .003), and location in the head-of-pancreas (1.64%; P < .001). PC mortality was found to be unchanged in women but decreasing in counterpart men (AAPC difference = 0.54%; P = .001). CONCLUSION: Using nationwide data, covering ≈64.5% of the U.S. population, we externally validate a rapidly increasing aIR of PC in younger women. There was a big separation of the incidence trend between women and men aged 15-34 years between 2001 and 2018 (>200% difference), and it did not show slowing down.

Tumor hyaluronan as a novel biomarker in non-small cell lung cancer: A retrospective study.

INTRODUCTION: Hyaluronan (HA) accumulation is associated with tumorigenesis and aggressive tumor behavior. AIMS: We investigated the biomarker potential of HA in non-small cell lung cancer (NSCLC). METHODS: HA levels were scored using affinity histochemistry in 137 NSCLC samples stratified by HA score ≤10, 11-20, 21-30, and >30 with HA-high defined as ≥25% expression in the extracellular matrix (ECM) of the tumor surface area. Overall survival (OS) and time to progression from initiation of taxane therapy (TTP) were compared using log-rank tests based on HA score. RESULTS: Of 122 patients with recurrent/metastatic NSCLC, 93 had mean HA scores that were not significantly different across clinicopathologic variables. Frequency of HA-high tumors did not differ by histology (34/68 adenocarcinomas vs. 12/25 squamous tumors, Fisher's p = 1.0000). Median OS for recurrent/metastatic adenocarcinoma was 35.5 months (95%, 23.6-50.3) vs. 17.9 months for squamous (95%, 12.7-37.0, log-rank test, p = 0.0165). OS was not significantly different by HA quartiles, high or low (<25) HA score and tumor histology, and HA biopsy site (all p > 0.05). Median TTP (n = 98) significantly differed by HA quartile (2.8 months for HA score ≤10; 5.0 months for 11-20; 7.9 months for 21-30; 3.9 months for >30, p = 0.0265). Improved TTP trended in HA-high over HA-low tumors (n = 98, p = 0.0911). CONCLUSION: In this NSCLC cohort, tumor HA level represents a potential biomarker for TTP, which remains a cornerstone of NSCLC therapy. Further validation is warranted to identify the HA accumulation threshold associated with clinical benefit.

The Histopathology of Anorectal Neisseria gonorrhoeae Infection.

OBJECTIVES: Neisseria gonorrhoeae infection of the anorectal tract is often asymptomatic and infrequently biopsied, but pathologists can be tasked with identifying the histologic features of possible infection. The study was undertaken to better characterize clinical and morphologic features of confirmed anorectal gonococcal infection. METHODS: From 2011 to 2020, 201 positive gonococcal nucleic acid amplification testing samples from 174 patients collected from the distal colorectum and/or anus were matched to eight patients with concurrent biopsy specimens of the distal anorectum. Complete demographic, clinical, and infectious information was collected for each biopsied patient. The histomorphologic features of each biopsy were systematically tabulated. RESULTS: All eight gonococcal cases were obtained from men who have sex with men. Each case showed at least mild acute inflammation with moderate activity identified in one case with concurrent cytomegalovirus infection. Intense lymphoplasmacytic infiltration was not commonly seen (two of eight). Half of the cases showed mucosal ulceration, and seven of eight cases demonstrated lymphoid aggregates. CONCLUSIONS: The microscopic features are mild compared with other well-described types of infectious proctitis, with most cases displaying mild acute inflammation and scattered lymphoid aggregates. These findings highlight the importance of obtaining a complete patient history and recommending additional infectious workup even when only subtle changes are present.

Claudin-18.

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.

Novel Endoscopic Polypectomy Surveillance Technique for Fundic Gland Polyps in Familial Adenomatous Polyposis Can Improve Early Detection of Dysplasia and Gastric Cancer.

INTRODUCTION: Fundic gland polyps (FGPs) are commonly found in patients with familial adenomatous polyposis (FAP) and are considered benign. Biopsies are not routinely performed, and conventional forceps may be time-consuming and/or yield nonrepresentative histology. The purpose of this study was to evaluate the role of a novel endoscopic polypectomy surveillance (EPS), a large volume cold-snare polypectomy technique of random FGPs, in the incidence of dysplasia and gastric cancer (GC) in FAP. METHODS: This is a retrospective longitudinal cohort of patients with FAP referred to a tertiary care center for duodenal adenoma surveillance and who underwent EPS of FGPs between 2001 and 2019. Demographic, endoscopic, and clinicopathologic information was reviewed. RESULTS: Thirty-five patients with FAP were identified at initial endoscopy by the mean age of 43.4 years (±12.8). One hundred thirteen surveillance endoscopies were performed in total using EPS. Dysplasia of FGPs was present on initial esophagogastroduodenoscopy in 7 patients (20%), and 13 additional patients (46.4%) progressed to low-grade dysplasia. Three patients (15%) who subsequently had progression to GC were found to have signet ring cell cancer within the foci of FGPs through EPS. One patient presented as metastatic GC. Progression from nondysplastic FGP to low-grade dysplasia occurred over 63 months (±46.3) with further progression to GC over 34 months (±8.5). Endoscopic risk factors for cancer were polyps >10 mm in size ( P < 0.001) and carpeting of polyps ( P < 0.001). The 5-year cumulative incidence of developing dysplasia was 35.7%. DISCUSSION: We identified that the incidence of dysplasia and GC is higher than previously reported in patients with FAP. Our study used a novel EPS technique and was able to identify GC within the foci of FGPs. Upper endoscopic guidelines should include a more rigorous sampling method for FGPs, such as EPS, to optimize early detection of dysplasia and GC.

Hyaluronan heterogeneity in pancreatic ductal adenocarcinoma: Primary tumors compared to sites of metastasis.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers with poor survival. The dense desmoplastic stroma in PDAC contributes to treatment resistance. Among the components comprising the tumor stroma, hyaluronan (HA) has been demonstrated to play a critical role in tumor progression and survival. Previous preliminary studies have suggested differences in HA expression in primary and metastatic foci of PDAC. However, the effects of treatment and location of HA expression as a biomarker signature remain unknown; this study sought to compare HA expression in primary and metastatic sites of PDAC. METHODS: Tissue from primary and metastatic PDACs were obtained from Cedars-Sinai Medical Center along with associated clinical data. Tissue slides were stained for H&E, HA, and CD44. Associations between HA levels and the evaluated variables were examined including progression free survival and overall survival. RESULTS: HA score was significantly higher in primary PDACs compared to sites of metastases (p = 0.0148). Within the metastases, HA score was significantly higher in liver metastases compared to metastases at other sites (p = 0.0478). In the treatment-naive liver metastasis cohort, patients with HA high status had decreased progression free survival and overall survival compared to patients with HA low status (p = 0.0032 and p = 0.0478, respectively). CONCLUSIONS: HA score is variable between primary PDAC, PDAC metastatic to the liver, and PDAC metastatic to other sites. Within liver metastases, patients with HA high status had decreased progression free survival and overall survival compared to patients with HA low status. HA levels can serve as a potential biomarker to guide pancreatic cancer treatments and trial design for agents targeting the stroma.

Evaluation of tumor mutational burden in small early hepatocellular carcinoma and progressed hepatocellular carcinoma.

While researchers know that tumor mutational burden (TMB) is low in hepatocellular carcinoma (HCC), prior studies have not investigated TMB in cirrhosis, small early HCC and progressed HCC. HCC (n = 18) and cirrhosis (n = 6) cases were identified. TMB was determined by a 1.7 megabase, 409-gene next-generation sequencing panel. TMB values were defined as the number of nonsynonymous variants per megabase of sequence. There was no significant difference between cirrhosis versus small early HCC or between cohorts when stratified by size, early versus progressed, differentiation or morphology. There was a significant difference between cirrhosis and small early HCC versus progressed HCC (p = 0.045), suggesting TMB may be related to HCC progression. TMB similarities in small early HCC and background cirrhosis suggest TMB is not a useful tool for diagnosing small early HCC. Additional study is needed to address TMB in histological and molecular subsets of HCC.

Applying criteria for hepatocellular neoplasm of uncertain malignant potential reclassifies more than half of hepatocellular adenomas.

OBJECTIVES: Hepatocellular adenoma (HCA) is a benign well-differentiated hepatocellular neoplasm that can be difficult to distinguish from well-differentiated hepatocellular carcinoma (HCC). The term "well-differentiated hepatocellular neoplasm of uncertain malignant potential" (HUMP) has been proposed for neoplasms resembling HCAs, but arising in atypical clinical situations (in females over 50 years old or under 15, in males, with anabolic steroid use, or in some congenital conditions), and/or with atypical pathological features (focal cytological/architectural atypia, ß-catenin activation, or focal reticulin loss) insufficient for an unequivocal diagnosis of HCC. METHODS: This study evaluated HUMP criteria on 42 previously diagnosed HCAs from 33 patients. RESULTS: Twenty-six (62%) masses from 21 patients were classified as HUMPs. Eleven (42%) had focal cytological atypia, and two (8%) had focal architectural atypia. Four (15%) showed focal reticulin loss. Five (19%) showed evidence of ß-catenin activation. Four (12%) HUMP patients were male. CONCLUSIONS: In this series, HUMP did not correlate with an increased rate of synchronous or metachronous HCC compared to HCA. Clinical colleagues may not accept such a high rate of tumors placed in a category of "uncertain malignant potential". Additional study is warranted to refine criteria for designating well-differentiated hepatocellular neoplasms as of uncertain malignant potential.

Lymphogranuloma venereum (LGV) of the anorectum: evaluation of clinicopathological associations and the utility of a novel RNA in-situ hybridisation stain.

AIMS: Recent studies from multiple global regions have reported a resurgence of lymphogranuloma venereum (LGV) proctitis, which is caused by Chlamydia trachomatis (CT). LGV proctitis is histologically indistinguishable from other forms of sexually transmitted proctitis and is difficult to differentiate from inflammatory bowel disease. While immunohistochemical stains are available for syphilis, there is no commonly available stain for the tissue identification of CT. MATERIALS AND METHODS: From 200 positive CT nucleic acid tests (NAT) from anorectal swabs, we identified 12 patients with biopsies collected from the distal colorectum or anus within 90 days of the positive NAT. We collected basic demographic information and tabulated clinical and histological findings. We examined the performance of a novel RNA in-situ hybridisation (ISH) stain targeting CT 23s rRNA on these 12 cases and 10 controls from the anorectum. RESULTS: All 12 patients were male; nine were HIV+, two had concurrent gonococcal infection, one had concurrent syphilis and one had cytomegalovirus co-infection. The majority of biopsies (11 of 12) showed mild or moderate acute inflammation, had a prominent lymphoplasmacytic infiltrate (eight of 11) and lacked marked crypt distortion (10 of 10). The RNA ISH stain was positive in 10 of 12 cases (sensitivity 83%). One case showed equivocal staining. No controls showed definitive positive staining (specificity 100%). One had equivocal staining. CONCLUSION: Our series showed that anorectal LGV had similar histological findings to those of prior STI proctitis series predominantly comprised of syphilis. The novel RNA ISH stain was sensitive and specific and may show utility in differentiating types of STI proctitis.

New Names for Old Tumors.

OBJECTIVES: Previous studies described "clear cell" hepatocellular carcinoma (HCC), although definitions have varied. New clear cell subtypes of HCC have been proposed, including chromophobe (C-HCC), steatohepatitic (SH-HCC), and steatotic (S-HCC), and this study assessed the utility and clinical-pathologic profile of these subtypes. METHODS: Current histologic definitions, including 3 separate proposed definitions for SH-HCC, were applied to tumors previously characterized as clear cell HCC. Histologic and clinical variables were analyzed. RESULTS: Of 66 HCCs, 51 (77%) were classified using modern definitions, including 34 SH-HCCs, 15 S-HCCs, and 2 C-HCCs. Compared with the most permissive SH-HCC definition, the other 2 definitions designated 30 and 25 SH-HCCs (-12% and -26% cases, respectively). Unsurprisingly, S-HCC and SH-HCC were associated with steatotic clear cells (P < .0001). S-HCC was also more typically early type and low grade (P = .0017). The remaining unclassified clear cell HCCs were associated with flocculent (rather than steatotic or optically clear) cytoplasm (P < .0001) but otherwise demonstrated no discrete clinical-pathologic profile. CONCLUSIONS: Current definitions could be used to reclassify the majority of "clear cell" HCCs. The subtypes are significantly correlated with a few variables, suggesting valid differences of the subtypes, although additional study is warranted, particularly to standardize the definition of SH-HCC.

Pancreatic cancer 'mismatch' in Lynch syndrome.

OBJECTIVE: Immune therapy with the PD1 inhibitor pembrolizumab has been approved to treat unresectable/metastatic solid tumours exhibiting mismatch repair (MMR) deficiency. Lynch syndrome (LS), caused by autosomal dominant germline mutations of a MMR gene, predisposes to the development of MMR-deficient cancers. We report a case of MSH2-LS with an MMR-intact pancreatic ductal adenocarcinoma (PDAC) ineligible for treatment with pembrolizumab. DESIGN: Immunohistochemistry of MMR proteins was performed in each malignancy developed in a MSH2-LS patient to determine MMR status. RESULTS: The patient carried a pathogenic MSH2 germline mutation and had a history of LS-type cancers, including endometrial carcinoma, colorectal adenocarcinoma, urothelial carcinoma of the bladder and PDAC. Three malignancies (endometrial, colorectal, urothelial) lacked MSH2 and MSH6 expression, consistent with MSH2-associated tumorigenesis. However, MSH2 and MSH6 expression were intact in the PDAC, suggesting the sporadic occurrence of the pancreatic tumour unrelated to the germline MSH2 mutation. These inconsistent MMR statuses among the tumours rendered the patient ineligible for the immunotherapy pembrolizumab. CONCLUSION: Testing for MMR protein expression is recommended for each tumour in patients with LS, especially pancreatic, as discordant results may have profound effects on treatment opportunities. To our knowledge, this is the first documented case of MMR-intact PDAC in a patient with MSH2-LS.

Stromal hyaluronan accumulation is associated with low tumor grade and nodal metastases in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma is an aggressive malignancy characterized by abundant desmoplastic stroma. Hyaluronan is a prominent stromal component of pancreatic ductal adenocarcinoma and is associated with unique clinical-pathological profiles in other tumor types. The current study aimed to delineate clinical and pathological features associated with hyaluronan accumulation in pancreatic ductal adenocarcinoma using a novel hyaluronan-binding assay currently being used in a clinical trial targeting hyaluronan. Sixty-four formalin-fixed, paraffin-embedded samples of pancreatic ductal adenocarcinomas from 49 patients treated at a single tertiary care hospital were stained. Fifty-two percent of tumors had high levels of hyaluronan. High levels were associated with low tumor grade and lymph node metastases, novel associations not previously seen in pancreatic ductal adenocarcinoma. This study has elucidated a novel clinical-pathological profile in pancreatic ductal adenocarcinomas using a new assay, suggesting hyaluronan may act as a biomarker for a subset of pancreatic tumors that could be targeted by hyaluronan-degrading agents.

Clear Cell Variant of Solid Pseudopapillary Neoplasm of the Pancreas: A Report of a Rare Variant and Review of the Literature.

The clear cell variant of solid pseudopapillary neoplasm (ccSPN) of the pancreas was first described in 2006. In this article, we report a case of this rare variant and review the few published reports. Both the current and previous reports show that ccSPN has several morphologic differences from conventional SPN, including clear vacuoles, fewer pseudopapillary formations, more solid/diffuse architecture, less hemorrhage, and fewer cholesterol clefts. Some of these features peculiar to ccSPN, such as solid/diffuse architecture, have been proposed to suggest aggressive behavior, though reports of ccSPN are rare and often have limited clinical follow-up. ccSPN also appears to occur more frequently in males than conventional SPNs. These clinical and pathologic features lead to unique set of differential diagnostic considerations for ccSPN, including metastatic renal cell carcinoma, perivascular epithelial cell tumor, and clear cell variants of other carcinomas. These unique features, atypical differential, and uncertain prognostic ramifications all make ccSPN an important variant to be aware of and report.