RATIONALE AND OBJECTIVES: We investigated whether the peritumoral enhancement feature can aid in discriminating hepatocellular carcinoma (HCC) from intrahepatic cholangiocarcinoma (ICC) in contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System M (LR-M). MATERIALS AND METHODS: Between May 2018 and July 2024, 147 LR-M and 320 LR-5. lesions with pathologically confirmed HCC and ICC diagnoses after CEUS were examined. We evaluated the diagnostic efficacy of HCC with different diameters (≤3, 3-5, and 5-7cm) in the LR-M by peritumoral enhancement. We analysed the correlation between pathological perilesional hepatic sinusoid vessels and perilesional enhancement on CEUS in LR-M. The diagnostic performance of LR-5 with and without perilesional enhancement was evaluated. RESULTS: There were 93/107 HCC lesions and 1/40 ICC lesion with perilesional hepatic sinusoid vessels in LR-M. CEUS revealed perilesional enhancement in 81.31% (87/107) of HCC lesions and 10.00% (4/40) of ICC lesions. There was a correlation between perilesional hepatic sinusoid vessel and perilesional enhancement with correlation coefficients of 0.738. The diagnostic efficacy of 5-7cm lesions was the best, and the sensitivity, specificity, accuracy, and AUC were 0.900, 0.864, 0.885, and 0.882. After perilesional enhancement was added to LR-5, 91 cases of HCC in LR-M were adjusted into LR-5. The adjusted diagnostic efficacy was significantly improved. CONCLUSION: Perilesional enhancement on CEUS correlates with perilesional hepatic sinusoid vessel. Perilesional enhancement is a valuable feature for distinguishing HCC and ICC and could be added as a feature in CEUS LI-RADS.