Neuroendocrine Neoplasms of the Pancreas: Diagnostic Challenges and Practical Approach.

Most pancreatic neuroendocrine neoplasms are slow-growing, and the patients may survive for many years, even after distant metastasis. The tumors usually display characteristic organoid growth patterns with typical neuroendocrine morphology. A smaller portion of the tumors follows a more precipitous clinical course. The classification has evolved from morphologic patterns to the current World Health Organization classification, with better-defined grading and prognostic criteria. Recent advances in molecular pathology have further improved our understanding of the pathogenesis of these tumors. Various issues and challenges remain, including the correct recognition of a neuroendocrine neoplasm, accurate classification and grading of the tumor, and differentiation from mimickers. This review focuses on the practical aspects during the workup of pancreatic neuroendocrine neoplasms and attempts to provide a general framework to help achieve an accurate diagnosis, classification, and grading.

Histological features of Clostridioides difficile colitis in patients with inflammatory bowel disease.

AIMS: Patients with inflammatory bowel disease (IBD) are at increased risk for Clostridioides difficile infection, although clinically important infections can be difficult to recognise. C. difficile infection does not produce pseudomembranes when it occurs in IBD patients. These individuals may also be colonised by the organism, in which case diarrhoeal symptoms are not necessarily attributed to C. difficile. We performed this study to determine whether any features distinguished C. difficile-associated colitis from an IBD flare. METHODS AND RESULTS: We reviewed the clinical, endoscopic and biopsy findings from 50 patients with established IBD and worsening diarrhoea, including 22 with concurrent positive C. difficile stool toxin polymerase chain reaction (PCR) assays and 28 with negative C. difficile assay results. We found that C. difficile-infected patients had symptoms and endoscopic findings that were indistinguishable from active IBD. Although most biopsy samples from patients with C. difficile infection showed chronic active colitis indistinguishable from IBD, some displayed neutrophilic infiltrates unaccompanied by plasma cell-rich inflammation involving superficial (41%) and crypt (18%) epithelium as well as neutrophilic infiltrates within lamina propria distant from foci of cryptitis (32%). All three of these features were significantly more common among infected than uninfected patients (4, 0 and 4%; P = 0.002, P = 0.03 and P = 0.02, respectively). CONCLUSIONS: Although colonic biopsies from IBD patients with C. difficile infection usually lack features that aid distinction from colitic flares, some cases show an acute colitis pattern not seen in IBD alone. When identified in biopsies from symptomatic IBD patients, these changes should alert pathologists to the possibility of this clinically important infection.

Virtual biopsies: Proof of concept for a novel quantitative approach to liver biopsy adequacy and pathology education.

OBJECTIVES: To quantitatively measure liver biopsy adequacy requirements and the effect of a teaching intervention that uses a virtual biopsy platform. METHODS: A library of virtual liver biopsies was created using digital whole-slide, trichrome-stained tissue sections from liver resection material and QuPath image analysis software. Blinded participants staged fibrosis on the virtual biopsies before and after a teaching intervention. RESULTS: This platform both modeled adequacy requirements for cirrhosis diagnosis on biopsy material and measured the effect of a teaching intervention on participant performance. Using this platform, diagnostic accuracy for cirrhosis could be modeled according to the function y = λ(1 ‒ e‒x/γ). The platform demonstrated that the relationship between biopsy size and diagnostic accuracy was statistically significant and that biopsies smaller than 6 mm long and 0.8 mm wide were insufficient to diagnosis cirrhosis. The platform also measured improvement in fibrosis staging accuracy among participants following a teaching intervention. CONCLUSIONS: These results provide proof of concept for a virtual biopsy method by which outstanding questions in anatomic pathology can be addressed quantitatively using open source software. Future work is needed to validate these findings in clinical practice.