Inflammatory bowel disease

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Inflammatory bowel disease, abbreviated IBD, is the bread 'n butter of gastroenterology.

It exists in two main flavours:

  • Crohn's disease (CD).
  • Ulcerative colitis (UC).

Both are associated with an increased risk of colorectal carcinoma.[1]

Clinical

  • It is important to differentiate UC and CD as the management is different.
  • UC patients get pouches... CD patients do not.

Epidemiology

  • NOD2/CARD15 variants are assoc. with stricturing CD, early need for surgery and recurrence.[2]

Microscopic

Features helpful for the diagnosis of IBD - as based on a study:[3]

  1. Basal inflammation, i.e. crypt base, plasmacytosis with severe chronic inflammation.
    • Basal cell plasmacytosis makes an infectious etiology less likely.[4]
    • "Basal plasmacytosis" = plasma cells in the lamina propria between the crypts and muscularis mucosae.[5]
  2. Crypt architectural abnormalities.
    • Atrophy = less glands ~ 3-4 glands/mm (normal = 7-8 glands/mm).
    • Branching = common (normal = very rare branching).
    • Distortion = bent glands, marked size variation (normal = "rack of test tubes").
  3. Distal Paneth cell metaplasia.
    • Paneth cells should not be in the left colon[6] - if you see 'em think of IBD and other long-standing injurious processes.
    • Some claim that (friendly right colonic) paneth cells and paneth cell metaplasia look quite different and can be distinguished.[7]

Notes:

  1. Microscopic features can be remembered by mnemonic CPP: Crypts (abnormal), Plasmacytosis, Paneth cells where they don't belong.
  2. If you see architectural distortion (e.g. crypt branching) in the left colon, look for Paneth cells.
  3. The hepatic flexure is considered the divider for normal paneth cells and abnormal paneth cells, i.e. paneth cells proximal to the hepatic flexure are normal; paneth cells distal to the hepatic flexure are abnormal.[8]
  4. Stretching of tissue may mimic atrophy; tip-off it is artefact: thinning of mucosa.[9]

Grading

  • Several systems exists.[10]
  • One that is often cited is by Gupta et al..[11]

Grading schemes for IBD in a table

Nil Mild Moderate Severe
"A grading scheme"[12] - cryptitis PMN abscesses erosions
Gupta[11] "0" (nil) "1" (<50% of crypts
have PMNs) 		"2" (>50% of crypts
have PMNs) 		"3" (presence of
ulcers or erosions)

Crohn's disease vs. ulcerative colitis

Robbins

UC features:[13]

  • Mucosal involvement -- sometimes submucosa.
  • No skip lesions.
  • Colon/rectum only.
    • UC may have 'ileal backwash' -- mild ileal inflammation due to backwash of inflammatory soup from colon.
  • "No granulomas".
    • Superficial granulomas in the mucosa are non-specific, especially if they are beside an inflammed crypt, i.e. they may be present in UC.[14][15]
      • Deep granulomas are specific for Crohn's disease.

Example of a superficial granuloma that is non-specific, i.e. this could be UC or CD:

Kirsch

Features of UC[16] - memory device DDDR:

  • Diffuse inflammation.
  • Diffuse arch. changes.
  • Diffuse atrophy.
  • Rectal involvement.

Words of caution

The following may be present in UC:[17]

  • Cecal patch (cecal involvement without pancolitis).
  • Patchy involvement
    • Esp. in Tx'ed patients.
    • Esp. in children.
  • Ileitis - esp. in the context of severe pancolitis; known as backwash ileitis.
  • Deep inflammation (in a fissure).
  • Upper GI tract involvement -- see below.

Upper gastrointestinal tract involvement

  • The old dogma was upper GI tract = Crohn's disease.

Characteristics of upper GI tract UC:[18]

  • Most common:
    1. Focal gastritis.
    2. Mixed basal inflammation and superficial plasmacytosis in the stomach.
  • Unique:
    • Diffuse chronic duodenitis.
    • ~ 10% of UC patients.
    • ~ 40% of UC + colectomy + pouchitis.

A tabular comparison

Gross pathology:

Feature Crohn's disease Ulcerative colitis
Lesion distribution patchy diffuse
Strictures maybe no
Perianal disease yes/no no
Rectal involvement no yes
Ileal involvement yes, classic usu. no; seen in pancolitis
Upper GI tract involvement yes yes (gaining acceptance)
Associated with PSC ? yes

Ulcerative colitis

General

  • Often abbreviated as UC.

Epidemiology

Gross

  • Conventionally considered to be contiguous, i.e. no "skip lesions", with rectal involvement being most severe.
  • Dependent on the study one reads... rectal sparing may be seen in 15% of UC patients.[21]

Microscopic

  • Lack of granulomas.
  • No full wall-thickness inflammation.

Crohn's disease

General

  • Often abbreviated as CD.

Gross

Microscopic

Features:[3]

  • Segmental crypt architectural abnormalities.
  • Mucin depletion -- less goblet cells. (???)[22]
  • Mucin preservation at the active sites.
  • Focal chronic inflammation without crypt atrophy.

"Indeterminate colitis"

  • "Indeterminate colitis" is a confusing term and should be avoided.[23]

Terminology

  1. IBDU = IBD unclassified.
  2. CUTE = Colitis of uncertain type or etiology.
    • Should be reserved for resection specimens only.

See also

References

  1. ↑ Schmidt C, Bielecki C, Felber J, Stallmach A (June 2010). "Surveillance strategies in inflammatory bowel disease". Minerva Gastroenterol Dietol 56 (2): 189–201. PMID 20485256.
  2. ↑ Alvarez-Lobos M, Arostegui JI, Sans M, et al. (November 2005). "Crohn's disease patients carrying Nod2/CARD15 gene variants have an increased and early need for first surgery due to stricturing disease and higher rate of surgical recurrence". Ann. Surg. 242 (5): 693–700. PMC 1409853. PMID 16244543. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1409853/.
  3. ↑ 3.0 3.1 Tanaka M, Riddell RH, Saito H, Soma Y, Hidaka H, Kudo H (January 1999). "Morphologic criteria applicable to biopsy specimens for effective distinction of inflammatory bowel disease from other forms of colitis and of Crohn's disease from ulcerative colitis". Scand. J. Gastroenterol. 34 (1): 55–67. PMID 10048734.
  4. ↑ RK. 13 December 2010.
  5. ↑ "Pathology of ulcerative colitis". http://www.histopathology-india.net/UlCol.htm. Retrieved 17 January 2011.
  6. ↑ Tanaka M, Saito H, Kusumi T, et al (December 2001). "Spatial distribution and histogenesis of colorectal Paneth cell metaplasia in idiopathic inflammatory bowel disease". J. Gastroenterol. Hepatol. 16 (12): 1353–9. PMID 11851832. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0815-9319&date=2001&volume=16&issue=12&spage=1353.
  7. ↑ Rubio CA, Nesi G (2003). "A simple method to demonstrate normal and metaplastic Paneth cells in tissue sections". In Vivo 17 (1): 67–71. PMID 12655793.
  8. ↑ STC. 14 December 2009.
  9. ↑ RK. 13 December 2010.
  10. ↑ RK. 13 December 2010.
  11. ↑ 11.0 11.1 Gupta RB, Harpaz N, Itzkowitz S, et al. (October 2007). "Histologic inflammation is a risk factor for progression to colorectal neoplasia in ulcerative colitis: a cohort study". Gastroenterology 133 (4): 1099–105; quiz 1340–1. doi:10.1053/j.gastro.2007.08.001. PMC 2175077. PMID 17919486. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2175077/.
  12. ↑ RK. 13 December 2010.
  13. ↑ Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease (7th ed.). St. Louis, Mo: Elsevier Saunders. pp. 850. ISBN 0-7216-0187-1.
  14. ↑ Shepherd, NA. (Aug 2002). "Granulomas in the diagnosis of intestinal Crohn's disease: a myth exploded?". Histopathology 41 (2): 166-8. PMID 12147095.
  15. ↑ Mahadeva, U.; Martin, JP.; Patel, NK.; Price, AB. (Jul 2002). "Granulomatous ulcerative colitis: a re-appraisal of the mucosal granuloma in the distinction of Crohn's disease from ulcerative colitis.". Histopathology 41 (1): 50-5. PMID 12121237.
  16. ↑ RK. 13 December 2010.
  17. ↑ RK. 13 December 2010.
  18. ↑ Lin J, McKenna BJ, Appelman HD (November 2010). "Morphologic findings in upper gastrointestinal biopsies of patients with ulcerative colitis: a controlled study". Am. J. Surg. Pathol. 34 (11): 1672–7. doi:10.1097/PAS.0b013e3181f3de93. PMID 20962621.
  19. ↑ Beaugerie, L.; Sokol, H. (Aug 2009). "Appendicitis, not appendectomy, is protective against ulcerative colitis, both in the general population and first-degree relatives of patients with IBD.". Inflamm Bowel Dis. doi:10.1002/ibd.21064. PMID 19685454.
  20. ↑ 20.0 20.1 Timmer, A.; Obermeier, F. (2009). "Reduced risk of ulcerative colitis after appendicectomy.". BMJ 338: b225. PMID 19273505.
  21. ↑ Bernstein CN, Shanahan F, Anton PA, Weinstein WM (September 1995). "Patchiness of mucosal inflammation in treated ulcerative colitis: a prospective study". Gastrointest. Endosc. 42 (3): 232-7. PMID 7498688.
  22. ↑ McCormick DA, Horton LW, Mee AS (February 1990). "Mucin depletion in inflammatory bowel disease". J. Clin. Pathol. 43 (2): 143–6. PMC 502296. PMID 2318990. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC502296/.
  23. ↑ Geboes K, Colombel JF, Greenstein A, et al. (June 2008). "Indeterminate colitis: a review of the concept--what's in a name?". Inflamm. Bowel Dis. 14 (6): 850–7. doi:10.1002/ibd.20361. PMID 18213696.
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