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The gastrointestinal tract begins with the mouth, leads to the esophagus and extends through the stomach, small and large intestine, to end at the anus.  During the journey, food is broken down and nutrients absorbed. Finally, within the large intestine, water is resorbed and the remaining fecal matter is expelled. Pathologists are often called into the operating room to open a segment of intestines (bowel) to determine if a process is cancerous or inflammatory.

Carcinoid and Neuroendocrine Tumors of the Gastrointestinal Tract
Cyclic Vomiting Syndrome
Crohn's Disease
Eosinophilic Gastroenteritis
Extra-Gastrointestinal Stromal Tumors
Gastrointestinal Stromal Tumors
Hereditary Non-polyposis Colorectal Cancer (HNPCC)
Hernia Sac
Idiopathic Retroperitoneal Fibrosis
Juvenile Polyps
Microvillous Inclusion Disease (Familial Microvillous Atrophy)
Familial Polyposis Syndromes (Gardner's, Peutz-Jegher's Syndrome, etc.)
Pseudomyxoma Peritonei
Sclerosing Mesenteritis
Ulcerative Colitis


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Upper Gastrointestinal Tract Injury in Patients Receiving Kayexalate (Sodium Polystyrene Sulfonate) in Sorbitol Clinical, Endoscopic, and Histopathologic Findings

Susan C. Abraham, etal.

Am J Surg Pathol 2001;25:637-644 Abstract quote

Kayexalate (sodium polystyrene sulfonate) in sorbitol has been demonstrated to cause colonic necrosis in a subset of uremic patients who are administered the cation exchange resin for treatment of hyperkalemia. Upper gastrointestinal damage associated with Kayexalate in sorbitol is reported far less frequently, and the clinicopathologic spectrum of disease in cases with upper gastrointestinal damage has not been investigated previously.

The authors studied the clinical, endoscopic, and histologic features of 11 patients with Kayexalate crystals in biopsies from the esophagus (n = 7), stomach (n = 6), and duodenum (n = 2). The endoscopic appearance was markedly abnormal in all 11 patients. The effects of the medication closely mimicked other endoscopic and radiologic diagnoses in three cases, including esophageal carcinoma, Candidal esophagitis, and gastric bezoar.

Histologic and/or endoscopic evidence of mucosal injury in the form of an ulcer or erosion was present in nine patients (82%). In four patients with mucosal injury, no other etiology apart from Kayexalate in sorbitol could be identified. In comparison with a cohort of patients with Kayexalate crystals in lower gastrointestinal specimens identified during the same period (11 patients) the frequency of associated mucosal damage was not significantly different (55%, p = 0.19), but no patient with upper gastrointestinal Kayexalate required surgical resection or died as a result of Kayexalate-induced mucosal injury.

The results of this study provide evidence that Kayexalate in sorbitol can induce damage to the upper gastrointestinal tract. Recognition of Kayexalate crystals in histologic sections as a marker for sorbitol-induced mucosal damage may aid in establishing the correct diagnosis for clinically or endoscopically misleading lesions.



Relative frequency of upper gastrointestinal and colonic lesions in patients with positive fecal occult-blood tests.

Rockey DC, Koch J, Cello JP, Sanders LL, McQuaid K.

Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.

N Engl J Med 1998 Jul 16;339(3):153-9 Abstract quote

BACKGROUND: Although bleeding lesions anywhere in the gastrointestinal tract can cause a positive reaction on guaiac-based fecal occult-blood tests, the relative frequency of upper gastrointestinal and colonic lesions is unknown.

METHODS: During a period of 30 months, we prospectively studied all patients with at least one stool specimen containing fecal occult blood who were referred for further evaluation. Fecal occult blood was detected by standard guaiac-based tests of stool specimens obtained as part of routine screening or of stool obtained by digital rectal examination. Patients with documented iron-deficiency anemia or active gastrointestinal bleeding were excluded from the study. All participants had a detailed history taken and underwent colonoscopy, followed by esophagogastroduodenoscopy.

RESULTS: Of the 409 patients with fecal occult blood who were referred, 310 were potentially eligible to participate, and 248 (mean age, 61 years; range, 40 to 89) were studied; 40 percent were women. We identified lesions consistent with occult bleeding in 119 patients (48 percent); in 71 bleeding lesions were found in the upper gastrointestinal tract, and in 54 they were identified in the colon. Six patients had abnormalities in both areas. The most common upper gastrointestinal lesions were esophagitis (23 patients), gastric ulcer (14), gastritis (12), and duodenal ulcer (10). Thirty patients with lesions in the upper gastrointestinal tract were long-term users of aspirin, ethanol, nonsteroidal antiinflammatory drugs, or a combination of these substances. The most common colonic lesions were adenomas more than 1.0 cm in diameter (29 patients), carcinoma (13), colitis (5), and vascular ectasia (5). Although the overall sensitivity of symptoms for the detection of gastrointestinal lesions was low, logistic-regression analysis demonstrated that the presence of symptoms in the upper gastrointestinal tract was associated with the detection of lesions in the upper gastrointestinal tract (odds ratio, 2.6; 95 percent confidence interval, 1.4 to 4.7). In both patients with symptoms and those without symptoms, the prevalence of lesions in the upper gastrointestinal tract was greater than or equal to that of colonic lesions.

CONCLUSIONS: In a group of patients with positive fecal occult-blood tests who were referred for further evaluation, from which those with iron-deficiency anemia and active bleeding had been excluded, upper gastrointestinal lesions were identified more frequently than colonic lesions.


Elastosis and Elastofibromatous Change in the Gastrointestinal Tract
A Clinicopathologic Study of 13 Cases and a Review of the Literature

Christine M. Hobbs, MD, CDR David M. Burch, MC, USN, and Leslie H. Sobin, MD
Am J Clin Pathol 2004;122:232-237 Abstract quote

We describe 13 cases in which the submucosa and muscularis mucosae of the gastrointestinal tract exhibited a focal or diffuse increase of elastin fibers. This elastosis or elastofibromatous change most commonly manifested as a colonic polyp and usually was found during screening colonoscopy. Gastric and small intestinal cases were less frequent and associated with ulcers or an inflammatory process. The literature includes reports of 13 gastrointestinal elastotic lesions with a topographic distribution similar to that in our series.

Histologically, elastosis appears as finely granular and/or fibrillar amphophilic material, sometimes with a fibrous component (elastofibromatous change). The changes occasionally appear centered around blood vessels and often are mistaken for amyloid but are negative for Congo red stain and strongly positive for elastin stain.

We believe that this lesion might be more underrecognized than rare. In 2 of 26 cases, elastotic lesions also were present in nongastrointestinal sites.

Histopathologic studies of colorectal postendoscopic resection sites: "skipping electrothermal injury" associated with endoscopic resection procedures.

Matsukuma S, Goda K, Sakai Y, Ikegawa K, Morita D, Kuwabara N.

Department of Pathology, Japan Self Defense Forces Central Hospital, Tokyo.

Am J Surg Pathol 1999 Apr;23(4):459-64 Abstract quote

To elucidate the pathologic changes due to endoscopic resection (ER), 32 post-ER sites in 24 surgically removed colorectal specimens and the previous ER specimens were examined. The depth of all the previous ER specimens was restricted to the submucosa, and all post-ER sites showed submucosal stromal changes of various degrees.

Fourteen sites (43.8%) showed muscular or serosal changes. One of these lesions was considered to be a reaction to a tattoo agent, but all the other lesions were considered to represent skipping electrothermal injury caused by electrical current passing through the colorectal wall. The lesions consisted of muscular depletion in the inner layer of the muscularis propria (12 sites, 37.5%), hemorrhage or fibrosis between the inner and outer layers of the muscularis propria (3 sites, 9.4%), and serosal changes (10 sites, 31.3%). These skip regions would be vulnerable to electrical current.

These findings suggest that asymptomatic electrothermal injury associated with ER is frequent. Statistically, the electrothermal injury appeared to be related to the size of the previous ER specimens. However. these results also reveal that the ER of tissues <10 mm can cause electrothermal injury and can result in full-thickness necrosis.


Computed tomographic image of an inflammatory fibroid polyp of the stomach.

Fuke H, Hashimoto A, Shimizu A, Yoshimura H, Nakano T, Shiraki K.

Internal Medicine, Saiseikai Matsusaka General Hospital, Matsusaka, Japan.
Clin Imaging. 2003 Nov-Dec;27(6):400-2 Abstract quote.  

Inflammatory fibroid polyp (IFP) is a rare benign lesion of the gastrointestinal tract.

We report a case of IFP and its computed tomographic (CT) findings. On CT, the tumor protruded into the stomach and was covered with mucosa that was well enhanced. The inside of the tumor was irregularly enhanced, reflecting the typical histological findings of IFPs.

Not only endoscopy and endoscopic ultrasonography (EUS) but also CT findings may be useful to diagnose IFP before polypectomy.

Chronic Antral Ulcer Associated With Gastroduodenal Lymphocytic Phlebitis.

Abraham SC, Solem CA, Hauser SC, Smyrk TC.

From the Departments of *Pathology and Laboratory Medicine and daggerGastroenterology and Hepatology, Mayo Clinic, Rochester, MN.
Am J Surg Pathol. 2004 Dec;28(12):1659-1663. Abstract quote  

Enterocolic lymphocytic phlebitis (ELP) is a rare cause of gastrointestinal ischemia. Unlike most vasculitic diseases affecting the gastrointestinal tract, ELP involves only the mural and mesenteric veins, which are surrounded by a lymphocytic and sometimes granulomatous infiltrate. The mesenteric arterial system and the systemic vasculature are characteristically spared.

Most patients with ELP present with an acute abdomen that resolves following surgical resection of the involved bowel. ELP has been reported to involve the small bowel, colon, or both, but involvement of the upper gastrointestinal tract has not been previously described.

Here we report a case of lymphocytic phlebitis that affected only the stomach and duodenum. The patient, a 68-year-old man, had a nonhealing gastric antral ulcer and underwent hemigastrectomy with vagotomy and Billroth II reconstruction. Both the resected stomach and duodenum showed characteristic lymphocytic and granulomatous infiltrates that involved the submucosal and mural veins, with associated obliteration of vascular lumina; the adjacent arteries were completely spared. The patient developed late postoperative complications including bile reflux gastritis and erosive esophagitis, but he had no recurrence of gastrointestinal ulceration or ischemia over a 2-year follow-up.

We hypothesize that there may be more cases of upper gastrointestinal ELP than are diagnosed as such, in part because the diagnosis can be made only on surgical resections specimens.

Adenocarcinomas of the gastrointestinal tract with prominent rhabdoid features.

Amrikachi M, Ro JY, Ordonez NG, Ayala AG.

Department of Pathology, Baylor College of Medicine, Houston; the Department of Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, TX.


Ann Diagn Pathol 2002 Dec;6(6):357-63 Abstract quote

Rhabdoid tumor, first described in kidneys of infants and children, is an aggressive tumor that has been reported in several extrarenal locations. Gastrointestinal tumors with rhabdoid features are extremely rare. The effect of the rhabdoid phenotype on the aggressiveness of gastrointestinal tumors remains unclear.

We present four cases of rhabdoid tumors of the gastrointestinal tract involving the esophagus, stomach, and small intestine and discuss the clinicopathologic, immunohistochemical, and ultrastructural features. In the four cases reported herein, the patients' ages ranged from 52 to 73 years, and tumor size ranged from 3.8 to 13 cm in greatest dimension. The noncohesive rhabdoid cells exhibited an eccentric nucleus with a paranuclear inclusion, which was shown by electron microscopic examination to be composed of intermediate filaments. On immunohistochemical staining, the tumor cells were positive for vimentin and cytokeratin. Three patients developed distant metastasis shortly after diagnosis and died of disease within 2 to 10 months after initial presentation.

A retrospective review of outcomes of the current cases and previously published literature showed that 12 (75%) of the 16 patients died within 6 months of presentation. Recognition of the rhabdoid phenotype in gastrointestinal tract neoplasms is important because this feature is associated with poor prognosis and unresponsiveness to conventional therapy.


Endoscopic tattoo agents in the colon. Tissue responses and clinical implications.

Lane KL, Vallera R, Washington K, Gottfried MR.

Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA.

Am J Surg Pathol 1996 Oct;20(10):1266-70 Abstract quote

Laparoscopic surgery frequently requires tattooing of endoscopically identified sites for localization during surgery. Some tattooing agents cause serious tissue injury, which must be recognized in pathologic examination.

Seven surgically resected colons were reviewed after injection with methylene blue or India ink at intervals of 1 day to 7 weeks before surgery. Early reactions to India ink included necrosis, edema, and neutrophilic infiltration in the submucosa and muscularis propria. Vessels were inflamed but without fibrinoid necrosis. Early reactions to methylene blue included ischemic ulceration, necrosis, and eosinophilic infiltration in the submucosa as well as fibrinoid necrosis of vessel walls. In the repair of methylene-blue injury, obliterative intimal fibrosis was seen in vessels. Such changes were absent in the colons injected with India ink.

The India ink remained remained visible with the naked eye and microscopically 7 weeks after injection. Methylene blue was not grossly visible 7 days after injection, and only microscopic particles of pigment remained in widely scattered macrophages. In light of these findings, the amount of ink injected should be minimized and the injection site should be completely resected at surgery. Methylene blue is a poor tattoo agent, but its occasional use continues, and pathologists should recognize the resulting reaction.


CD97, but Not Its Closely Related EGF-TM7 Family Member EMR2, Is Expressed on Gastric, Pancreatic, and Esophageal Carcinomas

Gabriela Aust, PhD
Matthias Steinert, MD
Alexander Schütz, MD
Carsten Boltze, MD
Mandy Wahlbuhl
Jörg Hamann, PhD
Manja Wobus, PhD


Am J Clin Pathol 2002;118:699-707 Abstract quote

CD97 expression is related closely to the dedifferentiation and tumor stage in thyroid carcinomas. We systematically examined the role of CD97 and its closest relative, EMR2, in normal and malignant gastric, esophageal, and pancreatic tissue.

The normal tissues were EMR2–, whereas CD97 was expressed slightly in the parietal cells of gastric mucosa and in exocrine pancreatic cells. Interestingly, intralobular and interlobular pancreatic ducts were CD97+.

All tumors were EMR2–. CD97 was expressed by 44 of 50 gastric, 14 of 18 pancreatic, and 10 of 13 esophageal carcinomas. Of the 44 gastric cancers, 27 showed disseminated or scattered tumor cells at the invasion front with stronger CD97 expression than tumor cells located in solid tumor formations. There was no correlation between CD97 levels in the tumors or soluble CD97 in the serum samples and the clinicopathologic features of the patients. Taken together, significant numbers of gastric, esophageal, and pancreatic carcinomas are CD97+, whereas its homolog, EMR2, does not have any role in such tumors.

Expression of mucins and cytokeratins in primary carcinomas of the digestive system.

Lee MJ, Lee HS, Kim WH, Choi Y, Yang M.

Departments of Pathology (MJL, HSL, WHK) and Preventive Medicine (MY) and Cancer Research Institute (WHK, YC, MY), Seoul National University College of Medicine, Seoul, Korea.

Mod Pathol 2003 May;16(5):403-10 Abstract quote

To determine the most optimal treatment of cancer patients, it is fundamental to classify human carcinomas according to their primary anatomical site of origin. As for some patients, it is difficult to identify cancers occurring at obscure location and overlapping adjacent sites.

The aim of this study is to partition the primary site of 486 patients in cancers of the digestive system by the expression pattern of the mucins and cytokeratins typifying each site. The expressions of MUC1, MUC2, MUC5AC, MUC6, CK7, CK8, CK13, CK14, CK18, CK19 and CK20 were evaluated immunohistochemically in 426 adenocarcinomas and 60 hepatocellular carcinomas using the tissue-array method. The finding of MUC series showed their characteristics in case of MUC2 in the appendix cancer and MUC1 and 5AC in pancreas cancer. As for CKs 7, 13, and 19, and 20 had a feature in cancers of common bile duct, liver, and appendix, respectively. We classified cancers in 11 sites by characteristic expression of antibodies. The sensitivity, specificity, positive predictive value, and diagnostic efficacy of significant antibodies were calculated with deducing the dichotomous tree made by SPSS 10.0. Six of 11 antibodies, CK 7, CK13, CK19, CK20, MUC1, and MUC5AC distinguished 6 groups from 11 sites.

We also executed the clustering of cancers to investigate total relationship among cancers. They fell into three categories, which corresponded to embryologic origin. Unlike other sites, the small intestine and colorectum cancers expressed significantly different patterns to their sublocations. Mucins and CKs showed expression patterns to classify the primary sites of digestive cancers and may be helpful in predicting the primary sites of digestive cancers.

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Commonly Used Terms

Mucosa-This is the epithelial surface lining.

Muscularis mucosa-This is a thin layer of smooth muscle lying just below the mucosa.

Muscularis propria-These are thick layers of smooth muscle located between the mucosa and serosal surface. It is divided into an internal and external layer.

Serosa-This is the outermost connective tissue layer.

Submucosa-Below the surface mucosa and lying atop the muscular layers of the gut is the submucosa. 

Basic Principles of Disease
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Last Updated December 10, 2004

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