Diverticulosis coli is the most common disease of the colon in Western countries; GCD represents an unusual manifestation of this common clinical entity [3
Histologically, there are three different types of GCD with similar clinical presentations [2
]. The first type is a pseudo-diverticulum which gradually increases in size; remnants of muscularis mucosa and muscularis propria may be found in its wall. In most cases, the mucosa is not completely intact. This type of GCD could be explained by the flap-valve or gas-forming organisms theories.
If no mucosal remnants are found, the GCD is considered inflammatory (type 2), which is actually a result of a local perforation of the mucosa with an abscess cavity that remains in contact with the lumen of the colon (organized abscess theory). The wall of this diverticulum contains reactive scar tissue only. The third type is a true diverticulum, in which the wall contains all of the layers of normal bowel (congenital duplication theory).
In this patient, the diverticulum gradually inflated because of a flap-valve action of the tiny opening from the bowel, allowing gas and debris to enter, but not escape, during periods of straining. The failure of barium to enter the GCD attests to the small size of the opening. The fact that this GCD could expand and shrink indicates that its wall had elastic properties. When fully expanded, it produced compressive symptoms.
Symptoms of GCD and their duration are variable; often the patient's complaint can be ascribed to the associated diverticulitis [4
]. A palpable abdominal mass in a patient with diverticulitis is almost invariably a paracolic inflammatory mass related to acute diverticulitis. Presentation of colonic diverticula as a palpable abdominal mass in the absence of acute diverticulitis is extremely rare [5
]. The intermittent appearance of a large painless mass in our patient was probably due to filling of the GCD with gas and faecal material whose expulsion led to the disappearance of the mass. The associated symptoms are related to pressure on the left iliac vein and the left obturator nerve.
Such a presentation of GCD as a longstanding non-inflammatory intermittent abdominal mass is distinctly unusual. Intermittent compression of the iliac vein or the obturator nerve as a presentation of GCD has not previously been reported.
Plain film diagnosis of GCD can be made in the presence of a persistent smooth-walled gas containing structure, 'balloon sign', adjacent to the colon with or without air fluid level [6
Diagnostic colonoscopy is not considered to be helpful [7
] except in cases with a large ostium where an incidental diagnosis of GCD is possible [8
]. The use of barium enema did not yield a positive diagnosis in this patient, although a communication with the colon can be demonstrated on contrast studies in 25% to 66% of GCD cases [7
Ultrasound examination does not seem to be helpful in detecting a non-complicated GCD [7
]. In our patient, we were falsely reassured by a normal ultrasound. Computerized tomography and magnetic resonance imaging are useful in defining the GCD and its relation to surrounding structures [9
]. The intermittent nature of this patient's symptoms made diagnosis difficult. Arguably, an earlier CT scan may have helped. The final diagnosis was only made when barium inspissated in the neck of the GCD and provoked local diverticulitis which merited immediate CT evaluation.