Appendiceal Orifice Inflammation Mimicking Submucosal Tumor on Roentgenogram in Ulcerative Colitis

Appendiceal orifice inflammation (AOI) is observed as skip lesion in distal ulcerative colitis (UC). The endoscopic frequency of AOI is reported to be 7.9% to 76% of distal colitis. UC is a relapsing and remitting disease and a morphological change of the large bowel occurs over time. Patient and physician can easily understand the shape of the whole large bowel not through endoscopic photograph but by roentgenogram of the bowel. Therefore, the authors undertake barium enema study when a diagnosis of UC is made. We have experienced a patient with proctitis in which an appendiceal submucosal tumor (SMT) was suspected on the roentgenogram but it was turned out to be a protruding lesion of AOI. A 16-year-old boy visited us with complaining of blood in his stool for the past 10 days. Sigmoidoscopy revealed mild diffuse inflammation. Crypt abscess was found in biopsy specimen. A diagnosis of UC, proctitis type, was made. A double contrast barium enema study revealed a defect shadow with a smooth surface, length 37 mm, height 12 mm, over the appendix. An appendiceal SMT was suspected. Abdominal ultrasonography and computed tomography were non-contributory. Colonoscopy revealed a spiral inflamed mucosa at the site of an appendiceal orifice. There was an inflammation in the cecum surrounding the orifice. Biopsy specimen of the appendiceal orifice showed inflammatory cells infiltration, goblet cell depletion, and cryptitis. The suspected SMT lesion was concluded to be AOI.