Natural History of Indeterminate Liver Nodules in Patients With Advanced Liver Disease: A Multicenter Retrospective Cohort Study.

Introduction: Indeterminate liver nodules (ILNs) are frequently encountered on diagnostic imaging after positive hepatocellular carcinoma (HCC) surveillance results, but their natural history remains unclear.

Methods: We conducted a multicenter retrospective cohort study among patients with ≥1 newly detected LI-RADS 3 (LR-3) lesion ≥1 cm or LI-RADS 4 (LR-4) lesion of any size (per LI-RADS v2018) between January 2018 and December 2019. Patients were followed with repeat imaging at each site per institutional standard of care. Multivariable Fine-Gray models were used to evaluate associations between potential risk factors and patient-level time-to-HCC diagnosis, with death and liver transplantation as competing risks.

Results: Of 307 patients with ILNs, 208 had LR-3 lesions, 83 had LR-4 lesions, and 16 had both LR-3 and LR-4 lesions. HCC incidence rates for patients with LR-3 and LR-4 lesions were 110 (95% CI 70-150) and 420 (95% CI 310-560) per 1,000 person-year, respectively. In multivariable analysis, incident HCC among patients with LR-3 lesions was associated with older age, thrombocytopenia (platelet count ≤150 ×10 9 /L), and elevated serum alpha-fetoprotein levels. Among those with LR-4 lesions, incident HCC was associated with a maximum lesion diameter >1 cm. Although most patients had follow-up computed tomography or magnetic resonance imaging, 13.7% had no follow-up imaging and another 14.3% had follow-up ultrasound only.

Discussion: ILNs have a high but variable risk of HCC, with 4-fold higher risk in patients with LR-4 lesions than those with LR-3 lesions, highlighting a need for accurate risk stratification tools and close follow-up in this population.