Metastatic renal cell carcinoma presenting as gastric polyps: A case report and review of the literature

AbstractINTRODUCTIONRenal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and is responsible for over 13,000 deaths in the U.S. annually. The fatalities are largely due to distant metastasis, with lung, liver, bone and brain being most commonly affected organs. Gastric metastasis from RCC is a rare event (less than 20 cases reported in the English language literature) and usually presents as a large, solitary mass or ulcer (average size of 4.8cm) resembling primary gastric cancer. Here we report the first case of metastatic RCC presenting as small gastric polyps.PRESENTATION OF CASEThe patient was a 60-year-old African American woman with a history of clear cell RCC (pT1bNX). She underwent esophagogastroduodenoscopy and colonoscopy 5months after nephrectomy due to anemia. Two non-ulcerated, 0.6-cm benign-appearing polyps were found at the greater curvature of the gastric body, which were subsequently removed endoscopically. Unexpectedly, histopathologic examination of the gastric polyps revealed nested collections of vacuolated epithelioid cells in a background of delicate, arborizing vasculature, immediately beneath the congested and hyperplastic foveolar epithelium. A diagnosis of metastatic RCC was rendered after confirming the renal epithelial origin by immunohistochemical stains.DISCUSSIONGastric metastasis from RCC usually presents as a large, solitary mass or ulcer, but it can be subtle and present as multiple, small benign-appearing polyps.CONCLUSIONA careful follow up and thorough endoscopic and histopathologic examinations should be conducted in patients with a history of RCC who present with gastrointestinal manifestations

Micro-Crack Formation and Controlling of Inconel625 Parts Fabricated by Selective Laser Melting

Micro-crack is one of the most serious defects in selective laser melting (SLM), which impair the mechanical properties of the fabricated parts. In this study, Inconel625 superalloy specimens were fabricated by SLM process with progressive alternative scan strategy. The morphology of the cracks, elements distribution were detected by optical microscope (OM), scanning electron microscope (SEM) and electron back scattered diffraction (EBSD). The results showed that a large numbers of micro-cracks occurred at room temperature, with the average length of approximately 100 µm. It was found that crack formation was attribute to the local segregation of Nb and Mo element in the process of rapid solidification, resulting in the generation of low melting temperature eutectic solidification (γ+Laves). Micro-cracks grows along the interface of (γ+Laves) under the thermal stress. Base-plate preheating shows an efficient method to reduce the scales and number of cracks. The residual stress was reduced by more than 50% when preheating at 300℃.Mechanical Engineerin

LoDisc: Learning Global-Local Discriminative Features for Self-Supervised Fine-Grained Visual Recognition

Self-supervised contrastive learning strategy has attracted remarkable attention due to its exceptional ability in representation learning. However, current contrastive learning tends to learn global coarse-grained representations of the image that benefit generic object recognition, whereas such coarse-grained features are insufficient for fine-grained visual recognition. In this paper, we present to incorporate the subtle local fine-grained feature learning into global self-supervised contrastive learning through a pure self-supervised global-local fine-grained contrastive learning framework. Specifically, a novel pretext task called Local Discrimination (LoDisc) is proposed to explicitly supervise self-supervised model's focus towards local pivotal regions which are captured by a simple-but-effective location-wise mask sampling strategy. We show that Local Discrimination pretext task can effectively enhance fine-grained clues in important local regions, and the global-local framework further refines the fine-grained feature representations of images. Extensive experimental results on different fine-grained object recognition tasks demonstrate that the proposed method can lead to a decent improvement in different evaluation settings. Meanwhile, the proposed method is also effective in general object recognition tasks.Comment: 11 pages, submitte

Electronic Structure in Gapped Graphene with Coulomb Potential

In this paper, we numerically study the bound electron states induced by long range Coulomb impurity in gapped graphene and the quasi-bound states in supercritical region based on the lattice model. We present a detailed comparison between our numerical simulations and the prediction of the continuum model which is described by the Dirac equation in (2+1)-dimensional Quantum Electrodynamics (QED). We also use the Fano's formalism to investigate the quasi-bound state development and design an accessible experiments to test the decay of the supercritical vacuum in the gapped graphene.Comment: 5 page, 4 figure