RADIOLOGY: GASTROINTESTINAL: GI: Case# 32896: SYNCHONOUS COLON AND RENAL CELL CA. This is an 82-year-old female with a history of breast cancer from 1989, with a right mastectomy. The patient has complained of constipation for three months. A colonoscopy performed 8/6/95, revealed a mass in the proximal descending colon, and an intraluminal stent was placed. The patient also complains of left hip pain. A mesh-stent is noted in the descending colon with a thickened bowel wall surrounding it. A large mass is noted with necrotic/cystic areas, measuring 6.5 x 8.0 x 10.0 cm, extending from the lower pole of the left kidney. This mass appears to be impinging on the descending colon. The descending colon surrounding the stent appears thickened and inflamed. A soft tissue mass is noted surrounding the left inferior pubic ramus, the left acetabulum, and the left iliac bone with bony destruction noted. The femoral head and neck appear surrounded by the mass but do not exhibit any bony destruction. A small pleural effusion is noted to the right lung base. The liver appears free of lesions. A 2.0 cm area of low attenuation is noted to the left kidney, consistent with renal cyst. Atherosclerotic calcific changes are noted to the descending aorta and common iliac arteries. The pancreas is normal. The adrenals are normal. No lymphadenopathy is noted. Colorectal adenocarcinoma is one of the most common neoplasms encountered in the affluent countries of the Western world. The disease exhibits a peak age incidence in the sixth and seventh decades. It is associated with increased serum concentration of carcinoembryonic antigen (CEA). Predisposing factors for colorectal cancer include adenomatous polyps, inherited multiple polyposis syndromes, long-standing ulcerative colitis, close relatives with colon cancer, and a low fiber, high animal fat diet. Colorectal cancer varies in gross presentation according to the region of the colon involved. Carcinoma of the rectosigmoid colon usually presents in an annular manner, often producing early bowel obstruction. Carcinoma of the right colon, however, usually does not obstruct early and frequently presents with iron deficiency anemia secondary to chronic blood loss. Colon cancer spreads by direct extension due to penetration of the colon wall, lymphatic drainage to regional nodes, through the portal system to the liver, and intraperitoneal seeding. Although barium enemas and colonoscopy are the primary methods used to initially diagnose colorectal cancer, CT is an excellent procedure for the detection of recurrence. CT findings of colon cancer include focal lobulated soft tissue mass in the colon, localized thickening of greater than 5 mm of the bowel wall, irregular lumen surface, extension of linear soft tissue densities or discrete mass into pericolic fat or adjacent organs, regional adenopathy, and liver metastases. Soft tissue masses visualized within the peritoneal cavity may signify metastases or recurrence of the cancer. Calcification in the primary tumor can be seen with mucinous adenocarcinoma. 85% of renal neoplasms are renal cell carcinomas, most commonly occurring in men, at ages 50-70, and usually involving one kidney. Only 2% are bilateral. Metastases are present at the time of diagnosis in 40% of cases. Since surgery is the only cure, early detection and accurate staging are important. The most common CT finding is a solid mass although low density areas due to hemorrhage or necrosis may be present. Cystic and multicystic forms may be seen. Stippled central or "eggshell" peripheral calcifications are seen in 10%. These tumors are usually hypervascular which may be evidenced by the presence of tortuous vessels in the perirenal fat. Tumor growth into the renal vein occurs in 30% of the time and into the inferior vena cava 5-10%. Venous invasion does not preclude surgical resection, but its identification is crucial to surgical planning. Renal cell carcinomas may spread locally to perirenal fat and adjacent organs. This is seen as strand or nodules of low density. Enlargement of renal hilar, pericaval, and periaortic nodes to 15mm or more indicates lymphatic spread. Hematogenous spread to the lung, bone, liver, adrenals, and the opposite kidney may occur. Distant metastases occasionally disappear with the removal of the primary tumor. Late appearance of metastases as long as 20 years following "cure" is also seen.