Resect and discard approach to colon polyps: real-world applicability among academic and community gastroenterologists.

BACKGROUND: "Resect and discard" (RD) is a new paradigm for management of diminutive polyps. AIM: To compare concordance of surveillance interval recommendations and diagnostic performance between RD and standard of care in a hospital outpatient department with both academic and community gastroenterologists. METHODS: Prospective, observational study conducted at a single outpatient endoscopy center over 12 months. Patients with diminutive polyps on screening or surveillance colonoscopy were included. Histology predictions for all diminutive polyps (≤5 mm) were made based on endoscopic imaging. Concordance of recommended surveillance intervals and diagnostic performance of histology predictions were compared to histopathological review. RESULTS: A total of 606 diminutive polyps were found in 315 patients (mean age 62.4 years, 49 % female). Histological prediction was made in 95.7 % of polyps (97.4 % of patients), with high confidence in 74.3 %. The concordance for surveillance intervals was 82.1 % compared to histopathological review and was similar between community and academic gastroenterologists (80.2 vs. 76.3 %, p = 0.38). Overall, sensitivity, specificity, and accuracy of histological predictions made with high confidence were 0.81, 0.36, and 77.1 %. Predictions made with narrow-band imaging (NBI) had lower accuracy (73.9 % with NBI vs. 82.5 % with high-definition white light (HWDL) only, p = 0.017) as well as lower prediction confidence (score of 7.6 with NBI vs. 8.6 with HDWL only, p < 0.001). CONCLUSIONS: Our surveillance interval concordance was below the 90 % threshold deemed acceptable by the ASGE Preservation and Incorporation of Valuable Endoscopic Innovations statement. Diagnostic performance using optical imaging to predict histology was equal between community and academic endoscopists.

Hints to the diagnosis of mixed acinar-endocrine carcinoma on pancreatic fine-needle aspiration: avoiding a potential diagnostic pitfall.

BACKGROUND: Mixed acinar-endocrine carcinoma (MAEC) is a rare mixed tumor of the pancreas defined by both acinar and endocrine cell differentiation. CASE: We present 2 cases of MAEC initially diagnosed as pancreatic endocrine neoplasm on fine-needle aspiration. Both patients were male, aged 51 and 75 years, and presented with 16-mm and 6-mm pancreatic masses, respectively. Aspirates showed loose aggregates and dispersed single plasmacytoid cells with moderate nuclear size variation, slightly irregular nuclear contours, fine to coarsely granular chromatin, occasional prominent nucleoli, and scant to moderate finely granular cytoplasm. Rare mitotic figures and pyknotic forms were noted in one of the cases. Endocrine differentiation was confirmed by immunocytochemistry which led to an initial diagnosis of pancreatic endocrine neoplasm. Trypsin and lipase immunocytochemistry were later obtained, confirming a component of acinar cell differentiation. Findings were confirmed on surgical excision. CONCLUSION: Because of their potentially more aggressive clinical course and different therapeutic implications, MAECs are an important consideration in the differential diagnosis of pancreatic neoplasms. Certain cytomorphologic features and immunocytochemical markers of acinar cell differentiation may be helpful in raising the possibility of MAEC on cytology.

Hyperplastic (serrated) polyps of the colorectum: relationship of CpG island methylator phenotype and K-ras mutation to location and histologic subtype.

We investigated the frequency of promoter region CpG island methylation (CIM) of hMLH1, MGMT, MINT1, MINT2, and p16 and K-ras mutations in a total of 79 hyperplastic (serrated) polyps (HPs) from 75 patients and correlated the molecular profiles to polyp location in the colorectum, histologic variation, and other factors. Methylation-specific PCR (MS-PCR) was used to assay CIM status. HPs that showed CIM of one or more or two or more of the genes assayed were classified as CpG island methylator phenotype (CIMP) and CIMP-high (CIMP-H), respectively. PCR restriction fragment length polymorphism was used to assay K-ras codon 12 and 13 mutations. Logistic regression indicated a statistically significant trend for increasing odds for CIMP (P = 0.002) and CIMP-H (P < 0.001) according to proximity to the cecum or distance from the rectum. Conversely, K-ras codon 12 mutation was present in 13 of 40 (32.5%) distally located HPs compared with 2 of 39 (5.1%) proximal HPs (P = 0.006). Histologic subtype distribution varied by proximal and distal locations. Frequency of CIMP in serrated polyps with abnormal proliferation (SPAPs), differed significantly from goblet cell serrated polyps (GCSPs) (24 of 26, 92.3% vs. 6 of 13, 46.2%) (P = 0.003) and microvesicular serrated polyps (MVSPs) (26 of 38, 68.4%) (P = 0.03). Frequency of K-ras mutation in GCSPs (7 of 13, 54%) differed from that of MVSPs (6 of 38, 16%) (P = 0.01) and SPAPs (2 of 26, 8%) (P = 0.003). Location in the colorectum and histologic subtype were major determinants of the molecular profile of HPs. The molecular findings of CIMP and K-ras mutations appear to encompass most if not all HPs; CIMP profiles suggest that SPAP is the most advanced morphologic variant. We postulate that MVSP and GCSP may be precursor lesions that, if proximally located or larger, can progress to SPAP. Frequent K-ras mutations and infrequent CIMP distinguish the distal GCSP variant.