Ischemic colitis

Ischemic colitis
Diagnosis in short
Ischemic colitis. H&E stain.
LM	withering crypts (colonic epithelium has decreased cytoplasm - NC ratio increased, usually with decreased goblet cells), crypt loss/drop-out, lamina propria hyalinization, submucosa hyalinization, +/-pseudomembranes, +/-vascular thrombi, +/-cryptitis
LM DDx	inflammatory bowel disease, radiation colitis, toxins/drugs, infectious colitis
Gross	dusky appearing, +/-bowel wall thinning, +/-dilation
Site	colon
Associated Dx	atherosclerosis
Clinical history	+/-cardiovascular disease
Signs	+/-blood per rectum, +/-diarrhea (may be non-bloody)
Symptoms	abdominal pain, tenesmus
Blood work	+/-anemia
Prognosis	poor if severe
Clin. DDx	other causes of colitis, esp. infectious colitis

Ischemic colitis is inflammation of the colon due to a compromised blood supply.

It is also known as colonic ischemia and ischemia of the colon.

General

• May occur together with ischemic enteritis, in which case it is known as ischemic enterocolitis.

Etiology

Anything that leads to vascular occlusion:

• Atherosclerosis.
• Vasculitis.
• Embolization, e.g. thrombotic, foreign body.

Possible associated pathology:

• Necrotizing enteritis - necrosis of the small bowel only.
• Necrotizing enterocolitis - necrosis of the small and large bowel.

Closely related:

• Radiation colitis.
• Infectious colitis.

Note:

• Ischemia = compromised blood supply.

Clinical

Classic presentation:

• Abdominal pain.
• Urgency to defecate (tenesmus).
• Bloody diarrhea.

Note:

• Diarrhea may be non-bloody.
  • This is a poor prognosticator and possibly increases the likelihood of not identifying it in time.

Gross

Features - location:

• Luminal part (mucosa & submucosa) affected - edema.
• Splenic flexture of colon commonly affected (vascular watershed).

Note:

• May have pseudomembranes (classically assoc. with C. difficile colitis), i.e. mimics an infectious process.
• DDx for pseudomembranes:
  • C. difficile induced pseudomembranous colitis.
  • Ischemic colitis.
  • Volvulus.
  • Necrotizing infections.
  • ... anything that causes severe mucosal injury.
• Radiologic correlate = bowel wall thickening.

Microscopic

Features:

• Withering crypts - important.
  • Colonic epithelium has decreased cytoplasm - NC ratio increased.
  • Usually with decreased goblet cells.
• Crypt loss/drop-out.
  • Less intestinal crypts present.
• Lamina propria hyalinization.
  • Dense pink material replaces loose connective tissue.
• Submucosa hyalinization.
• +/-Cryptitis.
• +/-Pseudomembranes (microscopic):
  • Loss of surface epithelium.
  • PMNs in lamina propria.
  • +/-Capillary fibrin thrombi.
• +/-Reactive epithelial changes - may mimic dysplasia.

Notes:

• Pseudomembranes arise from the crypts - considered acute.

DDx:

• Inflammatory bowel disease.
• Radiation colitis.
• Toxins/drugs.
  • Rosuvastatin.
  • Cocaine.
  • NSAID overdose.
• Infectious colitis.

Ischemia versus infection on biopsy

Dignan and Greenson created a tabular comparison between ischemia and (C. difficile) infection.

A modified version of the Dignan-Greenson table (below) shows that the two etiologies generally cannot be separated; however, hyalinization appears to be useful if it is present:

Histologic feature	Ischemia (24 cases)	Infection (25 cases)
Atrophic crypts	75%	24%
Lamina propria - haemorrhage	75%	36%
Lamina propria - hyalizization	67%	0%
Diffuse (histologic) pseudomembranes	25%	4%
Mucosal necrosis (full thickness)	58%	28%

Images

• 

  Ischemic colitis - low mag. (WC/Nephron)

• 

  Ischemic colitis - high mag. (WC/Nephron)

• 

  Ischemic colitis - very high mag. (WC/Nephron)

• 

  Colonic pseudomembranes - low mag. (WC/Nephron)

• 

  Colonic pseudomembranes - intermed. mag. (WC/Nephron)

www:

• Ischemic colitis (flickr.com/euthman).

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Biopsy

Left Colon, Biopsy:
- Compatible with ischemic colitis (attenuated epithelium, hyalinized 
  lamina propria, cryptitis).

Comment:
The differential diagnosis includes: drug reaction, infectious etiologies and, less likely, inflammatory bowel disease. Clinical correlation is required.

Block letters

TRANSVERSE COLON, BIOPSY:
- SEVERE ACTIVE COLITIS WITH ATTENUATED EPITHELIAL CYTOPLASM AND ULCERATION.
- CELLULAR DEBRIS.
- NEGATIVE FOR DYSPLASIA AND NEGATIVE FOR MALIGNANCY.

COMMENT:
The attenuated cytoplasm is compatible with ischemia; however, it is not 
accompanied with other suggestive findings (crypt drop out, lamina propria 
fibrosis, pseudomembranes).  The crypt architecture is test tube-like.

The differential diagnosis includes: ischemia, drug reaction, infectious 
etiologies and, less likely, inflammatory bowel disease. Clinical 
correlation is required.

COLON, SPLENIC FLEXURE, BIOPSY:
- PATCHY MODERATE ACTIVE COLITIS WITH ATTENUATED EPITHELIAL CYTOPLASM,
  FOCALLY DECREASED GOBLET CELLS AND ULCERATION.
- NEGATIVE FOR DYSPLASIA AND NEGATIVE FOR MALIGNANCY.

COMMENT:
The findings are consistent with ischemia; however, they are not diagnostic.

The differential diagnosis includes: ischemia, drug reaction, infectious
etiologies and, less likely, inflammatory bowel disease. Clinical
correlation is required.

Biopsy with nonspecific findings/compatible

Colon, Random Biopsies:      
     - Mild acute colitis with mild eosinophilia, see comment.
     - NEGATIVE for significant architectural distortion.

Comment:
The colitis could be due to ischemia, drug reaction, infection or inflammatory 
bowel disease. Clinical correlation is required. 

Short version

LEFT COLON AND SIGMOID COLON, RESECTION:
- PSEUDOMEMBRANOUS COLITIS, SEE COMMENT.
- ONE LYMPH NODE NEGATIVE FOR MALIGNANCY ( 0 POSITIVE / 1 ).
- NEGATIVE FOR DYSPLASIA AND NEGATIVE FOR MALIGNANCY.

COMMENT:
Pseudomembrane formation is a non-specific finding.  It is consistent with ischemia;
however, it may be seen in other contexts, including infection. Clinical correlation is
required.

Long version

RECTOSIGMOID, RESECTION:
- BOWEL WALL ISCHEMIA WITH PERFORATION, SEROSITIS, MICROABSCESS FORMATION AND FOCAL 
POORLY FORMED PSEUDOMEMBRANES.
- NEGATIVE FOR MALIGNANCY.
- PLEASE SEE COMMENT.

COMMENT:
There is no evidence of inflammatory bowel disease:
The unaffected mucosa does not have obvious architectural distortion. No granulomas are
identified. The inflammation is largely associated with necrosis/ischemic changes
and favoured to be reactive.

The poorly formed pseudomembranes are associated with mural ischemic changes; they do not
specifically suggest an infection in this context.

The blood vessels do not show a vasculitis, or significant atherosclerosis.  Thrombi are
seen on several sections and found predominantly in the (smaller) veins. 

Considerations are thrombosis, thromboembolism, mechanical vascular compromise, and
infectious etiologies.  A vascular compromise is favoured as the underlying cause. 

Clinical and radiologic correlation is suggested.

Another long version

SIGMOID COLON, RESECTION:
- BOWEL WALL ISCHEMIA WITH PERFORATION, SEROSITIS, AND FOCAL POORLY FORMED
PSEUDOMEMBRANES.
- MILD ATHEROSCLEROSIS.
- DIVERTICULAR DISEASE.
- TWO LYMPH NODES NEGATIVE FOR MALIGNANCY ( 0 POSITIVE / 2 ).
- PLEASE SEE COMMENT.

COMMENT:
The sections show the changes of acute and chronic ischemic colitis (submucosal fibrosis,
lamina propria hyalinization, focal crypt drop-out, decreased goblet cells, pigmented
macrophages in the lamina propria, intraepithelial neutrophils).

No granulomas are identified. The inflammation is largely associated with
the necrosis/ischemic changes and favoured to be reactive.

The poorly formed pseudomembranes are associated with mural ischemic changes; they do not
specifically suggest an infectious etiology in this context.

The blood vessels do not show a vasculitis. However, focal neutrophilic perivascular 
inflammation is seen; this is probably a reactive process. No vascular thrombi are 
identified.

The findings are compatible with perforation secondary to a foreign body in the setting of
chronic ischemia.

Micro

Negative for ischemic colitis

The sections show colorectal mucosa with preservation of the crypt density and epithelium with a normal nuclear-to-cytoplasm ratio. There is no apparent lamina propria hyalinization. The muscularis mucosa is prominent. Focally, lymphoid aggregates are present.

No cryptitis is present. Neutrophils are not apparent in the lamina propria. No erosions are identified.

The epithelium matures appropriately from the crypt base to the surface.

See also

• Infarction.
• Colon.
• Ischemic enteritis.
• Colonic cast.