Real-time in vivo histologic examination using a probe-based endocytoscopy system for differentiating duodenal polyps.

Endocytoscopy is an emerging endoscopic imaging modality enabling real-time in vivo visualization of the superficial mucosal layer at a magnification up to 1400fold. This allows analyzing ultrastructural features of a tissue, including the arrangement and density of cells, the nucleus-tocytoplasm ratio, and the microvascular network [1]. Endocytoscopy is based on the principle of contact light microscopy and requires prestaining of the mucosa with either methylene blue or toluidine blue. Previous studies have shown the potential of endocytoscopy for in vivo diagnosis of esophageal squamous cell carcinoma, celiac disease, and colonic polyps. Moreover, recent data suggest the potential of endocytoscopy to differentiate between individual mucosal inflammatory cells during endoscopy [2–4]. Here,we present the case of a 57-year-oldman,whopresentedatour outpatient clinic with mild dyspeptic symptoms and occasional heartburn. Physical examination, medical history, and routine laboratory investigations were unremarkable. Esophagogastroduodenoscopy (EGD) showed an 8-mm polypoid lesion in the deeper part of the duodenum (●" Fig.1). After withdrawal of the endoscope (GIF Q160; Olympus, Tokyo, Japan) we attached a clear cap to the distal end of the scope. After thorough washing of the mucosa with water, targeted chromoendoscopy was used to apply 1% methylene blue over the polypoid lesion. To allow good differentiation ofmucosal cells, thestainwas left in situ for 3 minutes, followed by repeat washing of the mucosa with water. Then a probebased endocytoscopy system (XEC-300, Olympus, Tokyo, Japan) was introduced through the working channel of the endoscope until the top of the endocytoscope touched the polyp’s surface to ensure in vivo tissue imaging. The polypoid duodenal mucosa showed elongation of glands and villi and a slightly serrated appearance. In addition, we observed several small, roundish nuclei, but these were not indicative of malignancy (●" Fig.2). The polyp was resected by snare polypectomy and the in vivo diagnosis of hyperplastic regenerative polyp was confirmed on histopathological analysis, which showed hyperplastic epithelium, elongatedglands, incomplete gastric metaplasia of the surface epithelium, increase in the number of capillaries, and apical fibrosis (mostly due to healing of a prior lesion). A few hyperplastic Brunner’s glands were present in the lower half of the lesion and extending towards the surface, thereby further enhancing the polypoid aspect of the lesion (●" Fig.3). Our case is of interest for several reasons. First, this is the first time an in vivo optical biopsy technique has been used for characterization of a duodenal polyp. Endocytoscopy readily identified mucosal alterations typical of a hyperplastic regenerative duodenal polyp. Second, several types of polyps can occur in the duodenum, including non-neoplastic (e.g., ectopic gastric mucosa, inflammatory polyps, Brunner’s gland hyperplasia) and neoplastic (e.g., adenoma, gastrointestinal stromal tumor) polyps. The reported frequency of occurrence of hyperplastic duodenal polyps is very low. To the best of our Fig.1 Conventional white-light endoscopy in a 57-year-old-man with mild dyspeptic symptoms and occasional heartburn. There is a large polypoid lesion in the deeper part of the duodenum.