To evaluate the value of routine ultrasound and contrast-enhanced ultrasound (CEUS) in differential diagnosis of benign and malignant lymph nodes in the upper abdomen after liver transplantation.

Clinical data of 70 patients with lymph node enlargement in the upper abdomen after liver transplantation who received routine ultrasound and CEUS simultaneously in the Third Affiliated Hospital of Sun Yat-sen University from January 2008 to November 2021 were retrospectively analyzed. Among them, 62 patients were male and 8 female, aged (48±11) years on average. The informed consents of all patients were exempted and the local ethical committee approval was received. According to CT, MRI, PET-CT and pathological diagnosis, 41 patients were diagnosed with benign lymph nodes (benign group) and 29 patients with malignant lymph nodes (malignant group). Routine ultrasound and CEUS features of benign and malignant lymph nodes in the upper abdomen after liver transplantation were analyzed. The diameter of lymph nodes between two groups was compared by t test. The rate comparison was performed by Chi-square test or Fisher's exact test.

Routine ultrasound showed that the percentage of patients with multiple malignant lymph nodes was 100% (29/29), and 56% (23/41) for benign lymph nodes, and the difference was statistically significant (P<0.05). The maximum and minimum diameters of lymph nodes in the malignant group were (33±13) and (21±9) mm, and (16±4) and (11±4) mm in the benign group, and the differences were statistically significant (t=7.754, 6.648; P<0.05). In the malignant group, the lymph nodes had unclear margins and irregular morphology and complicated with intrahepatic space-occupying lesions, which accounted for 24%(7/29), 14%(4/29) and 52%(15/29), and 0 in the benign group, the differences were statistically significant (P<0.05). In the malignant group, color blood flow signal was observed in 28%(8/29), and 7%(3/41) in the benign group, and the difference was statistically significant (χ²=3.850, P<0.05). CEUS showed that the perfusion patterns of uniform enhancement, uneven enhancement and thick-ring enhancement were seen in 4, 10 and 15 cases in the malignant group, and 30, 11 and 0 cases in the benign group, and the differences were statistically significant (P<0.05).

After liver transplantation, malignant lymph nodes in the upper abdomen are mainly large, featuring unclear margins and visible blood flow signals, primarily complicated with intrahepatic space-occupying lesions. CEUS shows uneven enhancement and thick-ring enhancement. Ultrasound can be employed as an effective imaging approach for auxiliary diagnosis and monitoring of upper abdominal lymph nodes after liver transplantation.