Teaching Case

A 45-year-old male presented with complaints of upper abdominal pain for one week and fever and vomiting for three days. No past history of significant illness or trauma.

An ill defined non enhancing hypodense collection measuring 6 x 5.5 x 5.5 cm was noted in the left lobe of liver with perilesional oedema. A well defined non enhancing hypodense collection measuring 5.2 x 2.8 x 2.8 cm was noted extending from the medial aspect of duodenum to the fissure for ligamentum teres. A thin linear hyperdense structure measuring 3.5 cm in length was noted within the collection. Mild perihepatic free fluid and fat stranding were present.

Retrospective ultrasound revealed a hypoechoic collection in the subhepatic region with a linear echogenic structure within.

An imaging diagnosis of hepatic abscess and subhepatic collection with foreign body within secondary to upper gastrointestinal perforation was made.

 Laparotomy revealed perforation of the first part of the duodenum, a subhepatic collection with a fish bone within and abscess in the left lobe of liver adjacent to the collection.

Foreign bodies of the gastrointestinal tract are very common, however majority of them are unnoticed.  They drive attention when they cause obstruction or rarely perforation. Presentation of foreign body with liver abscess is rare, the first case being reported in 1898. The common sites for perforation in such cases are stomach and duodenum (2) and the common site of liver abscess being the left lobe due to its anatomical proximity (1). The usual foreign bodies reported causing perforation include fishbone, chicken bone, sewing needle, toothpick etc.

Patients usually present with symptoms like abdominal pain, fever, nausea and vomiting. Most often patients do not remember any episode of foreign body ingestion as in our case. Hence radiology plays an important role in the detection of the foreign body and gastrointestinal perforation. Computed tomography is the most useful imaging modality in identifying the foreign body as well as possible site of perforation (3).

Pyogenic liver abscess usually arises secondary to biliary infections, haematogenous spread through hepatic artery or porta vein or as a result of direct injury. They are more common in the right lobe. The double target sign and cluster sign are characteristically described for pyogenic abscess. The double target sign refers to a central hypodense area surrounded by a hyperdense inner ring and hypodense outer ring. Cluster sign refers to multiple small hypodense lesions coalescing to form a single large abscess. Amoebic liver abscesses are also common on in the right and also in a subcapsular location and are typically solitary (5). Isolated hepatic abscess in the left lobe should alert for the search of rare causes in contrast to hematogenous spread of infection presenting as multifocal lesions and with the right lobe predominance. The perforation may not be evident on imaging always. In our case also the duodenal perforation was not evident on the computed tomography images even on retrospective analysis.

Treatment of the abscess depends on the size. Small abscess less than 5 cm may be treated conservatively with intravenous antibiotics while those larger than 5 cm require drainage (4). Removal of the foreign body usually requires laparoscopy or laparotomy. Non-removal of the foreign body may result in incomplete resolution as well as recurrence of the liver abscess. In the case presented, the patient had to undergo laparotomy with drainage of the abscess and foreign body removal. He recovered well after a course of intravenous antibiotics and was discharged.

To conclude, diagnosis of foreign body induced perforation as the cause of liver abscess needs strong suspicion and an acquaintance of the radiologist to this entity is essential.