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Surgical Pathology Criteria
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Ulcerative Colitis

Definition

  • Idiopathic chronic inflammatory bowel disease primarily involving the mucosal layer of the large intestine

Alternate/Historical Names

  • (Idiopathic) Inflammatory bowel disease (encompasses both ulcerative colitis and Crohn disease and implies that other specific causes and diseases have been ruled out)

Diagnostic Criteria

  • The diagnosis of ulcerative colitis requires clinicopathologic correlation
  • Inflammation is largely limited to mucosa and superficial submucosa
    • Ulceration is generally shallow and does not extend into muscularis propria
    • In fulminant colitis there may be destruction of the full mucosal and submucosal layers, and fissures and inflammation may involve the muscularis propria
      • Lacks the fibrosis typical of Crohn disease
      • May lead to toxic megacolon
  • Neutrophilic infiltrate is present if disease is active
    • Involves epithelium of surface and crypts
    • Frequently forms crypt abscesses
  • Chronic inflammatory infiltrate is present in the lamina propria and submucosa
    • Lymphocytes, plasma cells, eosinophils
    • Basal lymphoid aggregates may be present
    • Granulomas are not seen
  • Architectural changes characterized by crypt distortion are present in both active and inactive (quiescent) disease
    • These findings are important as they demonstrate the chronic nature of the process
    • Crypt / glandular abnormalities
      • Irregular, horizontal, dilated crypts
      • Gland dropout is frequent
      • Bifid, forked glands
      • Shortened glands that fail to reach the muscularis mucosae
    • Lamina propria fibrosis may be present
    • Thickening of muscularis mucosae
    • Minimal architectural distortion may be seen in pediatric cases at initial presentation
    • Complete resolution of architectural changes after a long period of disease inactivity is unusual but may be seen
  • Process nearly always involves a contiguous segment of colorectum
    • Rectum is nearly always involved
      • Therapeutic enemas may mask rectal disease
    • Proximal extent is variable
      • Disease limited to the rectum is termed ulcerative proctitis
    • Patchy involvement and skip lesions are rare
      • The appendix and appendiceal orifice may be involved in the absence of other right side disease and does not constitute grounds for changing the diagnosis
    • Caution should be used in the diagnosis of cases with rectal sparing or skip lesions
    • Terminal ileum may be involved in cases of pancolitis
      • Termed “backwash ileitis”
    • Nonspecific gastric abnormalities may be seen in patients with UC (Lin)
      • Most common is a focal lamina propria infiltrate of lymphocytes, neutrophils and histiocytes
      • Diffuse chronic duodenitis is seen in a few cases
  • Paneth cell metaplasia may be prominent
    • Paneth cells are rare in the normal left colon
  • In extensively ulcerated cases, islands of residual inflamed mucosa are termed pseudopolyps
  • Clinically and histopathologically intractable disease should prompt close inspection and immunohistologic staining for cytomegalovirus
  • The presence of dysplasia predicts the development of colorectal carcinoma in ulcerative colitis
  • Indeterminate colitis
    • Diagnosis used for cases in which a definitive separation of ulcerative colitis and Crohn disease cannot be made
    • May constitute up to 15% of cases
    • Most are cases of fulminant colitis
    • With long term follow-up, 80% of such cases are found to be ulcerative colitis
    • This diagnosis should be reserved for resection specimens
    • Endoscopic biopsy specimens that are not definitive may be designated as “Inflammatory Bowel Disease, Unclassified"

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 11/11/09, 10/29/10

Dysplasia in Inflammatory Bowel Disease

  • The presence of dysplasia predicts the development of colorectal carcinoma in ulcerative colitis and Crohn disease
    • Dysplasia is best evaluated in areas without significant acute inflammation
      • If acute inflammation is present, dysplasia should be diagnosed only if the dysplastic findings are clearly disproportionate to the degree of inflammation
    • Dysplastic features should be present on the luminal bowel surface
      • Reactive atypia rarely extends to the luminal surface
    • Dysplasia may be focal, requiring adequate sampling
      • Recommended sampling is 4 biopsies every 10 cm of colorectum
    • A diagnosis of dysplasia should be confirmed by an experienced gastrointestinal pathologist
  • Low grade dysplasia demonstrates cytologic features identical to those of colorectal adenomas
    • Densely packed, enlarged, elongated nuclei
    • Mucin depletion is common
  • High grade dysplasia demonstrates markedly atypical features
    • Marked cytologic atypia
    • Complete loss of polarity
    • Cribriform gland formations
  • Indefinite for dysplasia should be used if the lesion is suggestive of but not diagnostic of dysplasia
    • Frequently used if acute inflammation is present
  • Sporadic adenomas can be confused with dysplasia
    • Polypoid growths that resemble sporadic tubular adenomas both endoscopically and microscopically and can be completely removed endoscopically can be considered sporadic adenomas rather than dysplasia
    • Sessile lesions in areas involved by inflammatory bowel disease should be considered dysplasia
    • Both sessile and polypoid lesions in areas not involved by the inflammatory bowel disease should be considered adenomas

Differential Diagnosis

  • Fungal, mycobacterial, amebic and other parasitic diseases must all be ruled out by close inspection and by laboratory tests
  • In cases of ulcerative colitis refractory to treatment, cytomegalovirus must be ruled out immunohistochemically (link)
  • Quiescent colitis may be histologically indistinguishable from the effects of radiation or chemotherapy or chronic ischemia
    • Clinical correlation is necessary
  • Segmental colitis associated with sigmoid diverticular disease may be histologically identical to ulcerative colitis
    • Clinical correlation is necessary
Ulcerative Colitis Crohn Disease
Inflammation limited to mucosa and superficial submucosa Transmural inflammation
Contiguous disease, no skip lesions Discontinuous, patchy disease with skip lesions
Limited to colon May involve entire GI tract
No granulomas Granulomas may be present
Predominantly neutrophilic infiltrate with crypt abscesses Predominantly lympho-histiocytic infiltrate
Perinuclear anti-neutrophilic cytoplasmic antibody (pANCA) favors ulcerative colitis Anti-Saccharomyces cerevisiae antibody (ASCA) favors Crohn disease
  • The distinction may be impossible on biopsies and always requires clinical correlation
  • Rare cases deviate from some of these criteria
  • Up to 15% of cases may be indeterminate even after full evaluation
  • pANCA and ASCA have considerable overlap and are felt by some to lack clinical utility

Ulcerative Colitis Acute Self-limited Colitis
Basal lymphoid aggregates frequent Basal lymphoid aggregates absent
Neutrophil infiltrate in crypts with frequent crypt abscesses Neutrophil infiltrate predominantly in lamina propria
Inflammation involves all levels of mucosa Inflammation largely restricted to upper and mid zones of mucosa
Architectural changes of chronic colitis are present Architecture is preserved
Duration at least 6 months Short duration
Common organisms include Salmonella, Shigella, Campylobacter, Yersinia and viruses

Eosinophilic (Allergic) Proctocolitis Ulcerative Colitis
May occur <12 months of age Very rare <12 months
Marked tissue eosinophilia >60/10 HPF May have moderate numbers of eosinophils

Incidental Chronic Colitis Ulcerative Colitis
Virtually restricted to cecum/right colon Involves rectum with contiguous disease proximally in most cases
Incidental, asymptomatic Nearly always symptomatic

  • Histologically indistinguishable

Clinical

  • The risk of carcinoma is elevated in both ulcerative colitis and Crohn disease
  • A diagnosis of high grade dysplasia frequently leads to colectomy
  • A diagnosis of low grade dysplasia may result in a variety of clinical responses
    • Some merely increase the frequency of follow up screening
    • Some recommend colectomy, especially if the dysplasia is identified in multiple sites or on subsequent endoscopy
  • A diagnosis of indefinite for dysplasia typically leads to medical therapy and rebiopsy after inflammation is reduced
  • A diagnosis of no dysplasia usually results in routine follow up endoscopy in 3 to 5 years

Bibliography

  • Noffsinger A, Fenoglio-Preiser CM, Maru D, Gilinisky N.  Gastrointestinal Diseases, AFIP Atlas of Nontumor Pathology, First Series, Fascicle 5, 2007
  • Matsumoto T, Nakamura S, Shimizu M, Iida M. Significance of appendiceal involvement in patients with ulcerative colitis. Gastrointest Endosc. 2002 Feb;55(2):180-5.]
  • D'Haens G, Geboes K, Peeters M, Baert F, Ectors N, Rutgeerts P. Patchy cecal inflammation associated with distal ulcerative colitis: a prospective endoscopic study. Am J Gastroenterol. 1997 Aug;92(8):1275-9.
  • Yang SK, Jung HY, Kang GH, Kim YM, Myung SJ, Shim KN, Hong WS, Min YI. Appendiceal orifice inflammation as a skip lesion in ulcerative colitis: an analysis in relation to medical therapy and disease extent. Gastrointest Endosc. 1999 Jun;49(6):743-7.
  • Odze RD. Pathology of indeterminate colitis. J Clin Gastroenterol. 2004 May-Jun;38(5 Suppl):S36-40.
  • Swan NC, Geoghegan JG, O'Donoghue DP, Hyland JM, Sheahan K. Fulminant colitis in inflammatory bowel disease: detailed pathologic and clinical analysis. Dis Colon Rectum. 1998 Dec;41(12):1511-5.
  • Lin J, McKenna BJ, Appelman HD. Morphologic Findings in Upper Gastrointestinal Biopsies of Patients With Ulcerative Colitis: A Controlled Study. Am J Surg Pathol. 2010 Oct 19. [Epub ahead of print]
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