A giant colonic diverticulum presenting as a 'phantom mass': a case report

Diverticulosis coli is the most common disease of the colon in Western countries. Giant colonic diverticulum, defined as a colonic diverticulum measuring 4 cm in size or larger, represents an unusual manifestation of this common clinical entity.

A 68-year-old Caucasian British woman with a history of intermittent lower abdominal mass, leg swelling and focal neurological symptoms underwent extensive non-diagnostic investigations over a significant period under a number of disciplines. The reason for a diagnosis being elusive in part related to the fact that the mass was never found on clinical and ultrasound examination. As a result, the patient's validity was questioned. Ultimately, this 'phantom-mass' was diagnosed as a giant colonic diverticulum causing intermittent compression of the iliac vein and obturator nerve.

Intermittent compression of the iliac vein and the obturator nerve by a colonic diverticulum has not previously been reported. A giant colonic diverticulum presenting as an intermittent mass is very rare. This case also illustrates two factors. First, the patient is often right. Second, the optimal mode of investigation for any proven or described abdominal mass with referred symptoms is cross-sectional imaging, typically a computed tomography scan, irrespective whether the mass or symptoms are constant or intermittent.