M1 defines the presence of lymphadenopathy outside the central route of outflow and in the para-aortic site and the presence of distant metastasis. CT plays a major role also in M staging. In about 15% of cases rectal carcinoma shows on first diagnosis secondary liver localisation . It has a satisfactory sensitivity in the detection of hepatic metastatic lesions; in no contrast scans metastases appear as hypodense area. In sporadic cases these lesions may present small calcifications, typical of mucinous adenocarcinoma . In dynamic scanning (contrast bolus) in the arterial phase metastases show ring enhancement. In the late phase (10-15 min after bolus) the lesions tend to become hypodense with the adjacent parenchyma.
There is central enhancement in case of a central fibrotic or necrotic focus.
The detection of small metastatic hepatic lesions at surgery for rectal carcinoma is important because they may be resectable with consequent improvement of the patient's survival.
Adrenal metastases have also been observed in patients with rectal cancer. The findings of enlarged inhomogeneous or asymmetrical adrenal glands should be suggestive of secondary location . The finding of ascitic effusion into the peritoneal cavity is a sign of peritoneal metastatic spread .
Was this article helpful?