What is the most likely diagnosis and optimal initial management for a 52‑year‑old postmenopausal woman with progressive abdominal distention, massive ascites, a 7–8 cm irregular solid right adnexal mass, omental caking, peritoneal and hepatic surface implants, bilateral hydronephrosis, cytology showing malignant glandular cells consistent with adenocarcinoma, markedly elevated cancer antigen 125, anemia, thrombocytosis, hyponatremia, hypokalemia, and hypoalbuminemia?

Advanced Ovarian Cancer with Peritoneal Carcinomatosis

This patient has advanced-stage (FIGO Stage IV) high-grade serous ovarian carcinoma requiring immediate referral to a gynecologic oncologist for primary cytoreductive surgery followed by platinum-based chemotherapy. 1, 2

Most Likely Diagnosis

High-grade serous ovarian carcinoma is the diagnosis, accounting for approximately 70% of epithelial ovarian cancers and presenting with this exact clinical picture. 3 The constellation of findings is pathognomonic:

• Postmenopausal status with progressive abdominal distention and massive ascites 1
• Irregular solid adnexal mass (7–8 cm) with malignant IOTA descriptors 1
• Omental caking and peritoneal implants indicating widespread peritoneal carcinomatosis 1
• Hepatic surface nodules confirming Stage IV disease 1
• Markedly elevated CA-125 (585 U/mL) — levels >65 U/mL in postmenopausal women with complex masses have 100% specificity for malignancy 1
• Cytology showing adenocarcinoma with glandular features consistent with Müllerian origin 1
• Bilateral hydronephrosis from tumor compression 1

The operative findings of massive tumor implants throughout the peritoneum with non-identifiable ovaries further confirm advanced disease. 1

Optimal Initial Management Algorithm

Step 1: Immediate Gynecologic Oncology Referral

All patients with suspected advanced ovarian cancer must be referred immediately to a gynecologic oncologist without delay. 1, 2 Surgery performed by a specialist significantly impacts survival outcomes. 1

Step 2: Complete Staging Workup (Within 1 Week)

Before definitive surgery, complete the following:

• CT chest with contrast to evaluate for pleural effusion (Stage IV confirmation) and supraclavicular lymphadenopathy 1
• Baseline laboratory panel including complete blood count, comprehensive metabolic panel, liver function tests, and coagulation studies 1
• Preoperative CA-125 level (already obtained at 585 U/mL) serves as baseline for monitoring treatment response 1
• Consider CEA and CA 19-9 only if mucinous histology suspected (not indicated here given serous features) 3, 2

Do NOT delay surgery for additional imaging such as MRI or PET-CT, as surgical exploration provides definitive staging. 1 CT scanning is not a useful preoperative staging tool beyond identifying Stage IV disease. 1

Step 3: Primary Cytoreductive Surgery

The standard initial treatment is maximal cytoreductive surgery (debulking) performed by a gynecologic oncologist. 1 The goal is complete macroscopic resection of all visible disease. 1

Surgical staging and debulking must include: 1

• Total abdominal hysterectomy and bilateral salpingo-oophorectomy
• Omentectomy (omental caking already documented)
• Peritoneal biopsies and resection of all visible implants
• Pelvic and para-aortic lymph node assessment
• Appendectomy (if mucinous features present)
• Resection of bowel or other organs if necessary to achieve complete cytoreduction

Critical surgical principle: Peritoneal biopsies alone are insufficient — adequate tissue from the ovarian tumor itself must be obtained for definitive histologic diagnosis and molecular testing. 1

Step 4: Adjuvant Platinum-Based Chemotherapy

Following surgery, platinum-based combination chemotherapy is standard treatment. 1 The typical regimen is carboplatin plus paclitaxel for 6 cycles. 1

CA-125 monitoring during chemotherapy: 1

• Measure before each chemotherapy cycle
• Measure one month after completing the final cycle
• Declining CA-125 indicates treatment response 1

Critical Management Considerations

Addressing Immediate Complications

Before definitive surgery, manage: 1

• Bilateral hydronephrosis: Urology consultation for possible ureteral stent placement to preserve renal function 1
• Massive ascites: Therapeutic paracentesis for symptomatic relief if respiratory compromise present 1
• Anemia (Hgb 9.9): Transfusion if symptomatic or Hgb <8 g/dL perioperatively 1
• Hypoalbuminemia and electrolyte abnormalities: Nutritional optimization and correction before surgery 1

Neoadjuvant Chemotherapy Consideration

Neoadjuvant chemotherapy followed by interval debulking surgery is an alternative approach if: 1

• Performance status is too poor for immediate surgery
• Disease is deemed unresectable at initial exploration
• Significant medical comorbidities preclude safe cytoreduction

However, this patient underwent exploratory surgery revealing Stage IV disease, so the decision point is whether complete cytoreduction was achievable. 1 If optimal debulking (residual disease <1 cm) was not achieved, neoadjuvant chemotherapy followed by interval debulking is appropriate. 1

Tissue Requirements for Molecular Testing

Ensure adequate tissue is obtained for histologic subtyping and molecular characterization, as this guides targeted therapy decisions (BRCA testing, homologous recombination deficiency testing for PARP inhibitor eligibility). 1, 3

Common Pitfalls to Avoid

Do not delay referral for additional imaging studies — CT chest/abdomen/pelvis with contrast is sufficient for surgical planning in obvious advanced disease. 1, 2

Do not rely on CA-125 normalization alone to assess treatment response — combine with radiologic and clinical assessment. 3

Do not perform fine-needle aspiration of the adnexal mass, as capsule rupture worsens prognosis. 2

Do not dismiss the diagnosis based on normal CA-125 in other patients — while this patient has markedly elevated CA-125, remember that 50% of early-stage ovarian cancers have normal levels. 3, 2

Prognosis and Follow-Up

Stage IV ovarian cancer has a 5-year survival rate significantly lower than early-stage disease, but maximal cytoreductive surgery combined with platinum-based chemotherapy offers the best chance for prolonged survival and quality of life. 1 Complete cytoreduction to no visible residual disease is the single most important prognostic factor. 1

Post-treatment surveillance includes: 1, 3

• CA-125 measurement at each follow-up visit
• Physical examination every 2–3 months initially
• CT imaging as clinically indicated for suspected recurrence
• Rising CA-125 typically precedes clinical relapse by 2–6 months 3