Teaching Case

An 88-year-old male was admitted to the Emergency Department for acute abdominal pain and fever since more than 3 days. Laboratory tests showed elevated acute phase reactants with leukocytosis and elevated liver enzymes. In the suspicion of abdominal sepsis, abdominal US and CT scans were requested.

US demonstrated a single lobular heterogeneous poorly demarcated hypoechoic lesion (Figure 1a) and the suspicion of abscess was raised.

Contrast-enhanced CT scan (Figure 1b) showed in segments VII and VIII a large hypodense, rounded and multiloculated mass with fine septa, consistent with a hepatic abscess. Its content was predominantly hypodense (slightly higher than water) and without enhancement. Peripheral and septa enhancement was observed.

Furthermore, a thin hyperattenuating foreign body, measuring 2.5 cm in length, was detected (Figures 2a and 2b). It was embedded in the duodenal wall and crossed the duodenum until it reached the subhepatic space, where small bubbles of pneumoperitoneum and fat trabeculation were present.

These findings were suggestive of liver abscess as a secondary complication of foreign body duodenal perforation. Surgical intervention revealed perforation of duodenal bulb by a fishbone (Figure 2c), confirming the diagnosis. After specific question, patient confirmed fish consumption 15 days earlier.

Foreign bodies are frequently present in the gastrointestinal tract, most of them are excreted without injury within a week and the incidence of gastrointestinal perforation is low (1%) [1]. Most foreign bodies are fishbones, chicken bones and needles [1, 2].

Diagnosis is complex as patients don’t remember the ingestion and may be asymptomatic or exhibit nonspecific symptoms like abdominal discomfort or nausea. Time interval from foreign body ingestion to the onset of symptoms or complications can be highly variable, being in most cases between 10-15 days [3].

Although ileum is the most frequent site of perforation, perforation of the duodenum has a complication rate three times higher, a more prolonged course than in other locations and usually causes greater lesions because of its anatomical proximity to structures like the liver [2, 3].

Liver pyogenic abscess is a collection of pus caused by an infectious bacterial process. Clinical presentation usually includes fever, abdominal pain and elevation of acute phase reactants and liver enzymes. Most of them are polymicrobial, with Klebsiella pneumoniae and E. Coli being the most common ones [1]. The most frequent causes are abdominal infections (cholangitis, diverticulitis…) by contiguity, via hematogenous or biliary route, or direct inoculation by penetrating trauma (perforations or biopsies).

Liver abscess secondary to gastrointestinal perforation by foreign body is unusual, having a first case published in 1898 [2]. Streptococcus genus is most frequently responsible for this condition [1].

Abdominal CT scan is of utmost importance for the localization of foreign bodies, to detect complications such as obstruction, perforation or abscesses [2], and for surgical planning. Foreign bodies may be missed on axial images so it is useful to evaluate MRP and MIP reconstructions. The key findings are the presence of an intra or extraluminal foreign body, surrounded by inflammatory changes. It is important to emphasize that pneumoperitoneum may be absent if the perforation is contained. When a liver abscess of unknown origin is present, it is very useful to assess possible distant or nearby processes that explain the cause.

Take-home message / Teaching points

Liver abscess is a life-threatening entity that requires a multidisciplinary approach, and it is crucial to determine and resolve the underlying cause.

In the presence of a liver abscess of unknown origin, with no history of abdominal infection, an exhaustive review of the gastrointestinal tract by CT is important, since foreign body perforations usually go unnoticed and are not usually included in the differential diagnosis.