FROM THE ARCHIVES OF THE AFIP - COLORECTAL ADENOCARCINOMA - RADIOLOGIC-PATHOLOGICAL CORRELATION

Colorectal adenocarcinoma is extremely common and the second most comm on cause of cancer death in the United States. Almost all colorectal a denocarcinomas arise from tubular and villous adenomas, most likely th ose greater than 2 cm in size. Occasionally, however, carcinoma will a rise from areas of dysplasia of flat mucosa as in the case of inflamma tory bowel disease. The annular constricting lesion, the most common a ppearance of adenocarcinoma in the left side of the colon, is caused b y circumferential spread of tumor within the lymphatics of the inner c ircular layer of the muscularis propria. Fungating masses, manifesting with anemia or intussusception, are the most common appearance of ade nocarcinoma in the right side of the colon. Saddle lesions, ulcerating masses, and infiltration tumors are less common forms of growth. Muci nous adenocarcinoma may be recognized rarely by calcification and more commonly by the low attenuation of excessive pools of extracellular m ucin within the tumor. The degree of local spread and presence of lymp hatic or hematogenous metastases are best classified by the TNM system , although the modified Dukes classification is frequently employed. L ocal disease is probably best assessed with endoscopic ultrasound. Cro ss-sectional imaging is most useful in the evaluation of advanced dise ase, recurrent disease, and associated complications, although the rol e of magnetic resonance imaging may expand with the introduction of en dorectal coils. Screening programs for adenomas and early carcinomas h ave the potential to decrease the mortality from this malignancy with appropriate removal of adenomas. The radiologist, with use of barium e nema studies, should be instrumental in initiating, participating in, and popularizing screening protocols for colon cancer.