CT differentiation of mucinous and nonmucinous colorectal carcinoma

The purpose of this study was to evaluate the CT findings that can help differentiate mucinous from nonmucinous colorectal carcinoma.

CT scans of 86 patients with pathologically proven mucinous colorectal carcinoma were analyzed, and 105 consecutive patients with nonmucinous colorectal carcinoma were also included as a control group. CT findings were compared between the two groups with regard to the bowel involvement patterns; patterns of contrast enhancement; and presence or absence of bowel obstruction, intratumoral calcification, pericolic fat infiltration, and local tumor extension to adjacent organs. Statistical analyses were performed using the Student's t test and Pearson's chi-square test.

Compared with nonmucinous carcinoma, mucinous carcinoma showed more severe (2.41 +/- 1.19 cm vs 1.94 +/- 0.92 cm) (p = 0.004) and more eccentric (22% vs 8%) (p = 0.025) bowel-wall thickening. Heterogeneous contrast enhancement was more common in mucinous than in nonmucinous carcinoma (83% vs 53%) (p = 0.001). Mucinous carcinoma showed more areas with hypoattenuation (p = 0.001), and the solid portion of mucinous carcinoma showed less enhancement than that of nonmucinous carcinoma (p = 0.001). Presence of intratumoral calcification was more frequent in mucinous carcinoma (21% vs 5%) (p = 0.001). Heterogeneous enhancement showed the highest sensitivity (82.6%) but moderate specificity (55.9%) in diagnosing mucinous carcinoma. Tumors with four or more CT findings with a statistically significant difference were mostly mucinous carcinoma, and the specificity was 87%.

CT is useful in the differentiation of mucinous from nonmucinous colorectal carcinoma.