The first case of a solitary caecal diverticulum was reported in 1863; more than 500 cases have been recorded since then. The condition is uncommon, seen in only 10 of 5,000 radiological examinations, with greater incidence in Oriental people [
1]. This condition is unrelated to the common and well known multiple colonic diverticular disease which is a common disorder in the West. According to experience in Singapore, the average age of presentation of caecal diverticulitis is 36 years (3–74) with male predominance [
2]. Nearly 80% of caecal diverticula are situated in the area from one cm proximal to two cm distal to the ileocaecal valve [
3]. They are usually solitary. Approximately 60% of solitary caecal diverticula arise from the anterior aspect of the caecum, so when inflamed they tend to perforate and cause peritonitis. However, a posteriorly situated caecal diverticulum may produce a mass without generalized peritonitis, simulating perforating carcinoma. Correct preoperative diagnosis of acute caecal diverticulitis is made only in about 9% of the patients, and most of these patients have had previous appendicectomy. Even peroperatively, the correct diagnosis is only made in about 65% of cases [
4]. Although the aetiology of a solitary caecal diverticulum is uncertain, congenital origin is widely accepted. The theory is that an outgrowth of the caecum develops in the sixth week and atrophies by about the seventh week. If this 'transient appendix' fails to disappear, a diverticulum or a duplication of the appendix results [
5‐
7]. This concept is supported by the fact that the condition has been reported in a 3-year-old girl [
8], the incidence does not increase with age [
9], and it is a true type of diverticulum. Most authors agree that, preoperatively, it is almost impossible to distinguish between acute solitary caecal diverticulitis and acute appendicitis, even retrospectively [
10]. However, some authors believe that the longer duration of illness [
11], the absence of nausea and vomiting [
3], and the relative lack of toxicity [
12], are features of caecal diverticulitis.
There is no standard surgical procedure for the treatment of an inflamed solitary caecal diverticulum. The extent of the inflammation, the experience of the surgeon, and the confidence in the intraoperative diagnosis determine the procedure. Procedures range from simple diverticulectomy to right colectomy, with appendicectomy when only the diverticulum is removed [
1]. Management of an incidentally found solitary caecal diverticulum is more controversial. The condition may be encountered preoperatively, e.g. following a barium enema examination, in which case it is probably sensible to do nothing. Whether to interfere or not, in the case of an asymptomatic solitary caecal diverticulum, should be based on the chances of it becoming inflamed or developing other complications. Although Canver and Freier claimed that 14% of caecal diverticula will ultimately become inflamed [
14], they did not make it clear how they came to this conclusion. Perhaps the more important question is what we should do if a solitary caecal diverticulum is found incidentally at laparotomy. Langdon advised either excision or inversion [
15]. However, because the problem is uncommon this approach is not evidence-based.
This case report illustrates the importance of being aware of solitary caecal diverticulitis as a differential diagnosis of a patient with a right iliac fossa mass presenting with acute abdominal pain. Simple diverticulectomy with appendicectomy may be adequate if the diagnosis is made with confidence. Right hemicolectomy is advisable if the diagnosis is uncertain or the inflammation is extensive.