Outcome and CT differentiation of gallbladder neuroendocrine tumours from adenocarcinomas.

Objectives: To retrospectively investigate clinical outcome and differential CT features of gallbladder (GB) neuroendocrine tumours (NETs) from adenocarcinomas (ADCs).

Materials And Methods: Nineteen patients with poorly-differentiated (PD) NETs and 19 patients with PD ADCs were enrolled. Clinical outcome was compared by the Kaplan-Meier method. We assessed qualitative and quantitative CT features to identify significant differential CT features of PD NETs from ADCs using univariate and multivariate analyses. Receiver operating characteristic (ROC) analysis was used for quantitative CT features.

Results: PD NETs showed poorer prognosis with significantly shorter median survival days than ADCs (363 vs. 590 days, P = 0.03). On univariate analysis, NETs more frequently manifested as GB-replacing type and showed well-defined margins accompanied with intact overlying mucosa. On multivariate analysis, well-defined margin was the sole significant CT differentiator (odds ratio = 27.817, P = 0.045). Maximum size of hepatic and lymph node (LN) metastases was significantly larger in NETs (11.0 cm and 4.62 cm) than ADCs (2.40 cm and 2.41 cm). Areas under ROC curves for tumour-to-mucosa ratio, maximum size of hepatic and LN metastasis were 0.772, 0.932 and 0.919, respectively (P < 0.05).

Conclusion: GB PD NETs show poorer prognosis than ADCs. Well-defined margin, larger hepatic and LN metastases are useful CT differentiators of GB NETs from ADCs.

Key Points: • A well-defined margin is a useful CT differentiator of GB NETs from ADCs. • Hepatic and LN metastases are significantly larger in NETs than in ADCs. • Primary tumour and hepatic metastasis of NETs are more hyperattenuated than ADCs.