Teaching Case

A 78-year-old man presented with right lower quadrant abdominal pain and bile emesis. An abdominal X-ray demonstrated an ovular opacity with calcified walls.

A 78-year-old man presented with deteriorating health, abdominal pain and bile emesis. Objective examination demonstrated muscular resistance in the right lower quadrant and sharp pain on palpation. An abdominal X-ray was performed. It demonstrated an oval opacity with calcification of the walls. Differential diagnosis included iliac vessel aneurysm, large bowel diverticulum or mucocoele. For this reason an abdominal-pelvic CT was performed using spiral multidetector equipment

Mucocoele is a rare lesion that is found in only 0.2-0.3% cases of appendectomy. The pathology is associated with dilation of the vermiform appendix by intraluminal accumulation of mucoid material; possible causes are non-neoplastic obstruction of the lumen or neoplastic obstruction due to mucosal secretion by mucinous appendicular cystoadenoma or cystoadenocarcinoma.

The diagnosis of mucocoele is frequently an incidental finding during examination for other pathology because of the aspecificity of its symptoms. Possible complications are rupture (causing pseudomyxoma peritonei), malignant trasformation, or obstruction caused by intussusception, so a precise diagnosis is required.

Abdominal X-ray and ultrasound studies do not seem to have sufficient diagnostic accuracy. Multidetector spiral CT without administration of intravenous contrast medium reveals the presence of an ovular lesion in the lower right part of the abdomen with densitometry characteristic of dense-fluid tissue and calcified walls. Continuity with the lumen of the caecum and a clear cleavage plane with the iliac vessels are well demonstrated by coronal 2D reconstruction. These findings exclude the presence of a diverticulum or iliac vessel aneurysm and confirm the diagnosis of a mucocoele.