Piyush Joshi
BACKGROUND Colorectal carcinomas can broadly be classified as either non-mucinous or mucinous. Usually, mucinous adenocarcinomas present at a more advanced stage, have more aggressive local spread and have an increased incidence of lymph node involvement. Those cancers occurring in the rectum are considered more aggressive and require careful planning for treatment. Screening Computed Tomography (CT) is widely used for the initial evaluation of these tumours. The aim of the study is to retrospectively analyse the CT images of rectal adenocarcinomas and suggest parameters to aid differentiation of mucinous and non-mucinous tumours. MATERIALS AND METHODS The CT images of 24 cases of mucinous and 26 cases of non-mucinous adenocarcinoma were retrospectively reviewed and evaluated for parameters like morphology, wall thickness, size, pattern and degree of enhancement and the presence or absence of calcification. Also, evaluated was involvement of adjacent structures, lymph nodes and distant metastases. RESULTS All the parameters were analysed for significance using the chi-square test. Mucinous adenocarcinomas of the rectum showed a greater propensity for eccentric bowel thickening, heterogenous enhancement and calcification with a p value less than 0.05. Heterogenous enhancement showed the greatest sensitivity (75%) and calcification the greatest specificity (83.3%). The other parameters did not show any difference between the two groups. CONCLUSION CT features most likely to suggest rectal mucinous carcinoma are heterogenous contrast enhancement, eccentric wall thickening and intratumoural calcification. As mucinous carcinomas follow an aggressive course, if a diagnosis of mucinous carcinoma of the rectum can be suggested on the staging CT, it may influence patient management.
