Pyogenic liver abscess is a purulent collection in the liver parenchyma, most often located in the right liver, but it may be found in the left liver, and may be multiple or multilocular. It is a relatively rare disease whose prevalence increases. Its epidemiology has changed today with the preponderance of biliary and colic etiologies.

Figure 1. Inflammatory epigastric swelling.

A 78-year-old lady presented with high grade fever, abdominal pain, nausea with intermittent vomiting, and epigastric swelling. Her medical history included one year ago a choledocho-duodenal anastomosis for multiple choledochal stones, with an uncomplicated postoperative course. On physical examination, the patient had a temperature of 39°c, and tachycardia. There was no clinical icterus. Abdominal examination revealed a very painful inflammatory epigastric swelling, measuring 5 cm in diameter (Fig. 1). There were no signs of peritonitis. Laboratory investigations showed leucocytosis (WBC:19.100/µL), slight cholestasis and elevated ESR and C-reactive protein (CRP: 154 mg/l).

Figure 2. Ultrasound image showing an ill-defined heterogeneous fluid formation sitting in the abdominal wall.

Abdominal ultrasound showed an ill-defined heterogeneous fluid formation sitting in the anterior abdominal wall (Fig. 2).

A contrast-enhanced CT of the abdomen revealed an ill-defined lesion of liquid density, occupying the left lobe, with a thin wall and internal septa enhanced after intravenous contrast administration. This collection was measuring 11.8 cm / 8.2 cm and communicating with the parietal collection (Fig. 3). Serology of amoebiasis was negative.

Figure 3. Axial CT image of the abdomen. Left lobe liver abscess communicating with anterior abdominal wall abscess.

The patient underwent an ultrasound (US)-guided percutaneous drainage via percutaneous catheter drainage (Fig. 4). IV broad spectrum antibiotics, including third-generation cephalosporins and metronidazole were initiated. Since pus culture was negative, broad-spectrum antibiotics were continued.

The outcome was favorable with apyrexia in 48 hours. Abdominal CT scan 72 hours later showed a collapse of the abscess cavity (Fig. 5). The catheter was removed when the patient showed clinical improvement (defervescence and relief from local symptoms) and normalization of laboratory tests. The follow-up ultra-sound examination one month later showed a negligible residual cavity without any liver or abdominal collection.

Figure 4. US-guided percutaneous drainage via percutaneous catheter drainage (arrow).

Pyogenic liver abscesses are uncommon. Although the associated mortality is rare, morbidity and prolonged hospitalization are common. They are characterized by an infectious destruction of the liver parenchyma, that may be of biliary origin (gallstones, cholangitis and malignancies), hematogenous, disseminated by the portal system (diverticulitis, inflammatory bowel disease, intra-abdominal inflammation and malignancies), and in a lesser degree it is related to a direct extension (superinfection of cysts or necrotic tissue, and trauma). Nevertheless, in many cases (up to 25% of patients) no underlying cause is found and the disease is defined as cryptogenic [1].

Figure 5. Axial CT image of the abdomen showing collapse of the abscess cavity.

Indeed, in the case of single abscess, the most common cause is of cryptogenic origin (59%), while in case of multiple abscesses, the most common cause is of biliary origin (45% of cases) [2]. The most common pathogens are Streptococcus species, E. coli, Staphylococcus species and Klebsiella [3]. E. coli is the most common organism found in abscesses of biliary or portal origin while Gram-positive cocci account for most cases of hematogenous or cryptogenic disease [1].

The diagnosis of liver abscess is based on ultrasound and/or CT scan, and confirmed by percutaneous-needle aspiration to identify the bacteria causing the disease [4] [5]. However, before conducting such studies, the physician must suspect liver abscess based on the patient’s symptoms or laboratory data. The classic symptoms like fever, chills, malaise, nausea and jaundice, and most laboratory examination abnormalities are nonspecific and indicate systemic infections. Abdominal pain, with painful hepatomegaly and abnormal liver function tests are more specific but are not always present.

Some patients may have less abdominal pain and more symptoms or examination abnormalities related to infection of the respiratory and urinary tracts, causing missed diagnoses of liver abscess at emergency departments. Such patients may have serious local and systemic complications. In fact, inflammatory phenomena, linked to hepatic sepsis, may cause thrombosis of the portal system or hepatic veins. More rarely, large abscesses may rupture either into the peritoneal cavity, or into adjacent structures (including the pleural and pericardial spaces). To our knowledge, no case of rupture into the parietal wall of the abdomen has been reported before.

In our case, in addition to the specific and non-specific signs, the patient presented an abscess of the abdominal wall that has guided us towards performing ultrasound and CT scan in order to specify the depth extension of this collection.

Imaging allows the positive and lesional diagnosis of abscesses, as well as allows searching their causes and complications. Ultrasound appearance of a liver abscess is highly polymorphic and less specific. The main contribution of ultrasound is to guide the diagnostic puncture or guide the percutaneous drainage. Liver abscesses may appear as hypoechoic cavities with thick or irregular borders, but a hyper echoic appearance is possible due to high protein content. They may be unilocular or with internal septa.

In CT scan, abscess appears as an uni- or multilocular poorly limited hypodense mass. The fibrous tissue around the abscess often measures one centimeter or thicker, and gradually merges into the liver parenchyma. A common finding is the presence of air in the cavity. After intravenous contrast administration there is a faint, thin, rim enhancement and perilesional edema-image called “Target sign”.

Once the diagnosis of liver abscess is confirmed, the treatment should be initiated urgently. Image-guided intervention and anti-microbial therapy are the mainstay of treatment while open surgical intervention is rarely required [6] [7]. Several studies [8] [9] [10] [11] have shown that a large proportion of patients can be treated, with excellent results, by a combination of parenteral antibiotics (usually cephalosporins or quinolones plus metronidazole and/or aminoglycosides) and image-guided percutaneous drainage using continuous catheter drainage, which is more efficient than repeated needle aspiration.

However, surgery remains necessary after the failure of the initial treatment and should also be considered as an early intervention for cases presenting with gas-forming abscesses and septic shock, and when treatment of the underlying cause is immediately required [12].

Abdominal wall abscess is a very rare complication of liver abscess, which is a serious condition requiring prompt diagnosis by imaging investigations. Treatment should be initiated urgently, combining antibiotics adapted to the causative organism - when it is found - and imaging-guided percutaneous drainage. Surgery is exceptionally required and is limited, almost exclusively, to cases with failed percutaneous treatments.

Dr. Taoufik Lamsiah and Dr. A En-nafaa from Military Teaching Hospital Moulay Ismail, Meknes, Morocco recommend the publication of this article.