Epithelial Ovarian Tumor
The most likely diagnosis is epithelial ovarian tumor (Option C), specifically advanced-stage disease given the constellation of bilateral ovarian masses, ascites, pleural effusion, and elevated CA-125.
Clinical Presentation Matches Advanced Epithelial Ovarian Cancer
The patient's presentation is classic for advanced epithelial ovarian carcinoma (EOC):
- Symptoms of bloating, abdominal pain, and loss of appetite are the most frequent presenting complaints in advanced EOC 1
- Ascites and abdominal distension occur in advanced stage disease when peritoneal metastases are present 1
- Pleural effusion causing respiratory symptoms indicates stage IV disease with extension into pleural cavities 1
- Bilateral ovarian masses are characteristic of epithelial ovarian cancer, particularly high-grade serous carcinoma 1
CA-125 Elevation Strongly Supports Epithelial Origin
The CA-125 level of 95 U/mL is diagnostically significant:
- CA-125 is elevated in approximately 85% of patients with advanced epithelial ovarian cancer 1, 2
- CA-125 is the primary tumor marker for epithelial ovarian cancer, particularly serous carcinomas which account for 70% of epithelial cases 2
- While CA-125 can be elevated in benign conditions (endometriosis, ovarian cysts), the combination with bilateral masses, ascites, and pleural effusion makes malignancy far more likely 1, 2
Why Other Options Are Less Likely
Sex cord stromal tumors (Option A) are much less common and typically present differently:
- These tumors can cause Meigs' syndrome (benign ovarian fibroma with ascites and pleural effusion) 3, 4, 5
- However, Meigs' syndrome typically involves unilateral or bilateral fibromas/fibrothecomas, not the bilateral malignant-appearing masses described 4, 5
- While CA-125 can be markedly elevated in Meigs' syndrome, this is a diagnosis of exclusion only after ruling out epithelial ovarian cancer 6
Ovarian germ cell tumors (Option B) are unlikely because:
- These occur predominantly in younger women and would typically have elevated AFP and β-hCG, not primarily CA-125 7
- The clinical presentation doesn't match typical germ cell tumor patterns
Gonadoblastoma (Option D) is extremely rare and:
- Occurs almost exclusively in patients with gonadal dysgenesis
- Would not present with this clinical picture
Critical Diagnostic Pitfall to Avoid
Do not assume Meigs' syndrome based on elevated CA-125 alone. While benign sex cord stromal tumors can present with ascites, pleural effusion, and markedly elevated CA-125 (even >1000 U/mL), this mimics malignant ovarian cancer and epithelial carcinoma must be ruled out first 3, 4, 5, 8, 6. The bilateral nature of the masses and advanced presentation strongly favor epithelial malignancy over benign stromal tumors.
Next Steps in Management
According to current guidelines, this patient requires:
- CT imaging of thorax, abdomen, and pelvis to complete staging 1
- Surgical exploration with comprehensive staging and intraoperative frozen section 7
- Pathological examination of adequate tumor tissue for definitive diagnosis and molecular testing 1
- If mucinous histology is suspected, measure CEA and CA 19-9 to distinguish primary ovarian from gastrointestinal metastasis 1, 2