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Miscellaneous Benign Lesions and Conditions of the Stomach, Duodenum, and Small Intestine
Benign disorders of the foregut originate in the genes and the environment of the stomach, duodenum, and small intestine. Embryologic events orchestrate anatomic and cellular variations that predispose the adult foregut to obstructive and neoplastic conditions. Webs, stenosis, duplications, and a variety of ectopic and heterotopic cellular occurrences are uncommon and may remain asymptomatic until adulthood. Genetic mutations and environmental stressors have a relationship with hyperplasia and benign tumors. Environmental factors such as drugs, alcohol, and smoking cause foregut inflammation and mucosal injury. For the most part, these benign foregut conditions do not need operative management, and most commonly are found incidentally on endoscopic or radiologic examination. On occasion, benign conditions are discovered at the time of surgery for other disorders of the foregut, and require an operative decision about how and why to perform an excisional biopsy. Diagnostic upper gastrointestinal endoscopy, capsule endoscopy, and widespread utilization of abdominal computed tomography (CT) uncover many of these benign conditions. Management of foregut disorders has improved with endoscopic ultrasound (EUS), which provides a diagnosis by ultrasound image-defined criteria, ultrasound-directed aspiration biopsy, and when indicated by endoscopic mucosal or submucosal resection.
Inflammatory gastropathies will be covered in other chapters, as will gastrointestinal polyposis syndromes, gastrointestinal stromal tumors (GISTs), and carcinoid tumors. Foregut intussusception, congenital webs, and duplications are discussed in another chapter but figure prominently in any discussion of miscellaneous conditions of the stomach, duodenum, and small intestine in adults. Rare in children, these congenital variations in foregut anatomy are rarer in adults and typically present with vague symptoms and difficulty in diagnosis with modern as well as traditional imaging techniques.
Benign Lesions of the Stomach, Duodenum, and Small Intestine
Benign Lesions of the Stomach
Benign lesions of the stomach include heterotopic pancreas, pancreatic acinar metaplasia, gastric adenomyoma, chronic gastritis, acute gastritis, collagenous gastritis, eosinophilic gastritis, granulomatous gastritis, malakoplakia, cytomegalovirus infection, fungal infection, graft-versus-host disease, peptic ulcer, duplication, diverticula, cysts, hyperplastic polyp, adenoma, lipoma, fundic gland polyp, polyposis syndrome, inflammatory fibroid polyp, Ménétrier disease, gastric antral vascular ectasia (GAVE), telangiectasia, neurogenic tumors, glomus tumor, and many others. In a study of a 12-year experience with 10,000 gastric specimens accumulated over 12 years, 8579 benign gastric conditions were described ( Table 66.1 ). The most common inflammatory conditions of the stomach are chronic gastritis and peptic ulcer disease with Helicobacter pylori seen in the majority of specimens. Foveolar hyperplastic polyps are notable for harboring malignant foci and dysplastic glands in 2% to 3% of cases, demonstrating the potential they have in the transition from dysplasia to carcinoma. Fundic gland polyps are benign lesions that have neither clinical relevance nor risk of malignant transformation. Heterotopic pancreas has a characteristic endoscopic appearance that may be mistaken for adenocarcinoma unless deep biopsies are taken. Pancreatic acinar metaplasia is an incidental microscopic lesion that is problematic when misdiagnosed as cancer. Gastric amyloidosis is a manifestation of systemic disease often related to multiple myeloma and chronic inflammatory disease.
TABLE 66.1
Prevalence of Various Lesions Among 8570 Benign Gastric Lesions
| Benign Lesions | No. of Cases (%) |
|---|---|
| Almost normal stomach | 74 (0.9) |
| Chronic gastritis | 4374 (51.0) |
| Benign peptic gastric ulcer | 2195 (25.6) |
| Foveolar hyperplastic polyp | 1004 (11.7) |
| Fundic gland polyp | 421 (4.9) |
| Adenoma | 487 (5.6) |
| Heterotopic pancreas | 9 (0.1) |
| Pancreatic acinar metaplasia | 8 (0.1) |
| Amyloidosis | 7 (0.1) |
Benign Lesions of the Duodenum
Benign lesions of the duodenum include heterotopic pancreas, heterotopic gastric mucosa, duplication, atresia, diverticulum, celiac disease, tropical sprue, Whipple disease, amyloidosis, parasite infestation, duodenal ulcer, duodenitis, acquired immune deficiency syndrome (AIDS)-related inflammatory disease, fungal infection, cytomegalovirus infection, radiation duodenitis, Brunner gland hyperplasia, Brunner gland adenoma, adenoma, hamartomatous polyp, endometriosis, inflammatory fibroid polyp, lipoma, hemangioma, lymphangioma, telangiectasia, neurofibroma, ganglioneurofibroma, and congenital fibromatosis. In a review of pathologic reports of 615 duodenal specimens collected over 10 years, 567 benign lesions and 48 malignant lesions were identified. The benign lesions were identified as chronic nonspecific duodenitis in 334 cases (60.0%), duodenal ulcer in 101 cases (17.8%), heterotopic gastric mucosa in 81 cases (14.3%), hyperplastic polyp in 16 cases (2.8%), Brunner gland hyperplasia in 14 cases (2.5%), Brunner gland adenoma in 8 cases (1.4%), lymphoid polyp in 5 cases (0.8%), tubular adenoma in 4 cases (0.7%), lymphangioma in 2 cases (0.4%), endocrine cell micronests in 1 case (0.2%), and amyloidosis in 1 case (0.2%).
Similar to the stomach, duodenitis and ulcer disease are the most common benign duodenal conditions. Heterotopic gastric mucosa is a rare disorder that may be congenital or acquired and consists of two types: foveolar epithelium and fundic glands. Surgical awareness is important because adenoma and adenocarcinoma on rare occasion arise in heterotopic gastric mucosa. Hyperplastic polyps are usually in the first and second portions of the duodenum, and they too may very rarely undergo malignant transformation. Brunner gland hyperplasia is usually seen in the first and second portion of the duodenum. Adenoma and carcinoma arising in Brunner gland hyperplasia occurs but is almost as rare as hen's teeth. Lymphoid polyps are uncommon and are important only in their differentiation from lymphoma.
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