Quiet Before the Storm: Indolent Chronic Diverticulitis Mimicking Carcinoma

Abstract

Acute diverticulitis and chronic diverticulosis are common diagnoses in the Western world, with nearly 50% of adults over the age of 50 carrying the diagnosis of diverticulosis, and 10-25% of those patients going on to develop acute diverticulitis. However, the incidence and clinical presentation of indolent chronic diverticulitis is less understood. A 68-year-old male presents after an abnormal colonoscopy demonstrating hyperplastic polyps. A follow up flexible sigmoidoscopy demonstrated a long area of abnormal, erythematous and edematous mucosa with a mass-like area protruding into the lumen. A diagnosis of diverticulosis was made and abdominal computed tomography (CT) confirmed chronic changes associated with diverticulosis. One year after the initial colonoscopy, the patient presented with abdominal pain and loose stools. He was given ciprofloxacin and metronidazole to decrease inflammation. A repeat scope found severe diverticulosis in the sigmoid colon with an obstructive lesion and significant stenosis. A sigmoid stent was placed and the patient was scheduled for surgery. Resection of the sigmoid colon was performed with part of the bladder and ascending colon due to adherence to the colonic mass. Pathology revealed the mass to be consistent with acute and chronic inflammation, concerning for diverticulosis and acute diverticulitis, and negative for malignancy. There is a paucity of literature on chronic indolent diverticulitis as seen in this patient. Acute diverticulitis of the sigmoid colon often presents with leukocytosis, fever and left lower quadrant pain. Chronic diverticulitis instead presents with obstruction or constipation. Narrowing of the sigmoid develops over time as fibrosis, pericholic fat, and inflammation take the place of the normal colonic wall causing obstruction. CT remains the most sensitive imaging for diverticulitis, however radiographic findings make it difficult to distinguish between diverticulitis and colon cancer as they both have luminal narrowing and thickened bowel wall. In these cases, an inflammatory process may appear as an inflammatory mass. As compared to acute diverticulitis, which is treated conservatively, chronic diverticulitis is best treated with surgical resection. Interestingly, many of these patients are taken to surgery with the thought that the mass is malignant. Prognosis for these patients is dependent on progression of disease but resolution of obstruction can be expected with surgical resection.1478_A Figure 1. Endoscopic image of colonic diverticulitis mass.1478_B Figure 2. Endoscopic image of stent placed across sigmoid colon mass.