Diverticular disease represents a significant disease burden in the Western world with an overall incidence of  33-66% (1). Its prevalence is higher in people older than 80 years of age (65%) and in females. Most patients are usually asymptomatic and about 15% evolve to diverticulitis. Only 5-15% of patients with diverticulitis present with bleeding (2). Diverticular disease most commonly involves the sigmoid colon (95% of all cases). The size of each diverticulum usually varies between 2 mm and 2 cm, although rarely they can increase their size more than 10 times (3). Giant colonic diverticulum (GCD) defined as a diverticulum with a maximum diameter larger than 4 cm, is a rare condition first described by Bovine and Bonte in 1946. Few years later, in 1953, Hughes and Green reported the first radiologic diagnosis (4). 

GCD is an uncommon manifestation of the colonic diverticular diasease. The pathogenesis of GCD is unclear, and one of the accepted teories relates to a ball-valve mechanism by wich gas enters, but is unable to leave the diverticulum. In most cases, the maximum diameter of a GCD ranges between 4 and 9 cm; however, it has been described diverticula with diameters as large as 40 cm (5).  Clinical findings can vary from an asymptomatic abdominal mass to an incidental finding on imaging studies (6). The most common symptom is vague abdominal pain, which is present in approximately 70% of patients (5)(6). Other frequent symptoms include: diarrhea, constipation, fever, nausea, vomiting, rectorrhagia and enterorrhagia.

Diagnosis of GCD relies mainly on imaging findings due to its non-specific clinical presentation (5)(6). Conventional abdominal radiographs, barium enema, abdominal Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) studies are usually diagnostic; on the contrary, colonoscopy is usually not (7).  Surgery is the recommended treatment of GCD due to the high risk of complications, which can affect 15% - 35% of patients. Complications include perforation, urinary obstruction, and abscess or fistula formation. In general, colectomy is the treatment of choice; when the adjacent bowel is healthy, a simple diverticulectomy can be performed (8).

Case presentation

A 59 year-old male with history of diverticular disease for 10 years and two-vessel coronary disease (in 2001 and 2005 required coronary stenting due to acute myocardial infarction), consulted in October 2014 to the emergency room presenting an episode of enterorrhagia. A colonoscopy performed during the initial visit showed multiple diverticula and a giant diverticulum located at 28 cm from the anal margin. The giant diverticulum presented an abraded surface and a small ulcer covered with hematin. A diagnosis of left colon diverticular disease and a giant sigmoid diverticulum with signs of recent bleeding was made (Figure 1). Due of the patient’s cardiovascular comorbidities (a recent myocardial infarction that required management with two coronary stents), and because the bleeding was succesfully  treated with epinephrine injections (1:20,000 in saline) in four quadrants, the patient did not receive surgical treatment.

Figure 1. A, B. Colonoscopy images show the giant diverticulum in sigmoid colon, with signs of recent bleeding (arrows).

One year later, on April 2015, the patient revisited the emergency room complaining of abundant haematochezia, associated with lower abdominal pain, fatigue, weakness and decreased appetite, symptoms which lasted for 15 hours. The patient denied fever, weight loss, nausea or vomiting. Physical examination demostrated dry oral mucosa, mucocutaneous pallor, no abdominal pain, non-palpable masses or organ enlargement, and adequate peristalsis. The patient was afebrile but tachycardic (118 heart beats per minute). Laboratory tests showed leukocytosis (12.1x10⁹/L), low hemoglobin levels (11.6g/dl), low hematocrit levels (36.6%) and a normal platelet count (245000/mm³).

A colonoscopy performed during the second visit, showed signs of active bleeding which was controlled effectively with sclerotherapy, and a giant sigmoid diverticulum with local signs of inflammation (Figure 2).

Figure 2. Colonoscopy images demonstrate the cecum (A) and the edematous giant diverticulum with granulation tissue (arrows in B and C).

The patient required transfusion of one unit of red blood cells and a laparoscopic left colectomy was suscesfully performed due to the high risk of perforation, with prior preoperative assessment of the cardiologist. Gross examination of the surgical specimen revealed a 12 x 10 cm giant sigmoid diverticulum with a mouth of 2 cm , and a segment of the left colon which measured 16 x 5 cm (Figure 3). The giant diverticulum presented a purple outer surface and contained multiple saccular formations, one of them with cystic dilatation (9 x 6 cm with a wall of 0.6 cm). A violet surface covered the mucosa. No more lesions were recognized. Indurated fibrous areas were observed in the mesocolon.

Figure 3: A, B. Surgical specimen showing the giant diverticulum (thin arrow). The localization of the diverticulum in the left colon is appreciated in B (thick arrow).

The definite diagnoses based on the macroscopic and histopathological findings, included: a) complicated diverticular disease with mucosal ulceration and associated signs of chronic and acute inflammation without perforation; b) an ulcerated GCD with extensive fibrosis and granulation tissue of the wall; c) mild signs of acute inflammation at the section margins.

Discussion

Diverticulosis of the colon is a fairly common disease, but a solitary giant diverticulum is relatively rare. A total of 187 cases on giant colonic diverticulum have been reported in the literature until 2015. It is characterized by the presence of a diverticulum exceeding 4 cm in size, with approximately 90% of the cases involving the sigmoid colon. From a histological point of view, giant diverticula are classified into three types: type 1 (22%) with a diverticular wall composed of mucosal and muscular layers, type 2 (66%) with inflammatory infiltrate (as in our case), and type 3 (12%) affecting all layers of the colonic wall (6-8).

For the literature review of published case reports concerning giant colonic diverticulum (GCD), we searched Embase and Pubmed databases using the following MESH search headings: “giant colonic diverticulum”; “giant sigmoid diverticulum”. In this search we found a systematic review of the literature published by Nigri et al. (9) in January 2015 of 166 cases of GCD; besides, we found another 21 different cases that were not included in this review (see Table 1).

Table 1: Characteristics of 21 cases of Giant Colonic Diverticulum found in the literature (case reports until 2016)

*CT:  Computed Tomography

**MRI: Magnetic Resonance Imaging

***GCD: Giant colonic diverticulum