Liver abscesses are localised collections of necrotic inflammatory tissue caused by bacteria (polymicrobial ,pyogenic), parasite or protozoa( E histolytica, amoebic-producing anchovy paste appearance of the contents) , helminiths and fungal agents. Infection elsewhere such as abdominal sepsis are common source. Liver abscess is common in immunocompromised and diabetics. About 15% of patients with, HIV / AIDS ,elderly, post chemotherapy / transplant recipients and malignancy might have liver abscess. Hepatic trauma with necrosis may also leads to liver abscess. A large group of liver abscess may be due to unknown cause (cryptogenic ).
The typical presentation is one of right upper quadrant pain, fever and jaundice (in some cases). Anorexia, malaise and weight loss are also frequently seen. Depending on the immune status of the patient, and the organism involved, presentation may be sudden orgradual.
As a general rule, bacterial and fungal abscesses are often multiple, whereas amoebic abscesses are more frequently single. Amoebic abscesses are more common in a sub-diaphragmatic location and are more likely to spread through the diaphragm and into the chest. A plain abdominal radiograph may reveal evaluating right lobe of diaphragm. Other findings may be gas within the abscess or biliary tree (pneumobilia) and right sided pleural effusion
Ultrasound : Liver abscesses are typically poorly demarcated with a variable appearance, ranging from predominantly hypoechoic (with some internal echoes ) to hyperechoic. Gas bubbles may also be seen. Liver abscesses on CT is variable, in general they appear as peripherally enhancing well outlined wall and centrally low density lesions . Occasionally they appear solid, or contain gas.
Treatment and prognosis
Medical antimicrobial (Pyogenic) and anti protozoal (amoebic) therapy is required in all cases, and sometimes suffices if abscesses are small.
Percutaneous drainage of hepatic abscesses can be performed either under ultrasound or CT guidance when the abscess is small ,unilocular with thick wall .
Surgery is the definitive strategy which offers adequate drainage,debribement and biopsy of the abscess wall. Additionally, the source of the abscess may be detected and its surgical treatment (if needed) may be done at the same time.
Prognosis is highly variable, depending of not only the organism involved and size of the abscess, but also the co-morbidities present.