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
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
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.
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]
