The value of CT in rectal villous tumors

Computed tomography of 13 patients with villous rectal tumors was reviewed. Five tumors were benign, eight were malignant. All five benign lesions demonstrated homogeneous focal colonic wall thickening of less than 2 cm. Seven of the eight malignant lesions demonstrated focal colonic wall thickening greater than 2 cm. "Fronds," characterized by contrast within the interstices of the lesion, were seen in three malignant lesions. In the remaining five malignant lesions, three had a polypoid appearance, one had low attenuation regions, and one had focal rectal wall thickening. Computed tomography upstaged two carcinomas, downstaged two carcinomas, and accurately staged four carcinomas. Our experience shows (a) CT can demonstrate the classic fronds of villous tumors; (b) benign villous tumors tend to be less than 2 cm and are nonspecific in appearance; (c) biopsy is necessary to differentiate small malignant lesions from benign lesions; and (d) CT is inaccurate in staging local invasion of malignant villous tumors.