Subhepatic appendiceal abscess with an appendicolith

Clinical History

A 76-year-old lady known to have sigmoid diverticulitis for the past 4 months and on treatment, presented with severe right illiac fossa pain. Pain had been increasing in severity for 1 week. The referring surgeon suspected a perforated diverticulitis.

Imaging Findings

Axial, sagittal and coronal images (Fig. 1a-d) of the present study show a well-defined, large, encapsulated collection in the subhepatic location. It contains multiple air loculi (Fig. 1a-e and 1g) and a tiny dependent calcification (Fig. 1e-h) suggestive of an appendicolith. A linear hyperdense structure is noted within the collection which may represent pooled contrast media (Fig 1e and 1g). The previous CT (Fig 2a-c) of the same patient done 4 months before for diverticulitis, shows the subhepatic location of the appendix which is a normal anatomical variant.

Discussion

Subhepatic appendix is an uncommon position of the appendix. Inflammation of this appendix is a very rare condition. The various locations of the vermiform appendix are retro-caecal (65%), pelvic (31%), sub-caecal (2.2%), pre-ileal (1%) and post-ileal (0.4%). Subhepatic and lateral pouch are very rare sites [1].
Sub-hepatic position of the appendix results from an arrested descent of the caecal base into the right illiac fossa [1]. Ruptured appendix in a subhepatic position is very rare. It is very common to mistake this for a liver abscess on imaging. This patient had a previous CT available, hence the subhepatic location of the appendix can be verified. The imaging findings favouring an abscess are the enhancing thick walls, presence of gas within the lumen and appendicolith [5]. The differential diagnosis of appendix adenocarcinoma should be considered if a solid mass is seen. There is associated periappendiceal fat stranding, lateral conal fascial thickening and Gerota's fascial thickening [3]. Gas and calcification are rarely components of malignancy [2, 3]. Laparoscopic exploration may be indicated in cases, which do not provide clear imaging findings. The Ochsner Sherren regimen (to treat infection, relieve pain and supplement the fluids and electrolytes over a period of 48-72 hours) has become outdated. The best management approach now is to drain the abscess, followed by an elective appendectomy [4].

Differential Diagnosis List

Final Diagnosis

Subhepatic appendiceal abscess

URL:	https://eurorad.org/case/12086
DOI:	10.1594/EURORAD/CASE.12086
ISSN:	1563-4086