Radiographic evidence of thymic involution in hepatocellular carcinoma: a propensity score-matched study in viral cirrhosis

Purpose Adult thymic involution has been implicated in impaired antitumor immunity, but whether hepatocellular carcinoma (HCC) is associated with structural thymic involution in humans remains unclear. This study evaluated parameters of thymic CT imaging in compensated liver viral cirrhotic patients with or without concomitant HCC. Patients and methods Patients with liver cirrhosis, with or without concomitant HCC, diagnosed between January 2016 and December 2022 were retrospectively screened. To minimize confounding from liver disease background, all patients were restricted to Child-Pugh class A cirrhosis of viral etiology. CT-derived thymic parameters, including anteroposterior and transverse diameters, left/right and overall bilateral lobe length and thickness, and CT attenuation, were measured using the Thymic Measurement and Analysis Program (ThyMAP). Propensity score matching (PSM) was performed to balance age, sex, hepatitis virus infection status, and Child-Pugh score. Sex-stratified and Barcelona Clinic Liver Cancer (BCLC) stage-stratified analyses were also conducted. Results A total of 121 patients with cirrhosis without HCC and 223 patients with cirrhosis-related HCC were included. Before PSM, patients with HCC had significantly smaller anteroposterior diameter, right lobe length, overall bilateral lobe length, left lobe thickness, right lobe thickness, and overall bilateral lobe thickness, compared with those without HCC. After PSM, 115 matched pairs were generated, and all measured thymic dimensions were significantly reduced in the HCC group. CT attenuation did not differ significantly before or after PSM. In sex-stratified analyses, significant reductions in several thymic dimensions were observed among male patients, whereas no significant differences were detected among female patients. Among patients with HCC, thymic parameters did not differ significantly between BCLC stages 0–A and B–C. Conclusion In patients with compensated viral cirrhosis, HCC occurrence is associated with reduced CT-derived thymic dimensions, but not CT attenuation. This association is more pronounced in male patients and appears related to HCC presence rather than BCLC stage progression.