It has been reported that inflammatory polyposis is found in approximately 10–20% of patients with ulcerative colitis [1
], but also occasionally occurs in Crohn's disease [3
]. An inflammatory polyposis may rarely grow to a giant size, forming varying shapes such as a mass-like, worm-like appearance and is referred to as localized giant inflammatory polyposis [5
]. An arbitrary criterion of 1.5 cm or greater in size has been accepted for giant polyposis [5
]. This lesion usually consists of segmental and circumferential colonic lesions [8
]. It is more likely to occur in patients in a quiescent state in Crohn's disease, although it may be found in both the active and quiescent phases of IBD [7
]. Our patient had been in a quiescent phase of Crohn's disease on medical treatment for the past 10 years. Kelly et al. previously reviewed 53 cases of localized giant inflammatory polyposis with IBD [8
]. In their report, 63% of cases had Crohn's disease and 37% had ulcerative colitis as underlying disease. The most frequent sites of colonic involvement were the transverse colon, followed by the sigmoid, descending colon, and cecum. It is recognized that inflammatory polyposis is a secondary product, resulting from mucosal regeneration after ulceration, whereas localized giant inflammatory polyposis appears to result from enlarged mucosal tags which are dragged along by the fecal stream and peristalsis [8
]. However, the factors responsible for the production remain largely unknown. Localized giant inflammatory polyposis does not cause any specific symptoms except clinical symptoms due to the underlying IBD, so conservative treatment is generally indicated. However, this lesion may occasionally cause severe complications such as colonic obstruction or intussusception due to a mass effect [4
]. 23–55% of patients with this lesion have complete or incomplete colonic obstruction [6
]. Thus, a patient with localized giant inflammatory polyposis should be followed up regularly by barium enema or colonoscopy. When these complications occur, surgery is usually necessary for treatment. In our case, it was considered that a group of giant polyps as well as thickened and sclerotic intestinal wall in the ileocecal portion was the source of the obstruction of the ileocecal orifice.
Radiologically or endoscopically, localized giant inflammatory polyposis is often mistaken for a neoplastic lesion due to variations in the appearance of the lesion. In some cases, excessive surgery is performed because of a misdiagnosis such as carcinoma [10
]. Because of this, the endoscopic biopsy specimen taken from the lesion was examined histologically to ensure a correct diagnosis. Magnifying endoscopy is useful for examining the histology of this disease [10
]. This technique is used because it can show the fine surface structure of the lesion and can distinguish neoplastic from non-neoplastic lesions to divide the pit patterns prior to histological examination. Localized giant inflammatory polyposis is generally regarded as a benign lesion [7
]. However, Kusunoki reported a case of occult cancer in localized giant inflammatory polyposis associated with ulcerative colitis [11
]. He suggested that this lesion might be a factor involved in carcinogenesis and one of the patterns of carcinoma development in ulcerative colitis. Because of this, an extensive pathological examination after the operation is also important.
We present a case of localized giant inflammatory polyposis of the ilececum associated with Crohn's disease. It is thought that this lesion typically requires no surgical treatment, unless it is accompanied by severe complications. However, clinicians should keep in mind that obstructions can develop and that a potential for malignancy exists.