Inflammatory process in lower left abdomen on superior margin of proximal sigmoid colon?

Answer 1

The term diverticulitis represents a spectrum of inflammatory changes that ranges from localized subclinical inflammation to generalized peritonitis, with free perforation (Answers.com). In turn, this leads to hyperplasia of the lymphoid tissue within the mucosa at the base of the diverticulum, one of the earliest signs of diverticulitis. Inflammation usually begins at the apex of the diverticulum and seldom involves the neck or mucosa proximal to the neck. However, there is active inflammation of the pericolic and mesenteric fat, with peridiverticular abscess formation. These peridiverticular abscesses often involve areas of subserosa and are closely related to the outer aspect of the muscularis propria; they can spread circumferentially and longitudinally and may be responsible for the pathologic picture of diverticular colitis. Longitudinal tracking, especially, may result in fissuring, along with the lymphoid aggregates, which resembles the distinctive feature of colonic colitis in Crohn's disease. Answers.comThis may cause misinterpretation of the pathologic study of the specimen. Therefore, the differential diagnosis of these two conditions in terms of pathologic interpretation of the resected specimen is important. Persistent localized inflammation after diverticular rupture results in a phlegmon, a thickened, firm segment of bowel wall, which ultimately may manifest as acute or subacute large bowel obstruction. If left untreated or treated inadequately, it may result in extensive fibrosis around the affected segment of the colon, giving it a mass appearance indistinguishable macroscopically from that of a neoplasm.

Another pathologic entity that may be encountered during progression of the disease, with recurrent attacks of diverticulitis, is the formation of a localized abscess with chronic inflammation and involvement of other neighboring luminal organs, such as the bladder, small and large bowel loops, uterus, and vagina. Fistulae may develop within this contained area, between involved segment(s) of colon and these organs. Fistulae occur in 2.4% to 20% of cases; 65% of these fistulae are colovesical and 20% are colovaginal fistulae. Answers.com