Pyogenic Abscess

Occurs via portal vein, arterial system, or bile ducts

Etiology/Pathogenesis

• Bacterial pathogens most common in Western countries

Klebsiella pneumoniae is now most common pathogen, followed by Escherichia coli

Anaerobes are isolated in up to 25% of cases

Significant number are cryptogenic

Clinical Issues

• Diabetes is major risk factor

Other associated conditions include intraabdominal infections, biliary disease, malignancy, cirrhosis

• Presentation includes fever, chills, RUQ pain

Elevated WBC count, ESR, CRP, bilirubin, alkaline phosphatase, transaminases

• Percutaneous drainage and antibiotics are mainstay of therapy

• Major complication is spread of infection

• Mortality ∼ 15% overall

Imaging

• Ultrasound &/or CT mainstay of diagnosis

Macroscopic

• Most abscesses are solitary; multiple abscesses occur in 25-45% of cases

Right lobe most frequent site

Microscopic

• Abundant neutrophils, fibrin, and bile with associated fibrosis

Diagnostic Checklist

• Culture of abscess contents is critical to diagnosis and management

Gross Appearance
This partial hepatectomy specimen shows 2 large, irregular, yellow-tan abscesses with central green bile-stained necrosis.

Abscess With Bile
This section of a large liver abscess shows irregular zones of inflammation and necrosis with associated bile. Another smaller abscess containing bile is present at the top of the section .

Necrosis and Acute Inflammation
In this region of the abscess, necrotic liver parenchyma is identifiable by the ghosts of residual hepatic plate architecture . The necrotic parenchyma is infiltrated with neutrophils.

Fibrosis
Fibrosis may be very prominent, particularly at the edge of an abscess , as seen in this actinomycotic abscess. Marked acute and chronic inflammation are also present.

TERMINOLOGY

Definitions

• Infection featuring localized accumulation of pus with surrounding inflammation and fibrosis

Occurs via portal vein, arterial system, or bile ducts

ETIOLOGY/PATHOGENESIS

Predisposing Conditions

• Diabetes is major risk factor

Other predisposing conditions include malignancy, alcohol abuse, cirrhosis, hypertension, recent surgery, immunosuppression

Abscesses secondary to Yersinia enterocolitica or Yersinia pseudotuberculosis are often associated with underlying hemochromatosis

• Biliary disease

Including biliary ischemia secondary to surgery or ablative procedures

• Trauma

• Intraabdominal infections

• Secondary to sepsis

• Significant number are cryptogenic

Epidemiology

• Bacterial abscesses are most common in Western countries

Klebsiella pneumoniae is now most common pathogen, followed by Escherichia coli

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Tags: Diagnostic Pathology Hepatobiliary and Pancreas

Apr 20, 2017 | Posted by admin in PATHOLOGY & LABORATORY MEDICINE | Comments Off

Basicmedical Key