BACKGROUND: Paraovarian cysts are common and are generally benign; however, they are frequently misdiagnosed as being of ovarian origin. Conversely, paraovarian tumors of borderline malignancy are extremely rare. Especially, no cases of spontaneous rupture have been reported, and all previous reports had normal serum carbohydrate antigen (CA) 125 level. As for imaging findings, the presence of papillary projections in the lumen of paraovarian tumors does not always indicate malignancy or benignancy, which makes the preoperative distinction difficult.

CASE REPORT: We report a case involving a 22-year-old Asian woman with a spontaneously ruptured paraovarian tumor of borderline malignancy. The serum CA125 concentration was extremely elevated, at 28,831 U/mL. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated a collapsed unilocular cystic lesion with multiple papillary projections. On MRI, the papillary projections showed two different patterns, which corresponded to the pathological findings.

CONCLUSIONS: Ruptured paraovarian tumors of borderline malignancy may show extremely high serum CA125 values. Furthermore, specific MRI findings may be useful in evaluating the malignancy of paraovarian tumors.

Keywords: CA-125 Antigen, Magnetic Resonance Imaging, Parovarian Cyst, Rupture, Spontaneous