Faculty Bibliography

Background: Russell Body Gastritis (RBG) is considered to be a rare histologic finding that has an unclear pathogenesis and an unpredictable clinical outcome. We sought to clarify the frequency and significance of RBG by assessing their associated histology and relationship with the local microbiome. Design: We reviewed all 220 gastric biopsies over a 2-month period at 1 institution for the presence and density of Russell bodies (RB). In biopsies with RB, the quantity of RB was manually counted using light microscopy at 200x magnification in every biopsy level (3068 sections) and the sectional area was estimated using a 1x1 mm grid overlay. RB density was calculated by dividing the total quantity of RB in all sections by the total sectional area. 48 additional patients, which corresponded to an extra 100 histologic biopsies, were consented at the same visit for an extra gastric biopsy for 16S rRNA sequencing, and these microbiome profiles were correlated with the highest RB density per patient. Results: Russell bodies (RB) were frequent in gastric biopsies (43% of all gastritides) and the RB density significantly increased with more severe gastritides (p<0.001, n=320). The gastric microbiome globally differed in beta diversity between RB-positive and RB-negative cases by unweighted and weighted principal component analysis (p=0.03, p=0.007, n=48, respectively). In particular, Helicobacter and Streptococcus were significantly enriched in gastritis with RB and their abundances correlated with RB density (p=0.0002, r=0.51; p=0.009, r=0.37, n=48, respectively). Protonpump inhibitor (PPI) use reduced RB density per unit abundance of Streptococcus (p=0.0021, n=48). H. pylori abundance significantly correlated with RB density and two Streptococcus species (an unclassified Streptococcal species and S. anginosus) significantly correlated with RB density in H. pylori-negative gastritis (p=0.009, n=36, r=0.36; p=0.0025, n=36, r=0.51, respectively). 7 H. pylorinegative patients were followed for 1 year and variation in Streptococcus abundance reflected RB density (p=0.085, n=7). Conclusions: RB are common within the inflamed gastric mucosa and gastritis with RB is associated with Helicobacter and Streptococcus enrichment and consequent global shifts in the gastric microbiome. PPI dampens RB production, presumably through anti-inflammatory effects. Gastritis with RB might represent a reactive humoral response to bacteria within the gastric microbiome. Streptococcus species may influence chronic gastritis

Cytologic diagnosis of extra-adrenal paraganglioma presenting as a peripancreatic mass is challenging with a high error rate due to its rarity. We report two cases of peripancreatic masses identified by radiology. Endoscopic ultrasound-guided fine needle aspiration (FNA) of the masses showed a moderately cellular tumor composed of small to medium sized neoplastic cells with round to oval nuclei, arranged singly and in loose clusters. Focal rosette-like structures were present. The cells were positive for neuroendocrine markers (synaptophysin and chromogranin). A diagnosis of a neoplasm with neuroendocrine differentiation and neuroendocrine tumor was made respectively on FNA for each case. The subsequent surgical resection of the tumors revealed peripancreatic paraganglioma. Although paraganglioma has been reported in the literature, the detailed comparison of perpancreatic paraganglioma versus pancreatic/gastrointestinal neuroendocrine tumor is still lacking. Therefore using these two cases with literature review, we wish to illustrate the differential diagnosis between these two entities based on cytomorphology and immunohistochemical study.

Regulatory T (Treg) cell infiltration constitutes a prominent feature of pancreatic ductal adenocarcinoma (PDA). However, the immunomodulatory function of Treg cells in PDA is poorly understood. Here, we demonstrate that Treg cell ablation is sufficient to evoke effective anti-tumor immune response in early and advanced pancreatic tumorigenesis in mice. This response is dependent on interferon-gamma (IFN-gamma)-producing cytotoxic CD8+ T cells. We show that Treg cells engage in extended interactions with tumor-associated CD11c+ dendritic cells (DCs) and restrain their immunogenic function by suppressing the expression of costimulatory ligands necessary for CD8+ T cell activation. Consequently, tumor-associated CD8+ T cells fail to display effector activities when Treg cell ablation is combined with DC depletion. We propose that tumor-infiltrating Treg cells can promote immune tolerance by suppressing tumor-associated DC immunogenicity. The therapeutic manipulation of this axis might provide an effective approach for the targeting of PDA.

PURPOSE: To evaluate whole-lesion ADC histogram metrics for assessing the malignant potential of pancreatic intraductal papillary mucinous neoplasms (IPMNs), including in comparison with conventional MRI features. METHODS: Eighteen branch-duct IPMNs underwent MRI with DWI prior to resection (n = 16) or FNA (n = 2). A blinded radiologist placed 3D volumes-of-interest on the entire IPMN on the ADC map, from which whole-lesion histogram metrics were generated. The reader also assessed IPMN size, mural nodularity, and adjacent main-duct dilation. Benign (low-to-intermediate grade dysplasia; n = 10) and malignant (high-grade dysplasia or invasive adenocarcinoma; n = 8) IPMNs were compared. RESULTS: Whole-lesion ADC histogram metrics demonstrating significant differences between benign and malignant IPMNs were: entropy (5.1 +/- 0.2 vs. 5.4 +/- 0.2; p = 0.01, AUC = 86%); mean of the bottom 10th percentile (2.2 +/- 0.4 vs. 1.6 +/- 0.7; p = 0.03; AUC = 81%); and mean of the 10-25th percentile (2.8 +/- 0.4 vs. 2.3 +/- 0.6; p = 0.04; AUC = 79%). The overall mean ADC, skewness, and kurtosis were not significantly different between groups (p >/= 0.06; AUC = 50-78%). For entropy (highest performing histogram metric), an optimal threshold of >5.3 achieved a sensitivity of 100%, a specificity of 70%, and an accuracy of 83% for predicting malignancy. No significant difference (p = 0.18-0.64) was observed between benign and malignant IPMNs for cyst size >/=3 cm, adjacent main-duct dilatation, or mural nodule. At multivariable analysis of entropy in combination with all other ADC histogram and conventional MRI features, entropy was the only significant independent predictor of malignancy (p = 0.004). CONCLUSION: Although requiring larger studies, ADC entropy obtained from 3D whole-lesion histogram analysis may serve as a biomarker for identifying the malignant potential of IPMNs, independent of conventional MRI features.

BACKGROUND: The management of ectopic pancreas is not well defined. This study aims to determine the prevalence of symptomatic ectopic pancreas and identify those who may benefit from treatment, with a particular focus on robotically assisted surgical management. METHODS: Our institutional pathology database was queried to identify a cohort of ectopic pancreas specimens. Additional clinical data regarding clinical symptomatology, diagnostic studies, and treatment were obtained through chart review. RESULTS: Nineteen cases of ectopic pancreas were found incidentally during surgery for another condition or found incidentally in a pathologic specimen (65.5%). Eleven patients (37.9%) reported prior symptoms, notably abdominal pain and/or gastrointestinal bleeding. The most common locations for ectopic pancreas were the duodenum and small bowel (31% and 27.6%, respectively). Three out of 29 cases (10.3%) had no symptoms, but had evidence of preneoplastic changes on pathology, while one harbored pancreatic cancer. Over the years, treatment of ectopic pancreas has shifted from open to laparoscopic and more recently to robotic surgery. CONCLUSIONS: Our experience is in line with existing evidence supporting surgical treatment of symptomatic or complicated ectopic pancreas. In the current era, minimally invasive and robotic surgery can be used safely and successfully for treatment of ectopic pancreas.

A man aged 83 years with vague perirectal symptoms had a delayed diagnosis of Paget's disease of the anus. A lack of thorough digital rectal examination failed to diagnose a mixed adenonueroendocrine tumour of the rectum in a timely matter.

Pancreatic ductal adenocarcinoma (PDA) is marked by an abundant fibroinflammatory microenvironment. Regulatory T (Treg) cell infiltration constitutes a prominent feature of PDA. However, the immunomodulatory function of Treg cells in PDA remains poorly understood. Using orthotopic and autochthonous mouse models of PDA we have found that Treg cell ablation is sufficient to evoke effective anti-tumor immune response in early and advanced pancreatic neoplasia. This response is dependent on IFN-gamma producing cytotoxic CD8 T cells. We show that Treg cells engage in extended interactions with tumor-associated CD11c dendritic cells (DCs) and restrain their immunogenic function by suppressing the expression of costimulatory ligands necessary for CD8 T cell activation. Consequently, tumor-associated CD8 T cells fail to display effector activities when Treg cell ablation is combined with DC depletion. We propose that tumor-infiltrating Treg cells promote immune-tolerance by suppressing DC immunogenicity. Therapeutic manipulation this axis might provide an effective approach for the targeting of PDA