A Case of Giant Colonic Diverticulum

An 88-year-old man with a history of hypertension, coronary artery disease, atrial fibrillation, and hypothyroidism presented to his primary care physician complaining of malaise and a weight loss of 20 lbs over the past few months. His physical examination was unremarkable. Serum chemistries, however, revealed anemia-hematocrit, 28% (normal range, 41% - 51%)]. Abdominal CT revealed a 5- to 6-cm lesion in the pelvis suggestive of either a walled-off abscess or a diverticulum (Figure). After a surgical consultation, the patient was admitted to the hospital for further evaluation.

A colonoscopy found a sigmoid stricture and diverticulosis within the visualized portion of the sigmoid colon. Broad-spectrum antibiotics were initiated and a sigmoid colectomy was performed the following day. Surgical findings included a large sigmoid diverticulum surrounded by severe inflammation. Histologic analysis revealed a pseudocyst consisting of inflammatory tissue surrounding the sigmoid colon with a communication to the anti-mesenteric surface of the colon. The rectum was closed with a Hartmann pouch and an end-colostomy was placed. A diagnosis was made of giant colonic diverticulum (4 x 3 x 2.5 cm). After several weeks of rehabilitation at a skilled nursing facility, the patient was discharged. Our patient is currently 91 years of age, living at home, and his stoma is managed by a caregiver. He does have a moderate peristomal hernia but has declined surgical closure.

Discussion
Giant colonic diverticulum (GCD) is a rare and extreme manifestation on the continuum of diverticular disease. It was described in the early 1950s as a “solitary air cyst.”¹ Presentation can be acute, however, symptomatology most often follows an indolent course. Classification is based on size and histologic findings. GCDs are defined as lesions 4 cm or larger in diameter.² There are 2 histologic types. A type I GCD, as in this case, also called a pseudo diverticulum, is most likely associated with conventional diverticular disease and occurs when a contained perforation forms an air-filled pseudocapsule that continues to enlarge. Approximately 87% of GCDs are classified as Type I.³ A type II, or true diverticulum, contains all layers of bowel wall and structurally resembles a duplication cyst.⁴ True GCDs are rare and are thought to be congenital.  

Nearly all (~90%) of GCDs, regardless of type, are found within the sigmoid colon; 25% communicate with the lumen; and the majority occur on the anti-mesenteric side of the colon.^5,6 Most GCDs measure between 7 and 15 cm. As with diverticular disease, this usually affects patients in their 60’s and 70’s.⁷ Up to 70% of GCDs are palpable on examination.⁷ These patients can present acutely, but more often onset is insidious with gradual development of chronic pain.⁶

GCDs are detectable on abdominal x-ray and appear as large air-filled structures (the “balloon sign”). Diagnosis is most often based on CT findings, and CT imaging allows better visualization of surrounding structures.^7,8 CT with water soluble contrast may help detect communication with the colon. Colonoscopy may provide visualization of other lesions but adds little additional information about GCD.³

Initial management includes IV hydration, antibiotics, and analgesics. Unless contraindicated by medical comorbidities, surgical resection with or without primary anastamosis is indicated.^6,9 Selected cases of true diverticula may be adequately removed by diverticulectomy alone.^6,9

A palpable abdominal mass is usually an ominous finding. GCD, however, is a potentially curable condition that tends to occur in members of the age group often given a diagnosis of a malignancy. Therefore, aggressive work-up and early surgical intervention are warranted.
 
 

References:

References

1. Hughes WL, Greene RC: Solitary air cyst of peritoneal cavity. Arch Surg. 1953;74:931-936.

2. Nicholson Y, Angel LP, Caliendo, FC, Procaccino, JA. Giant colonic diverticula. Surgical Rounds. 2007:224-228.

3. Mehta, DC, Baum, JA, Dave, PB, Gumaste, VV. Giant sigmoid diverticulum: a report of two cases and endoscopic recognition. Am J Gastroenterol 1996;91:1269-1271.

4. Ryckman, FC, Glenn JD, Moazam F. Spontaneous perforation of a colonic duplication. Dis Colon Rectum. 1983;26:287-289.

5. Sagar, S. Giant solitary diverticulum of the transverse colon with diverticulosis. Br J Clin Pract. 1973;27:145-146.

6. Maresca L, Maresca C, Erickson E. Giant sigmoid diverticulum: a report of a case. Dis Colon Rectum. 1981;24:191-195.

7. Chaiyasate K, Yavuzer R, Mittal V. Giant sigmoid diverticulum. Surgery. 2006;139(2):276-277.

8. Rosenberg RF, Naidich JB. Plain film recognition of giant colonic diverticulum. Am J Gastroentero.l 1981;76:59-69.9. Al-Jurf AS, Foucar E. Uncommon features of giant colonic diverticula. Dis Colon Rectum. 1983;26:808-813.