Background: Benign struma ovarii (SO) with synchronous ascites and elevated CA125 level is extremely rare that the incidence, clinical characteristics, and risk factors remain unclear.
Methods: We conducted a retrospective study of patients with SO treated in our hospital between 1980 and 2022. Logistic regression was used to identify potential risk factors for SO patients presenting with ascites and elevated CA125 levels. The receiver operating characteristic (ROC) curve was used to evaluate the predictive performance of the identified risk factors.
Results: A total of 21 patients with synchronous ascites and elevated CA125 levels were identified in 229 patients with SO, the crude incidence rate was 9.17%, and four patients (1.75%) had pseudo-Meigs' syndrome. Ascites were completely involuted within 1 month postoperatively and the serum CA125 level decreased to normal between 3 d and 6 weeks after surgery. Multivariate logistic regression showed that age ≥49 years (OR 3.71, 95% CI 1.29 - 10.64, p = 0.015), tumor size ≥10.0 cm (OR 8.79, 95% CI 3.05 - 25.35, p < 0.001), and proliferative SO (OR 11.16, 95% CI 3.01 - 41.47, p < 0.001) were the independent risk factors for patients presenting ascites and elevated CA 125 level. The ROC curve revealed that the predictive performance for age and tumor size was unsatisfactory with an area under the curve (AUC) was 0.646 and 0.682, respectively. Linear regression demonstrated that the serum CA125 level has a moderate positive correlation with the volume of ascites (log2CA125 = 0.6272*log2ascites + 2.099, p = 0.0001, R2 = 0.5576).
Conclusions: Less than one-tenth of patients with SO would present ascites and elevated CA125 levels, while age ≥49 years, tumor sizes ≥10 cm, and the presence of proliferative SO were the risk factors.
Keywords: CA125 level; Struma ovarii; ascites; clinical characteristics; predictors.