Gastroenterology Research, ISSN 1918-2805 print, 1918-2813 online, Open Access
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Review

Volume 9, Number 2-3, June 2016, pages 29-38

Common Inflammatory Disorders and Neoplasia of the Ileal Pouch: A Review of Histopathology

Figures

Figure 1.
Figure 1. Histology of normal pouch (a) and pouchitis (b, c). (a) This pouch biopsy shows normal histology (H&E stain, × 20). The small bowel mucosa demonstrates preserved and slender villous projection into the lumen. There are a few mononuclear inflammatory cells in the lamina propria but without expansion of the lamina propria. There is no basal lymphoplasmacytosis, neutrophilic inflammation, epithelial injury, erosion or ulceration. (b, c) This pouch specimen shows small bowel mucosa with villous blunting, erosion, chronic and active inflammation (b, H&E, × 100; c, H&E stain, × 200), features of chronic pouchitis.
Figure 2.
Figure 2. Crohn’s disease of the pouch. This biopsy shows small bowel mucosa with mononuclear inflammatory expansion of the lamina propria (not included in the photo) and one well-formed non-caseating epithelioid granuloma in one lymphoid aggregate (H&E stain, × 200). In the right clinical setting, this finding supports the diagnosis of Crohn’s disease of the pouch.
Figure 3.
Figure 3. Pouch biopsy with epithelium negative for dysplasia. This biopsy shows small bowel mucosa with chronic active inflammation, architectural distortion, erosion, pyloric gland metaplasia, and regenerative epithelial changes (H&E stain, × 100). A few glands show slightly enlarged, hyperchromatic, pencil-shaped nuclei. However, the aforementioned findings are seen in proximity to an erosion and there is at least partial maturation, thus, these changes should be interpreted as negative for dysplasia.
Figure 4.
Figure 4. Pouch biopsy with low-grade dysplasia. This pouch biopsy shows low-grade dysplasia which is characterized by epithelium containing enlarged, hyperchromatic, pencil-shaped nuclei without surface maturation (H&E stain, × 100). This lesion does not show obvious nuclear pleomorphism or architectural complexity, features of high-grade dysplasia.
Figure 5.
Figure 5. Pouch biopsy with high-grade dysplasia. This pouch biopsy shows glands with enlarged, hyperchromatic nuclei without surface maturation (a, H&E stain, × 100). The glands show marked pleomorphism, high nuclear to cytoplasmic ratio, and abnormal mitotic figure (b, H&E stain, × 400).
Figure 6.
Figure 6. Pouch adenocarcinoma. This adenocarcinoma is well differentiated, contains abundant extracellular mucin, and invades the muscularis propria (a, H&E stain, × 20; b, H&E stain, × 40).

Table

Table 1. Summary of Clinicopathological Features of Common Inflammatory Disorders of the Ileal Pouch
 
EntityDuration of symptomsClinical response to antibiotic treatmentPre-pouch ileumPouchRectal cuffOther features
N/A: not applicable. PGM: pyloric gland metaplasia. *C. difficile pouchitis may respond to anti-C. difficile antibiotic treatment.
Pouch inflammation of no clinical significanceN/AShould not be treated with antibiotics+/-Variable degree of acute and chronic inflammation+/-Asymptomatic
Acute pouchitisAcute onset, < 4 weeks symptom durationAntibiotic- responseVariably involvedAcute inflammation, crypt abscess, chronic inflammation (+/-)+/-
Chronic pouchitis> 4 weeks symptom duration and/or > 3 attacks in a 12-month periodAntibiotic- response, antibiotic- dependent, or antibiotic-refractory+/-Acute inflammation, crypt abscess, chronic inflammation, PGM (+/-)+/-
Secondary infectious pouchitisVariableAntibiotic- refractory*+/-Acute inflammation, crypt abscess, chronic inflammation (+/-), PGM (+/-), granulomatous inflammation (in some fungal infection)+/-Viral inclusion, fungal organisms on special stain, or positive stool C. difficile toxin results
Ischemic pouchitisVariableAntibiotic- refractoryRelatively normalAcute inflammation, crypt abscess, chronic inflammation (+/-) , PGM (+/-), variable fibrosisRelatively normalAsymmetric and well demarcated inflammation of the pouch by endoscopy, hematoidin or hemosiderin deposits
Autoimmune pouchitisVariableAntibiotic- refractory+/-Acute inflammation, crypt abscess, chronic inflammation, villous blunting, PGM (commonly present)+/-Prominent deep crypt apoptosis
Crohn’s disease of the pouchVariableAntibiotic- refractoryVariably involvedAcute and chronic inflammation, crypt abscess, villous blunting, PGM (common), non-caseating granuloma (10-12% cases)Variably involvedStricture or ulceration away from staple lines, and/or fistula occurring ≥ 3 months after ileostomy reversal, involvement of upper gastrointestinal tract
Idiopathic pre-pouch ileitisVariableAntibiotic- refractoryAcute and chronic inflammation, villous blunting, PGM (common)NormalNormal
CuffitisVariableAntibiotic- refractoryRelatively normalRelatively normalChronic active colitis pattern