BACKGROUND: Struma ovarii is a rare ovarian teratoma with non-specific clinical presentation that can mimic malignancy, especially when combined with the presence of ascites. Since the surgical procedures performed for benign and malignant tumors are quite different, pre-operative differential diagnosis is key. In this case report we compare the levels of biomarkers CA 125 and HE4 in the differential diagnosis of a suspicious ovarian tumor.

CASE REPORT: A 75-year-old woman with a palpable mass at the left adnexa, ascites, and high levels of CA 125, underwent a subtotal abdominal hysterectomy and bilateral salpingo-oophorectomy. Histology reported benign struma ovarii.

CONCLUSIONS: Even though transvaginal ultrasound and CA 125 levels suggested malignancy, HE4 measurements correctly diagnosed benignity. 

Keywords: Biomarkers, Tumor - blood, CA-125 Antigen - blood, Diagnosis, Differential, Endosonography - methods, Follow-Up Studies, Hysterectomy - methods, Laparoscopy, Magnetic Resonance Imaging, Ovarian Neoplasms - surgery, Proteins - metabolism, Struma Ovarii - surgery, Tomography, X-Ray Computed, Vagina