Pathology Associates Of Lexington, P.A.

Differences between Ulcerative Colitis and Crohn's Disease

(When not cleanly IBD-UC or IBD-CD, then it is "indeterminate" or "atypical" or "mixed" IBD)

One tends to avoid "pouch" surgery if any worry of an IBD-CD component

Features:	Ulcerative Colitis (IBD-UC)	Crohn's Disease (IBD-CD)
Clinical
Rectal Bleeding	Common	Inconspicuous
Abdominal Mass	Practically never	10%-15%
Abdominal Pain	Usually left-sided	Usually right-sided
Sigmoidoscopy	Abnormal in 95%	Abnormal in less than 50%
Free perforation	12%	4%
Colon Carcinoma	5%-10%	Very Rare
Anal Complications	Rare; minor	75% fissures, fistulas, ulceration
Response to steroid therapy	75%	25%
Results of surgery	Very Good	Fair
Ileostomy dysfunction	Rare	Common
Radiographic
	IBD-UC	IBD-CD
Sparing of rectum	Exceptional	90%
Involvement of ileum	Rare; dilated ("backwash ileitis")	Common; constricted
Strictures	Absent	Often present
Skip areas	Absent	Common
Internal fistulas	Absent (unless coexisting abscessing diverticulitis [L06-10218])	May be present
Longitudinal and transverse ulcers	Exceptional	Common
Fissuring...linear ulcers	Absent	Common
Thumb-printing	Absent	Common

Morphologic
	IBD-UC	IBD-CD
Histology, established active	crypt distortion; lam. propria plasma cell filling; polys in lam. propria & crypts; rare mucin granuloma	crypt distortion; lam. propria plasma cell filling; polys in lam. propria; focal (aphthous) ulceration on uninvolved mucosa; sometimes epithelioid granuloma
Histology, quiescent	may not fill with plasma cells; essentially no polys	may not fill with plasma cells; essentially no polys
Distribution of involvement	diffuse; predominantly left-sided & absence of gross or micro "skip" areas; rectal biopsy essentially always abnl	focal; predominantly right-sided & presence of gross &/or micro "skip" areas; rectal biopsy always normal in pure IBD-CD; IBD-CD does not invariably affect terminal ileum [L10-4483]
Depth of inflammation	mucosal and submucosal	transmural
Mucosal atrophy and regeneration	Marked	Minimal
Lumenal epithelial cytoplasmic mucin	Diminished	Preserved
Lymphoid aggregates	Rare	Common; *must see transmural aggregates away* from any ulceration in order to invoke any component of IBD-CD²**
Edema	Minimal	Marked
Hyperemia	May be extreme	Minimal
Granulomas	Absent (isolated giant cells are insignificant)	Present in 60%; especially useful when not just in mucosa and are deeper (from lamina muscularis, thru transmural, to extra-intestinal)²
Fissuring...linear ulcers	Absent (may see in severe relapse [LMC-03-5215])	Present...an important IBD-CD marker when faced with "atypical IBD"[L10-4483].
Ulceration		longitudinal & favor mesenteric aspect
pseudopolyps	present (can become a type of adenomatous polyp [LMC-01-6097])	absent
Crypt abscesses	Common	Rare
Rectal involvement	Practically always	50% of cases
Ileal involvement	Minimal; dilated for not more than 10 cm	50% of cases & constricted; transmural inflammation
Serosal change	unremarkable	creeping of fat seen ONLY when really chronic ileal involvement
Lymph nodes	Reactive hyperplasia	May contain granulomas

References:

Ackerman's Surgical Pathology, 2 vols, 2732 pages, Juan Rosai, M. D., 1996.
Taylor, Shari (fellow & former co-worker with Rodger Haggitt), now at GI Pathology Partners, Memphis...personal communication 12 Aug. 2003 concerning case LMC-03-5215.

(posted 2002; additions 2 November 2010)