Sandbox:Reddy 2

Overview

Liver abscess is a pus-filled cavity inside or attached to the liver. Common causes are an abdominal infection such as appendicitis or diverticulitis. With treatment the prognosis of liver abscess is poor with a mortality rate is 10-30%.. Biliary tract disease is the most common cause but no cause identified in the majority of patients. There are nonspecific clinical findings hence a high degree of suspicion required for diagnosis. There are most often single, rather than multiple foci. Hyperbilirubinemia and elevated alkaline phosphatase are seen in the majority of patients, but it has a low specificity. E. coli is the most common causative organism, followed by Klebsiella, Streptococcus, and Bacteroides species. Rare cause is bowel perforation following foreign body ingestion. Therapy for solitary liver abscess from causes other than bowel perforation is intravenous antibiotics and percutaneous US- or CT-guided drainage. Therapy for liver abscess caused by bowel perforation or foreign body is open surgical drainage. Amoebic liver abscess occurs in 94% of cases of amebiasis. Liver abscess can be caused rarely as complication of percutaneous radiofrequency ablation for hepatic tumors.

Causes

Liver abscess can be caused by variety of micro-organisms. The most common cause is E. coli followed by Klebsiella, Streptococcus, and Bacteroides species. The following is a list of organisms which can cause liver abscess:

Liver abscess

Amoebic liver abscess

Pyogenic liver abscess

Fungal abscess

Entamoeba histolytica

Bacteria

Candida species

Gram-positive aerobes

Gram-negative enterics

Anaerobic organisms

Acid fast bacilli

Streptococcus sp Staphylococcus aureus / Staphylococcus epidermidis Actinomyces sp Enterococcus sp Streptococcus milleri

Escherichia coli Salmonella typhi Yersinia enterocolitica K.pneumonia Pseudomonas sp Proteus sp Eikenella corrodens Others

Bacteroids sp Fusobacterium Anaerobic/ Microaerophilic streptococci Other anaerobes

Mycobacterium tuberculosis

Differential Diagnosis

Pyogenic liver abscess must be differentiated from:

Disease	Causes	symptoms											Lab Findings	Imaging Findings	Other Findings
		Fever	Pain		cough	Hepatomegaly	Jaundice	Weight loss	Anorexia	Diarrhoea or Dysentry	Nausea and vomiting	Stool
			Abdominal pain (right upper quadrant pain)	Pleuritic pain
Amoebic liver abscess	Entamoeba histolytica	✔✔✔	✔✔✔	✔/✘	✔	✔✔/✘	✔ (late stages)	✔ (late stages)	✔	✔	✔		Hypoalbuminemia (✔)	Ultrasound is the gold standard technique for diagnosing amoebic liver abscess	Respond well to chemotherapy and rarely require drainage Marked male predominance More common in developing countries Sero-positive Right lobe is more frequently involved
Pyogenic liver abscess	Bacteria Gram-positive aerobes Gram-negative enterics Anaerobic organisms Acid fast bacilli	✔	✔	✔✔	✔✔	✔/✘	✔✔✔	✔ (acute loss)	✔		✔	Pale/dark	Hypoalbuminemia (✔✔✔)	Cluster sign CT scan shows cluster sign Aggregation of multiple low attenuation liver lesions in a localized area to form a solitary larger abscess cavity	Abnormal pulmonary findings Diabetes mellitus increases the risk Medical-surgical approach is indicated More common in developed countries Culture positive and sero-negative Both lobes are commonly involved
Fungal liver abscess	Candida species Aspergillus species	✔	✔	✔/✘	✔	✔	✔	✔	✔	✔	✔			CT and Us findings with four patterns of presentation: Wheel-within-a-wheel pattern Bull’s-eye configuration pattern Uniformly hypoechoic nodule echogenic foci with variable degrees of posterior acoustic shadowing	Less common Pure fungal abscess or associated with pyogenic abscess Candida and Aspergillus are commonly found in the culture of aspirated pus Associated with underlying malignancy or DM
Echinococcal (hydatid) cyst	Echinococcus granulosus		✔		✔		✔ (Obstructive jaundice)	✔	✔				Histology: Hydatid cyst with three layers a.The outer pericyst, which corresponds with compressed and fibrosed liver tissue b.The endocyst, an inner germinal layer c.The ectocyst, a thin, translucent interleaved membrane	Ultrasound: Cystic to solid-appearing pseudotumors Water lily sign Calcifications seen peripherally	Blood or liquid from the ruptured cyst may be coughed up Pruritis
Malignancy (Hepatocellular carcinoma/Metastasis)	Hepatitis B and C Aflatoxins Alcohol Hemochromatosis Alpha 1 antitrypsin deficiency Non alcoholic fatty liver disease	✔	✔ (uncommon)			✔	✔	✔✔			✔✔	Pale/Chalky	High levels of AFP in serum Abnormal liver function tests	Liver biopsy	Other symptoms: Splenomegaly Variceal bleeding Ascites Spider nevi Asterixis