Poorly-differentiated colorectal neuroendocrine tumour: CT differentiation from well-differentiated neuroendocrine tumour and poorly-differentiated adenocarcinomas

The differentiation of poorly-differentiated neuroendocrine tumours (PD-NETs), well-differentiated NETs (WD-NETs), and adenocarcinomas (ADCs) is important due to different management options and prognoses. This study is to find the differential CT features of colorectal PD-NETs from WD-NETs and ADCs. CT features of 25 colorectal WD-NETs, 36 PD-NETs, and 36 ADCs were retrospectively reviewed. Significant variables were assessed using univariate and multivariate analyses. Receiver operating characteristics analysis determined the optimal cut-off value of tumour and lymph node (LN) size. Large size, rectum location, ulceroinfiltrative morphology without intact overlying mucosa, heterogeneous attenuation with necrosis, presence of ae >= 3 enlarged LNs, and metastasis were significant variables to differentiate PD-NETs from WD-NETs (P < 0.05). High attenuation on arterial phase, persistently high enhancement pattern, presence of >= 6 enlarged LNs, large LN size, and wash-in/wash-out enhancement pattern of liver metastasis were significant variables to differentiate PD-NETs from ADCs (P < 0.05). Compared to WD-NETs, colorectal PD-NETs are usually large, heterogeneous, and ulceroinfiltrative mass without intact overlying mucosa involving enlarged LNs and metastasis. High attenuation on arterial phase, presence of enlarged LNs with larger size and greater number, and wash-in/wash-out enhancement pattern of liver metastasis can be useful CT discriminators of PD-NETs from ADCs.