More than 20 years have passed since the term “laterally spreading tumor (LST)” was originally proposed by Kudo, et al., and its clinical significance has been recognized worldwide. An LST is defined as a colorectal tumor larger than 10 mm in diameter that tends to extend laterally/horizontally, rather than vertically in the colorectum. In July 2013 the term “LST” was described in the Japanese Classification of Colorectal Carcinoma, 8th Edition. The definition of “LST” is an appellation for superficially spreading tumors and not for macroscopic classification. LSTs are divided into two subtypes based on their detailed endoscopic appearance : granular type (LST-G), which has even or uneven nodules on the surface, and non-granular type (LST-NG), which has a smooth surface. Furthermore, each type has two subtypes : LST-G consists of a “homogeneous type” and a “nodular mixed type”, while LST-NG consists of a “flat elevated type” and “pseudodepressed type”. The subclassification provides clinically important information in determining the appropriate therapeutic strategy. However, in some cases, the diagnoses of the subclassifications (especially for LST-G subclassification) are not consistent among endoscopists or institutions. In this review, we clarify the current issues regarding subclassification of LSTs and propose objective subclassification criteria of LST-Gs based on the size of granules or nodules in relation to their clinical significance.

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A 62-year-old man presented with a liver disorder 24 months after distal gastrectomy with a Roux-en-Y reconstruction for gastric cancer. CT imaging showed marked dilatation of the afferent loop, and he was diagnosed with afferent loop syndrome. Membranous anastomotic stenosis at the site of Roux-en-Y jejunojejunostomy, which had been reconstructed by the stapling technique with a circular stapler at the time of gastrectomy, could be identified by double-balloon endoscopy. Subsequently, the anastomotic stenosis was successfully resolved by endoscopic balloon dilatation. A rare case of afferent loop syndrome due to anastomotic stenosis after Roux-en-Y reconstruction by the stapling technique is described.

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A 68-year-old man underwent colonoscopy to investigate his chief complaint of hematochezia. Colonoscopy revealed a laterally spreading tumor (LST) in the ascending colon and colon cancer in the rectum. One month later, colonoscopy prior to undergoing endoscopic submucosal dissection (ESD) of the LST revealed a morphological change of the LST to an elevated lesion and that an Anisakis penetrated the center of the LST. We attempted ESD, but fibrous tissue made dissection difficult. We performed laparoscopic ileocecal resection for the LST and rectectomy for rectal cancer. The histopathological diagnosis was an adenoma of the ascending colon with eosinophilic infiltration. We report a rare case of colonic adenoma with a change in morphology of the tumor by an Anisakis.

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A 62-year-old man was referred to our hospital for further investigation of positive results on fecal occult blood screening test. Colonoscopy showed a submucosal tumor (SMT) of 35 mm in diameter in the ascending colon. FDG-PET revealed abnormal uptake in the ascending colon. Boring biopsy under colonoscopy of the SMT did not provide a precise diagnosis. Therefore, we planned endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) biopsy for the SMT in the ascending colon. After insertion of a colonoscope, insertion of a convex-type EUS was possible using a sliding tube and guidewire. EUS-FNA was performed, and the SMT was diagnosed as a schwannoma. Our result suggests that EUS-FNA at the ascending colon is feasible and effective for obtaining a precise diagnosis.

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[Background and Objective] The influence of differences in the shape of forceps on tissue preparations and histological diagnosis is unclear. These were investigated in atypical epithelial samples that were difficult to histologically distinguish as benign or malignant. [Subjects and Methods] Thirty-three and 29 samples of atypical epithelium biopsied using alligator or standard forceps, respectively, which were difficult to diagnose as benign or malignant were investigated. The quality of tissue preparations was investigated based on the area, crushing, and direction, and the influence on the diagnosis was studied by comparing the histological diagnosis of the samples and actual diagnosis of the patients during their observation course. [Results] The tissue area of the samples collected using alligator forceps was larger with less crushed tissue, the direction was retained, and the number of samples that were difficult to diagnose on the first histological examination was smaller. [Conclusion] The difference in the shape of biopsy forceps may influence the quality of tissue preparations and histological diagnosis.

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According to the World Health Organization (WHO) 2010 classification, neuroendocrine tumors (NETs), especially WHO grade G1, correspond to neoplasms formerly termed as ‘carcinoid tumor’. Duodenal NETs are rare tumors, and not only the knowledge of their endoscopic and physiologic characteristics but also an accurate endoscopic technique are required for precise diagnosis. Regarding the treatment strategy for duodenal NETs, surgical resection is recommended for gastrinomas and ampullary NETs, while the therapeutic approach for non-ampullary NETs depends on its size. However, currently there is no standardized treatment strategy for NETs ≤20 mm in diameter. In the present paper, we describe the optimal endoscopic technique, key diagnostic points, and treatment for duodenal NETs as well as summarize the current knowledge on NETs.

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Background : Certain tumor characteristics may pose challenges when endoscopically determining the horizontal extent of early gastric cancers (EGC). In the present study, clinicopathological features related to inaccurate endoscopic evaluation of horizontal extent of intestinal-type EGC were analyzed.
Patients and Methods : We analyzed 431 lesions with intestinal-type EGC treated by endoscopic submucosal dissection (ESD) at our hospital. We focused on whether pretreatment demarcation was accurate by comparing positional relationships between marking dots and tumor edges in resected specimens, and factors related to inaccurate evaluation were analyzed. Gender, age, tumor size, location, circumference, depth, ulceration, macroscopic type, presence of a flat (0-IIb) component, predominant histological type, mixture of diffuse-type adenocarcinoma, mixed histology, and use of magnification endoscopy with narrow band imaging were analyzed. Reasons for inaccurate evaluation were also investigated by re-examining endoscopic images and prepared histological slides.
Results : Rate of inaccurate evaluation of horizontal extent was 7.4% (32/431 lesions). Multivariate analysis revealed the following significant independent variables contributing to inaccurate endoscopic evaluation : presence of a flat component, large size, and predominant histological findings of moderately differentiated adenocarcinoma. Re-examination of prepared histological slides of inaccurately evaluated cases revealed a marginal flat spreading area in 28 of the 32 lesions (87.5%). In 14 of the 32 lesions (43.8%), tumor margins were composed of moderately differentiated adenocarcinoma.
Conclusions : For lesions with a flat component, large lesions, and moderately differentiated adenocarcinoma, determination of the horizontal extent can be challenging in EGC indicated for ESD, even with the best available endoscopic tools.

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