Sabiston Ch50 - Infectious Enteritis & Small Bowel Neoplasms

Citation: Sabiston Textbook of Surgery, Chapter 50 “Small Intestine” (authors: Tong Gan, B. Mark Evers). Source file: raw/Sabiston Ch50 - Small Intestine.pdf, pages 31–45 of 61 (chunk 2 of the chapter).

Type: Textbook reference chapter — narrative background/orientation, not critically-appraised primary literature. Content is filed as reference and flagged as such throughout.

Scope of this chunk

• Remainder of the Crohn Disease section (colorectal disease surgical principle, perianal disease, duodenal disease, GI bleeding, urologic complications, prognosis and the postoperative surveillance algorithm) — merged into the existing Crohn Disease page
• Typhoid enteritis — new Typhoid Enteritis condition page
• Enteritis in the immunocompromised host (protozoa, bacteria, mycobacteria, viruses, fungi) — new Enteritis in the Immunocompromised Host condition page
• Small bowel neoplasms: general considerations, clinical manifestations, diagnosis, benign neoplasms (stromal tumors, adenomas incl. FAP/Spigelman surveillance and Brunner gland adenomas, lipomas, Peutz-Jeghers hamartomas, hemangiomas), and malignant neoplasms (neuroendocrine tumors/carcinoid syndrome, adenocarcinoma, lymphoma, gastrointestinal stromal tumors) — new Small Bowel Neoplasms overview page plus dedicated Small Bowel Neuroendocrine Tumors (NETs), Small Bowel Adenocarcinoma, and Gastrointestinal Stromal Tumors (GIST) pages

Key points

• Crohn prognosis: ~71% of patients require surgery within 10 years of diagnosis; 50% require a second procedure within 20 years. Endoscopic recurrence reaches 90% within 5 years despite surgery — smoking cessation is the only clearly modifiable recurrence risk factor.
• Typhoid enteritis: caused by Salmonella typhi; perforation (via ulcerated Peyer patches) occurs in ~2% of cases and hemorrhage in up to 20% historically (now lower with antibiotics).
• Immunocompromised enteritis: protozoa (Cryptosporidium, Isospora, Microsporidium) are the most frequent cause of AIDS-associated diarrhea; CMV is the most common viral cause and accounts for a high rate of perforation via mucosal ischemic ulceration.
• Small bowel neoplasm epidemiology: despite the small bowel comprising 75% of GI tract length and 90% of surface area, it accounts for <2% of GI malignancies. Adenocarcinoma is the most common malignant subtype (30–50%), followed by NETs (25–30%) — though NET incidence has risen more than fourfold over three decades and NETs now carry the best prognosis of the small bowel malignancies.
• Carcinoid syndrome requires hepatic metastasis (or extraabdominal disease bypassing first-pass hepatic metabolism) to manifest, since the liver otherwise metabolizes the responsible vasoactive peptides.
• GIST: KIT/CD117 immunohistochemistry positive in >95%; imatinib mesylate (Gleevec) transformed treatment of both localized (adjuvant, 3 years for high-risk) and advanced/metastatic disease. Tumor capsule rupture during resection results in relapse in 100% of cases if it occurs.

Limitations

• Narrative textbook chapter; evidence grading is inconsistent, and several NET-treatment claims cite single named trials (PROMID, CLARINET, RADIANT-4, NETTER-1, TELESTAR) without independent appraisal here.
• The BALLAD trial for small bowel adenocarcinoma adjuvant chemotherapy is described as still accruing subjects at the time of writing — its results are not yet available to synthesize.

Relevance

Substantially expands Crohn Disease; backs the new Typhoid Enteritis, Enteritis in the Immunocompromised Host, Small Bowel Neoplasms, Small Bowel Neuroendocrine Tumors (NETs), Small Bowel Adenocarcinoma, and Gastrointestinal Stromal Tumors (GIST) pages. More chunks of this chapter to follow (diverticular disease, miscellaneous problems).