Diagnostic Pitfalls of Ruptured Ovarian Serous Borderline Tumors by Minor Trauma: A Case Report

A 54-year-old woman visited our hospital due to abdominal pain after a fall. Computed tomography (CT) showed abdominal distention, massive ascites, and membranous structures of unknown origin, but no mass lesions in the abdomen. Blood tests showed increases in CRP to 31 mg/dL, CA19-9 to 2100 U/mL, and CA125 to 10020 U/mL. Ascitic fluid analysis showed no malignant cells, an increased cell count, and an elevated adenosine deaminase level of 174 U/L. Positron emission tomography showed no avid accumulation of fluorodeoxyglucose in the abdomen. We, therefore, drained the ascites for symptom relief, which unintentionally resulted in marked decreases in CA19-9 and CA125 to 221 U/mL and 1802 U/mL, respectively. Thereafter, an exploratory laparotomy showed a large amount of dirty ascites, abscess, fibrin clots, and no ovarian tumors. A cell block analysis of the ascites taken during the operation showed positivity of CK7, ER, and PAX8 and negativity of CK20 and CDX-2, leading to the diagnosis of a possible uterine or ovarian tumor. The second operation, six weeks after the exploratory laparotomy, showed multiple peritoneal implant-like lesions and a large ovarian tumor with a capsule, which released massive fluid of 6.6 L due to the capsule rupture during the operative procedures. Postoperative pathological study showed that the ovarian tumor was a unilocular cystic tumor with no solid components, had partially thickened cyst walls with hyalinization, and scant presumed invasion of atypical cells in a tubular fashion, finally making the diagnosis of ovarian serous borderline tumor (SBT). The patient recovered uneventfully and has been well without any recurrence for two years. Emergency physicians should note that ovarian SBTs can rupture even with minor trauma and cause underdiagnosis due to the lack of evident solid parts in the tumor.