Loss of NPM2 Expression Is A Potential Immunohistochemical Marker for Malignant Peritoneal Mesothelioma : A Single-Center Study of 92 Cases

Background: To explore the correlation between the expression level of nucleoplasmin 2 (NPM2) and the main clinicopathological characteristics and prognosis of malignant peritoneal mesothelioma (MPM). Methods Ninety-two postoperative specimens from MPM patients following cytoreductive surgery and hyperthermic intraperitoneal chemotherapy were collected. Postoperative specimens were stained with immunohistochemistry. The expression level of NPM2 was quantitatively analyzed by QuPath-0.3.2 software. Univariate and multivariate analyses were conducted to investigate the correlation between NPM2 expression and other conventional clinicopathological characteristics. Results Among the 92 MPM patients, there were 47 males (48.9%) and 45 females (51.1%), with a median age of 56 (range: 24–73). There were 70 (76.0%) cases with loss of NPM2 protein expression, 11 (12.0%) cases with low expression, and 11 (12.0%) cases with high expression. Univariate analysis showed that NPM2 protein expression level (negative vs. low expression vs. high expression) was negatively correlated with the following three clinicopathological factors: completeness of cytoreduction (CC) score, vascular tumor emboli, serious adverse events (SAEs) (all P  < 0.05). Multivariate analysis showed that NPM2 protein expression level (negative vs. low expression vs. high expression) was independently negatively correlated with the following two clinicopathological factors: CC score [odds ratio (OR) = 0.317, 95%CI: 0.317–0.959, P  = 0.042], vascular tumor emboli (OR = 0.092, 95%CI = 0.011–0.770, P  = 0.028). Survival analysis showed that loss of NPM2 protein expression (negative vs. positive) was associated with poor prognosis of MPM. Conclusions Loss of NPM2 expression is a potential immunohistochemical marker for MPM.