15:20:14 – Normal gastrointestinal tract and variations on endoscopy

Abbreviations

ATZ

anal transition zone

CD

Crohn’s disease

GI

gastrointestinal

IBD

inflammatory bowel disease

ICV

ileocecal valve

NSAID

non-steroidal anti-inflammatory drugs

PSC

primary sclerosing cholangitis

SCAD

segmental colitis-associated diverticulosis

UC

ulcerative colitis

Introduction

Crohn’s disease (CD) can affect any part of the gastrointestinal (GI) tract, while classic ulcerative colitis (UC) only involves the colon and rectum. Distinction between inflammatory bowel disease (IBD) and other inflammatory, medication-related, neoplastic, and organ transplantation–related disease conditions is discussed in separate chapters. The identification of normal endoscopic features of the esophagus, stomach, small and large intestines, and anorectum is critical for the diagnosis and differential diagnosis of IBD. In addition, there are “normal variations” in endoscopy of the GI tract. Some of these variations can mimic IBD, IBD-associated complications, and other inflammatory or neoplastic conditions.

Esophagus

The inner layer of the esophagus is covered with whitish squamous cells, in contrast to the salmon-color columnar epithelia in the stomach. The longitudinal vascular pattern is visible, especially in the distal esophagus, close to the esophagogastric junction ( Fig. 3.1 A). A congenital cervical inlet patch is occasionally found in the proximal esophagus ( Fig. 3.1 B). The cervical inlet patch consists of the ectopic gastric mucosa. Acid secretion from ectopic gastric mucosa may lead to esophagitis, ulcer, web, or stricture, mimicking CD of the esophagus.

Glycogenic acanthosis in the esophagus is characterized by multifocal plaques of hyperplastic squamous epithelium with intracellular glycogen deposits. Glycogenic acanthosis should be differentiated from Candida esophagitis ( Fig. 3.1C and D ).

Linear white specks are occasionally seen in the normal esophagus ( Fig. 3.2 A), which should be differentiated from white plaques in those with Candida esophagitis. Patients with esophageal spasms, a functional disorder of the esophagus, may present with linear furrows and esophageal rings ( Fig. 3.2 B), resembling that seen in eosinophilic esophagitis ( Fig. 3.2C and D ). The distinction can be made by histologic evaluation.

An image with four labeled endoscopic views showing normal esophagus, Crohn’s-related changes, and features of eosinophilic esophagitis.” The image presents four labeled endoscopic and histologic sections of the esophagus (A–D). Section A shows an esophagus with small linear white specks, highlighted by a green arrow; these specks have no clinical significance and represent a normal finding. Section B depicts pseudolinear furrows in the esophagus of a patient with Crohn’s disease, marked with a yellow arrow, which can mimic eosinophilic esophagitis. Section C demonstrates classic features of eosinophilic esophagitis, including esophageal rings, prominent linear furrows, erosive distal esophageal erosions, and a visible Schatzki ring. Section D shows eosinophilic infiltration within esophageal tissue, marked by a blue arrow, confirming the histological basis of eosinophilic esophagitis. The accompanying caption states: ‘Fig. 3.2. Normal esophagus and eosinophilic esophagitis. (A) Linear white specks (green arrow) with no clinical significance. (B) Pseudolinear furrows (yellow arrow) in a patient with Crohn’s disease, resembling eosinophilic esophagitis. (C) Eosinophilic esophagitis with rings and linear furrows and erosive distal esophageal erosions and Schatzki ring. (D) Eosinophilic infiltration in eosinophilic esophagitis.’ Together, these views contrast normal esophageal findings with pathological changes in Crohn’s disease and eosinophilic esophagitis, integrating both endoscopic and microscopic perspectives. — Figure 3.2

Stomach

IBD rarely involves the stomach. One of the endoscopic features of CD of the stomach is the presence of “bamboo joints” thatwas initially described by Japanese investigators, as shown in Fig. 4.4 in Chapter 4, Crohn’s disease: inflammatory type . Patients with normal stomachs may have a similar endoscopic appearance ( Fig. 3.3 A). Therefore histologic evaluation is critical.

With the extensive use of proton pump inhibitors in the general population, fundic gland polyps are commonly seen in the stomach ( Fig. 3.3 B). However, the presence of fundic gland polyps may reflect the body’s compensatory reaction to various stimuli, such as short-gut syndrome in CD ( Fig. 3.3 C). Antral gastritis in IBD is also common, which is not necessarily a part of the disease ( Fig. 3.3 D), with etiologies such as Helicobacter pylori infection and the use of nonsteroidal anti-inflammatory drugs .

Duodenum

The duodenum is a common location of CD of the upper GI tract. CD of the duodenum may present with nonulcerative inflammation, ulcers, or strictures. The distinction between the inflammatory phenotype of CD and “normal” variations of the duodenum sometimes is difficult on endoscopy.

The duNodenum bulb in healthy individuals can have various appearances. The bulbar mucosa can be granular or nodular in a non-disease setting. Granularity and nodularity of the bulbar mucosa mainly consist of Bruner’s glands or Brunner’s gland hyperplasia ( Figs. 3.4 A and B and 3.5 ). Subtle erosions can hide between nodular bulb mucosa ( Fig. 3.4 C and D)

An image with four endoscopic views of the duodenal bulb under white light and narrow-band imaging, showing normal mucosa and Crohn’s-related erosions. The images show endoscopic views of the duodenal bulb labeled A–D. Image A under white light reveals normal granular and nodular mucosa with short villi and smooth texture. Image B, using narrow-band imaging, enhances the mucosal pattern with greater contrast. Image C, also under white light, shows subtle erosions suggestive of Crohn’s disease with visible mucosal damage. Image D, under narrow-band imaging, highlights these erosions more distinctly, with greenish hues marking inflammatory changes. — Figure 3.4

An image set showing duodenal nodular mucosa from Brunner’s gland hyperplasia and immunofluorescence highlighting lysozyme and defensin markers. “The images present endoscopic and microscopic views illustrating Brunner’s gland hyperplasia in the duodenum. Images A and B show the duodenal bulb with a nodular mucosa localized in the anterior wall, characterized by a thickened and irregular surface typical of hyperplastic changes. These nodular features reflect the localized overgrowth of Brunner’s glands. Image C uses immunofluorescence to visualize the same condition at a cellular level, with lysozyme marked in green and human-defensin-5 highlighted in red. The green fluorescent staining corresponds to Brunner’s gland cells, while the red fluorescence identifies Paneth cells in the intestinal epithelium. The dark background creates sharp contrast, enhancing the visibility of the markers and allowing the viewer to distinguish the different cell populations clearly. Although the magnification level is not specified, the fine detail of the staining suggests high-power imaging was used to examine these microscopic features, providing both structural and functional insight into the pathology of Brunner’s gland hyperplasia. — Figure 3.5

The duodenum cap is located in the junction between the bulb and the second portion of the duodenum, which is a common place for strictures in CD of the upper GI tract ( Fig. 3.6 ). Positioning the endoscope’s tip at the cap or duodenum sweep can be challenging.

An image with four endoscopic duodenum views showing normal areas and Crohn’s-related strictures. The image contains four labeled endoscopic views of the duodenum (A–D). Image A shows a section of the duodenum with a green arrow pointing to the cap between the bulb and second portion. Image B displays another view of the cap with a green arrow highlighting a different area. Image C shows a yellow arrow pointing to a Crohn’s disease–related stricture in the duodenum. Image D depicts a subtle Crohn’s stricture that had been missed in earlier endoscopic examinations. The caption provides context for each view. — Figure 3.6

The second to fourth portions of the normal duodenum are characterized by the folds, villi, and occasionally lacteals, which are different from the bulbar mucosa. The villi can be highlighted with image-enhanced endoscopy ( Fig. 3.7 ) Lacteals may present with punctate white spots which mostly represent some degree of intestinal lymphangiectasia ( Fig. 3.8 A and B,) . Diffuse white duodenum mucosa, however, may be associated with nonspecific inflammation, infections (such as Whipple’s disease), or lymphoma . In between the white mucosa, there may be erythematous mucosa with short villi resulting from mucin depletion from IBD, the use of non-steroidal anti-inflammatory drugs ( Fig. 3.8 C and D). Nodules or polypoid lesions can be seen in the duodenum in the healthy or diseased ( Fig. 3.9 )

An image set showing normal duodenal mucosa, narrow-band imaging of villi, and a stained histologic section highlighting villous structure. The images present a comparative view of the duodenal mucosa using endoscopic and histologic techniques. Image A shows the normal mucosa of the second portion of the duodenum, characterized by smooth reddish tissue with well-defined villi typical of a healthy mucosal surface. Image B employs narrow-band imaging, which enhances visualization of the mucosal villi, making their fine details and surface texture more distinct. This allows for better assessment of villous patterns and surface structure. Image C presents a histologic section of duodenal villi under high magnification, stained to emphasize the intricate architecture and cellular organization. The staining provides contrast between the villi and surrounding connective tissue, highlighting the arrangement of epithelial layers and supporting stroma. Although the magnification power is not specified, the clarity and detail visible suggest that a high-power microscopic view was employed to capture the structural complexity of the duodenal villi. — Figure 3.7

An image with four duodenal views showing diffuse white mucosa, lymphangiectasia, patchy erythema, and mucin depletion. Figure 3.8 shows endoscopic images of normal and abnormal mucosa in the second portion of the duodenum. Images A and B depict a diffuse or spotted white appearance of the duodenum due to lacteals, with lymphangiectasia visible as a white nodule. Image C shows patchy erythema caused by mucin depletion of the epithelium. Image D demonstrates further mucin depletion of the duodenal epithelium. These examples highlight structural and mucosal changes, with images provided courtesy of Mabel Ko, MD, Columbia University. — Figure 3.8

An image with four duodenal views showing gastric heterotopia, Crohn’s-related duodenitis, diffuse polyps in polyposis, and duodenitis with mucosal nodularity. The image set presents four labeled endoscopic views (A–D) of duodenal mucosal changes in different clinical contexts. Image A demonstrates gastric (fundic) heterotopia with multiple smooth, rounded nodules in the second part of the duodenum of a healthy individual, set against a reddish background. Image B depicts duodenitis in a patient with Crohn’s disease, showing erythema and irregular nodules surrounded by inflamed reddish tissue. Image C illustrates diffuse flat polyps across the mucosal surface of the duodenum in a patient with familial adenomatous polyposis; the polyps appear widespread and flat, with a reddish background. Image D presents diffuse duodenitis with prominent mucosal nodularity in a patient with ulcerative colitis and ileal pouch-anal anastomosis, characterized by an inflamed, reddish surface. Together, these images highlight different duodenal presentations ranging from benign heterotopia to inflammatory and hereditary polyposis-related changes. — Figure 3.9

A proper evaluation of the size of the lumen and luminal contents of the duodenum may yield some diagnostic clues. Dilated lumen of the duodenum may result from distal obstruction, small bowel bacterial overgrowth, and gastroenteritis. A pool of luminal secretion with dilated duodenum or other parts of the small intestine can be a sign of small bowel bacterial overgrowth ( Fig. 3.10 ).

Duodenum papilla may present in different shapes and sizes ( Fig. 3.11 A and B). The papilla and surrounding areas are common locations for familial adenomatous polyposis ( Fig. 3.6 B). Patients with ulcerative colitis, or primary sclerosing cholangitis (PSC) or IgG4-associated systemic disorders may present with diffuse duodenitis or mucinous discharge from intraductal papillary mucinous neoplasm ( Fig. 3.11 C-new). Ampullary adenomas can occur in patients with long-standing small bowel CD ( Fig. 3.11 D-new) Ampullary lesions may explain some “idiopathic pancreatitis” in CD .

An image with four gastrointestinal views showing normal papilla, papilla with dysplasia, mucinous neoplasm, and ampullary adenoma. The image set shows four labeled endoscopic views (A–D) of the duodenum and ampullary region, demonstrating normal anatomy and pathological changes. Image A depicts a normal duodenal papilla indicated by a green arrow, with a smooth mucosal surface typical of healthy anatomy. Image B shows a normal-appearing papilla under narrow-band imaging, marked with a blue arrow, but clinically significant for underlying low-grade dysplasia in a patient with familial adenomatous polyposis. Image C illustrates mucin discharge from an intraductal papillary mucinous neoplasm in a patient with ulcerative colitis, with the mucin appearing bubbly as it spreads across the mucosal surface. Image D presents an ampullary tubulovillous adenoma in a patient with long-standing small bowel Crohn’s disease, characterized by swollen mucosal folds and a diffusely inflamed appearance. Collectively, these views contrast normal findings with neoplastic and inflammatory conditions, emphasizing the varied presentations of gastrointestinal pathology in different clinical contexts. — Figure 3.11

Jejunum

Normal jejunum contains plicae circulares (muscular flaps or valves of Kerckring) and villi ( Fig. 3.11 A). Diseases limited to jejunum only are rare. CD and its postoperative changes are examples ( Figs. 3.11 B, C, and D). ( Fig. 3.12 ).

An image with four jejunal views showing normal anatomy, Crohn’s-related ulcers, an inflammatory stricture, and a surgical stricturotomy site. The image set contains four labeled endoscopic views (A–D) of the jejunum, contrasting normal anatomy with Crohn’s disease–related changes. Image A shows a normal jejunum with clearly visible plicae circulares, also known as the muscular flaps or valves of Kerckring, along with healthy villi projecting from the mucosal surface. Image B depicts a dilated jejunal lumen in a patient with Crohn’s disease, characterized by small ulcers distributed along the plicae circulares, indicating active inflammation. Image C presents an inflammatory stricture located in the mid-jejunum of another Crohn’s disease patient, showing narrowing and distorted mucosal architecture. Image D demonstrates the outlet of a surgical stricturotomy site in a patient with small bowel Crohn’s disease, reflecting post-surgical changes to alleviate obstructive pathology. The accompanying caption identifies these findings under ‘Fig. 3.12-new. Jejunum in the healthy and diseased,’ with each description corresponding to the labeled images.

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15:20:14 – Normal gastrointestinal tract and variations on endoscopy

Abbreviations

ATZ

CD

GI

IBD

ICV

NSAID

PSC

SCAD

UC

Introduction

Esophagus

Stomach

Duodenum

Jejunum

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Basicmedical Key

Fastest Basicmedical Insight Engine

15:20:14 – Normal gastrointestinal tract and variations on endoscopy

Abbreviations

ATZ

CD

GI

IBD

ICV

NSAID

PSC

SCAD

UC

Introduction

Esophagus

Stomach

Duodenum

Jejunum

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