Diagnostic Ultrasound - Abdomen and Pelvis

Hepatic Diffuse Microabscesses
TERMINOLOGY
Definitions
• Hepatic parenchymal abscesses measuring ~ 1 cm in
diameter
• Typically refers to hepatic candida abscesses in
immunocompromised patients
IMAGING
General Features
• Best diagnostic clue
○ Multiple small liver lesions in patient with neutropenic
fever (fungal abscesses)
○ Less commonly seen in setting of GI or biliary tract
infection and positive blood culture (pyogenic
microabscesses)
• Location
○ Diffusely distributed in liver ±spleen
• Size
○ ~ 1 cm
• Morphology
○ Usually rounded
Ultrasonographic Findings
• Grayscale ultrasound
○ Multiple small hypoechoic lesions throughout liver (most
common pattern)
○ Target sign or bull's-eye configuration
– Central hyperechoic inflammation surrounded by
hypoechoic halo
○ Wheel within wheel pattern may be present in larger
fungal lesions
– Hyperechoic nodule of inflammatory cells with
surrounding hypoechoic halo of fibrosis
– Central hypoechoic area of necrosis within
hyperechoic lesion
○ Multiple small, hyperchoic foci throughout liver (occurs in
later stages)
– Lesions may disappear or calcify after successful
treatment
○ Similar lesions may be found in spleen
CT Findings
• CECT
○ Multiple small, hypodense lesions in liver ±spleen
○ Ill-defined margins
○ No contrast enhancement
DIFFERENTIAL DIAGNOSIS
Simple Cysts
• Typical uniformly hypoechoic/anechoic content
Necrotic Metastases
• May also demonstrate target sign (hypoechoic halo)
• Multiple
• Known primary tumor
Hepatic Lymphoma
• Often see coexisting lymphadenopathy
• Hepatosplenomegaly
Sarcoidosis
• Affects 5-15% of patients with sarcoidosis
• Coexists with pulmonary sarcoid ±splenic sarcoid nodules
• Asymptomatic
Biliary Hamartomas
• Small developmental malformations of intrahepatic bile
ducts
• Hypoechoic or hyperechoic, < 1 cm, may have "comet tail"
artifact
• Asymptomatic
PATHOLOGY
General Features
• Etiology
○ Fungal infection: Most commonly Candida albicans, but
may also include Cryptococcus, histoplasmosis,
mucormycosis, Aspergillus
○ Pyogenic infections can appear similarly in patients with
GI or biliary tract infection
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Fever unresponsive to antibiotic treatment
○ Abdominal pain
○ Deranged liver function
Demographics
• Epidemiology
○ Mostly fungal: Candida albicans
○ Pyogenic: Staphylococcus aureus
○ Rare: Escherichia coli, CMV
Treatment
• Antifungal agents: Amphotericin B, fluconazole
• Liver biopsy with culture often necessary prior to treatment
to verify infectious agent
SELECTED REFERENCES
1. Taşbakan MI et al: Isolated hepatic sarcoidosis mimicking liver
microabscesses: a case report. Ir J Med Sci. 183(3):503-5, 2014
2. Krahn JF et al: Von Meyenburg complexes: a rare cause for multiple hepatic
lesions on transabdominal ultrasound. J Clin Ultrasound. 40(3):174-5, 2012
3. Yellapu RK et al: Education and Imaging. Hepatobiliary and pancreatic:
Candida liver abscesses associated with endocarditis. J Gastroenterol
Hepatol. 25(5):1017, 2010
4. Koyama T et al: Radiologic manifestations of sarcoidosis in various organs.
Radiographics. 24(1):87-104, 2004
5. Mortelé KJ et al: The infected liver: radiologic-pathologic correlation.
Radiographics. 24(4):937-55, 2004
6. Verbanck J et al: Sonographic detection of multiple Staphylococcus aureus
hepatic microabscesses mimicking Candida abscesses. J Clin Ultrasound.
27(8):478-81, 1999
http://radiologyebook.com/
Diagnoses: Liver
227