CT of patients with right-sided colon cancer and distal ileal thickening

OBJECTIVE. The purpose of this study was to analyze the incidence and prima ry causes of distal ileal wall thickening in 131 patients with right-sided colon cancer. SUBJECTS AND METHODS. During a 2-year period, 131 patients underwent surgic al resection for right-sided colon cancer. Of these patients, we analyzed 1 3 who had distal ileal wall thickening on CT before surgery and also had th e cause determined at pathology. CT findings were analyzed with regard to t he morphologic features of colonic tumors, bowel wall involvement patterns of the distal ileum, and changes in the pericolic space. RESULTS. Distal ileal wall thickening occurred in 13 (10%) of the 131 patie nts who had right-sided colon cancer. Three patients had polypoid colon can cer, whereas the other 10 had infiltrative colon cancer. The mean thickness of the involved colonic segments was 1.6 cm (range, 1.0-2.2 cm) with a mea n length of 5.2 cm (range, 2.5-10.0 cm). Pericolic infiltration was mild in six patients and moderate in four patients. The mean length and thickness of the affected ileal segments were 3.2 cm (range, 1.5-6.0 cm) and 1.1 cm ( range, 0.7-2.0 cm), respectively. On histopathologic examination, neoplasti c processes involved the distal ileum in nine (69%) of the 13 patients. Thi s involvement was caused by either direct tumor invasion in seven patients or lymphatic spl ead in two. In four patients (31%), nonneoplastic processe s with edema and congestion involved the distal ileum. CONCLUSION. The distal ileum may be abnormally thickened in about 10% of pa tients with right-sided colon cancer; this thickening results from turner e xtension (69%) or a nontumorous process (31%).