Efficacy and Safety of Cold Snare Endoscopic Mucosal Resection (CS-EMR) for Nonampullary Duodenal Polyps: Systematic Review and Meta-Analysis.

INTRODUCTION: There is an increasing interest in cold snare endoscopic mucosal resection (CS-EMR), and studies have shown its safety and efficacy for colonic polyps. This meta-analysis aims to assess the safety and efficacy of CS-EMR for the removal of duodenal adenomas. METHODS: We conducted a comprehensive literature search of several databases, from inception through February 2023, for studies that addressed outcomes of CS-EMR for nonampullary duodenal adenomas. We used the random-effects model for the statistical analysis. The weighted pooled rates were used to summarize the technical success, polyp recurrence, bleeding, and perforation events. Cochran Q test and I2 statistics adjudicated heterogeneity. RESULTS: Six studies were included in the analysis. In all, 178 duodenal polyps were resected using CS-EMR. The pooled rates were 95.8% (95% CI 89.1-98.5%, I2=21.5%) for technical success and 21.2% (95% CI 8.5-43.6%, I2=78%) for polyp recurrence. With regards to CS-EMR safety, the pooled rates were 4.2% (95% CI 1.6-10.5%, I2=12%) for immediate bleeding, 3.4% (95% CI 1.5-7.6%, I2=0%) for delayed bleeding, 2.8% (95% CI 1.1-6.7%, I2=0%) for perforation, and 2% (95% CL 0.5-7.5%, I2=0%) for post-polypectomy syndrome. Rates were not significantly different for large adenomas. Three studies reported data on CS-EMR and conventional EMR. Compared with conventional EMR, CS-EMR had lower odds of delayed bleeding, OR 0.11 (CI 0.02-0.62, P value 0.012, I2=0%). CONCLUSION: Our findings suggest that CS-EMR is a safe and effective strategy for the resection of nonampullary duodenal adenomas, with an acceptable recurrence rate. Data from larger randomized controlled studies are needed to validate our findings.

Clinical spectrum of cutaneous melanoma morphology.

BACKGROUND: Melanoma can mimic other cutaneous lesions, but the full spectrum and prevalence of these morphologic variants remain largely unknown. OBJECTIVE: To classify nonacral cutaneous melanomas into distinct morphologic clusters and characterize clusters' clinicopathologic features. METHODS: All pathologic melanoma diagnoses (occurring during 2011-2016) were reviewed for routine prebiopsy digital photographs (n = 400). Six dermatologists independently assigned lesions into 1 of 14 diagnostic classes on the basis of morphology. Image consensus clusters were generated by K-means; clinicopathologic features were compared with analysis of variance and χ2. RESULTS: Five morphologic clusters were identified: typical (n = 136), nevus-like (n = 81), amelanotic/nonmelanoma skin cancer (NMSC)-like (n = 70), seborrheic keratosis (SK)-like (n = 68), and lentigo/lentigo maligna (LM)-like (n = 45) melanomas. Nevus-like melanomas were found in younger patients. Nevus-like and lentigo/LM-like melanomas tended to be thinner and more likely identified on routine dermatologic examinations. NMSC-like melanomas were tender, thicker, more mitotically active, and associated with prior NMSC. Typical and SK-like melanomas had similar clinicopathologic features. LIMITATIONS: Cluster subdivision yielded diminished sample sizes. Visual assignment was performed without clinical context. CONCLUSION: When primary cutaneous melanomas were assigned into diagnostic groups and subjected to novel consensus clustering, recurrent morphologic patterns emerged. The spectrum of these morphologies was unexpectedly diverse, which might have implications for visual training and possibly clinical diagnosis.

From cytoskeletal dynamics to organ asymmetry: a nonlinear, regulative pathway underlies left-right patterning.

Consistent left-right (LR) asymmetry is a fundamental aspect of the bodyplan across phyla, and errors of laterality form an important class of human birth defects. Its molecular underpinning was first discovered as a sequential pathway of left- and right-sided gene expression that controlled positioning of the heart and visceral organs. Recent data have revised this picture in two important ways. First, the physical origin of chirality has been identified; cytoskeletal dynamics underlie the asymmetry of single-cell behaviour and patterning of the LR axis. Second, the pathway is not linear: early disruptions that alter the normal sidedness of upstream asymmetric genes do not necessarily induce defects in the laterality of the downstream genes or in organ situs Thus, the LR pathway is a unique example of two fascinating aspects of biology: the interplay of physics and genetics in establishing large-scale anatomy, and regulative (shape-homeostatic) pathways that correct molecular and anatomical errors over time. Here, we review aspects of asymmetry from its intracellular, cytoplasmic origins to the recently uncovered ability of the LR control circuitry to achieve correct gene expression and morphology despite reversals of key 'determinant' genes. We provide novel functional data, in Xenopus laevis, on conserved elements of the cytoskeleton that drive asymmetry, and comparatively analyse it together with previously published results in the field. Our new observations and meta-analysis demonstrate that despite aberrant expression of upstream regulatory genes, embryos can progressively normalize transcriptional cascades and anatomical outcomes. LR patterning can thus serve as a paradigm of how subcellular physics and gene expression cooperate to achieve developmental robustness of a body axis.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.