Objective To explore the expression level of plasma miR-21 and its diagnostic value in differentiating FNH from HCA and AFP negative HCC.

Methods A total of 223 patients from the Department of Liver Surgery, Zhongshan Hospital were recruited, including 61 patients with focal nodular hyperplasia (FNH), 20 patients with hepatocellular adenoma (HCA) and 142 patients with AFP negative hepatocellular carcinoma (HCC). All the diagnosis was pathologically confirmed and 100 patients without liver mass were enrolled as baseline control. The preoperative plasma of all the patients was obtained and the expression of miR-21 was detected by quantitative transcription-polymerase chain reaction (qRT-PCR). The area under the receiver operating characteristic curve (AUC) was adopted to evaluate the accuracy of plasma miR-21 in differentiating FNH from HCA and AFP negative HCC.

Results The level of plasma miR-21 in FNH patients was 0.88 times higher than that in controls without liver mass (P=0.103), but significantly lower than that in HCA patients (P < 0.001, FC=0.49) and AFP negative HCC patients (P < 0.001, fold change, FC=0.41). The AUC of miR-21 for distinguishing FNH from AFP negative HCC was 0.914 (specificity: 75.4%; sensitivity: 92.3%), the AUC for distinguishing FNH from HCA was 0.806 (specificity: 50.8%; sensitivity: 100%) and the AUC for distinguishing patients requiring surgical treatment (HCC and HCA) from patients need not surgical resection (FNH) was 0.900 (specificity: 75.4%; sensitivity: 88.9%). Of the 13 cases of FNH with equivocal preoperative imaging diagnosis, 10 cases could be accurately identified by hematological indicators.

Conclusions The expression of plasma miR-21 in AFP negative HCC patients and HCA patients is significantly higher than that in FNH patients, which could be used as a powerful supplement of imaging diagnosis for FNH.