Faculty Bibliography

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

Inflammation is paramount in pancreatic oncogenesis. We identified a uniquely activated gammadeltaT cell population, which constituted approximately 40% of tumor-infiltrating T cells in human pancreatic ductal adenocarcinoma (PDA). Recruitment and activation of gammadeltaT cells was contingent on diverse chemokine signals. Deletion, depletion, or blockade of gammadeltaT cell recruitment was protective against PDA and resulted in increased infiltration, activation, and Th1 polarization of alphabetaT cells. Although alphabetaT cells were dispensable to outcome in PDA, they became indispensable mediators of tumor protection upon gammadeltaT cell ablation. PDA-infiltrating gammadeltaT cells expressed high levels of exhaustion ligands and thereby negated adaptive anti-tumor immunity. Blockade of PD-L1 in gammadeltaT cells enhanced CD4+ and CD8+ T cell infiltration and immunogenicity and induced tumor protection suggesting that gammadeltaT cells are critical sources of immune-suppressive checkpoint ligands in PDA. We describe gammadeltaT cells as central regulators of effector T cell activation in cancer via novel cross-talk.

PURPOSE: To assess the use of diffusion-weighted imaging (DWI) for differentiating acute from chronic cholecystitis, in comparison with conventional magnetic resonance imaging (MRI) features. MATERIALS AND METHODS: Liver MRI including DWI (b-values 0/500/1000s/mm2 ) was performed at 1.5T