Appendicitis

Author: Mikael Häggström
Appendicitis may histopathologically be defined as neutrophilic infiltrates of the wall of the appendix in the correct clinical context.

  See also: General notes on fixation

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

• Minimal depth
• (Moderate depth)
• ((Comprehensive))

Gross proccessing

Acute suppurative appendicitis: The organ is enlarged and sausage-like (botuliform). This longitudinal section shows red inflamed mucosa with an irregular luminal surface. It was removed early in the disease, with no late complications like transmural necrosis, perforation, and abscess formation.

Standard sections if the appendix appears inflamed and there are no signs of malignancy. Further information: Appendix

Microscopic evaluation

Suppurative acute appendicitis, with ulceration seen at left in lumen.

• Evaluate depth of the inflammation.
• Look for any perforation of the wall.
• (Attempt to specify the type of appendicitis as either of the following:)

Types

Acute suppurative appendicitis with transmural inflammation, with associated perforation (at right).

Classification of acute appendicitis based on gross pathology and light microscopy characteristics

Pattern	Gross pathology	Light microscopy	Clinical significance
Acute intraluminal inflammation	None visible	Only neutrophils in lumen No ulceration or transmural inflammation	Probably none
Acute mucosal inflammation	None visible	Neutrophils within mucosa, and possibly in submucosa Mucosal ulceration	May be secondary to enteritis.
Suppurative acute appendicitis	May be inapparent. Dull mucosa Congested surface vessels Fibropurulent serosal exudate in late cases Dilated appendix	Neutrophils in mucosa, submucosa and muscularis propria, potentially transmural. Extensive inflammation Commonly intramural abscesses Possibly vascular thrombosis	Can be presumed to be primary cause of symptoms
Gangrenous/necrotizing appendicitis	Friable wall Purple, green or black color	Transmural inflammation Necrotic areas Extensive mucosal ulceration	Will perforate if untreated
Periappendicitis	May be inapparent. Serosa may be congested, dull and exudative	Serosal and subserosal inflammation, no further than outer muscularis propria	If isolated, probably secondary to other disease
Eosinophilic appendicitis	None visible	>10 eosinophils/mm2 in muscularis propria. No changes conforming to other types of appendicitis	Possibly parasitic, or eosinophilic enteritis.
Chronic appendicitis	Fibrosis	Predominantly mononuclear infiltrate rather than neutrophilic.	Should preferably correlate with long-term or recurrent symptoms.

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