Appendiceal adenocarcinoma complicated by retroperitoneal abscess

Case contributed by Dr Francis Fortin

Presentation

Acute abdominal pain

Patient Data

Age: 85 years
Gender: Male
CT

Initial abdominopelvic CT

Retroperitoneal abscess seen to arise from the tip of the appendix. This was initially read as complicated appendicitis. However, notice how there is an expansive tissue-density rounded lesion in the appendiceal tip. This should raise suspicion of an underlying tumour. Also, note how little fat stranding there is surrounding the tip of the appendix. This is also quite unusual if considering typical acute appendicitis.

Annotated image

Annotated images

On the annotated coronal image, one can clearly see the appendix (blue) arising from the base of the caecum (green), with the rounded lesion (red) representing the suspected tumour. The retroperitoneal abscess is highlighted in yellow.

On the annotated axial images, one can also appreciate the zone of ulceration (purple) in the suspected appendiceal tip tumour (red) communicating with the retroperitoneal abscess (yellow).

Nuclear medicine

Post-operative PET-CT scan a few months later

Post-operative PET-CT scan shows high uptake posterior to the caecum, suspicious for residual tumour and/or peritoneal carcinomatosis.

Case Discussion

This case highlights the importance of carefully assessing the luminal contents and surrounding areas when considering acute appendicitis. Though the findings here are retrospectively quite evident, the endoluminal mass in the tip of the appendix was initially missed and the patient was taken to surgery for appendicectomy and drainage of the retroperitoneal abscess.

Pathology revealed a low-grade adenocarcinoma of the appendix with at least T3 staging, but suspicious for T4a. Subsequent imaging, confirmed by exploratory laparotomy, showed peritoneal carcinomatosis. Over the course of more than one year, the peritoneal implants showed slow growth in the patient's desire to forgo chemotherapy.

In cases of radiologically suspected tumour mimicking an uncomplicated acute appendicitis, the surgeon should be notified preoperatively as the surgical approach will likely be altered.

 

Case courtesy of Dr Odile Prosmanne, abdominal radiologist at the Centre Hospitalier de l'Université de Montréal.

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Case information

rID: 58007
Published: 26th Jan 2018
Last edited: 16th Jul 2018
Inclusion in quiz mode: Included

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