Appendicitis
Epidemiology and Etiology:
- Adolescents and
young adults mainly
- 7% lifetime risk
- Obstruction à ischemia (collapse of draining
veins)à infection
- Obstruction in
50-80% of cases
- Fecalith usually
- Gallstone
- Tumour
- Nematodes (oxyuriasis vermicularis)
- Unknown pathogenesis
of non-obstructive cases
Common sites:
Gross features:
- early:
- dull, granular,
red serosa
- then:
- then:
- late:
- large areas of
hemorrhagic green ulceration
- green-black
gangrenous necrosis
Histologic features:
- neutrophils extending from mucosa to at least muscularis propria
- early stages:
- scant neutrophils in mucosa, submucosa,
and muscularis propria
- congested serosal vessels with perivascualar
neutrophils
- then:
- fibrinopurulent exudates over serosa
- then (acute suppurative appendicitis):
- abscess within wall
- ulcerations and
foci of suppurative necrosis in mucosa
- late (acute
gangrenous appendicitis):
- hemorrhagic
ulceration of the mucosa
- necrosis
extending to the serosa
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- clinical:
- pain, periumbilical to RLQ (note may be in atypical
locations – right flank, LUQ)
- nausea/vomiting
- abdominal
tenderness particularly in region of appendix (may be deceptively
absent)
- mild
fever
- elevated
WBCs to 15-20 thousand cells/microlitre
- false positive
diagnosis of 20-25% is accepted
- complications:
- suppurative
peritonitis
- pyelophlebitis with thrombosis of the portal venous drainage
- liver
abscess
- bacteremia
References: