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Mucinous cystadenocarcinoma is a malignant epithelial ovarian tumor characterized by multilocular cystic masses lined with mucin-secreting epithelium, demonstrating stromal invasion and architectural complexity.

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It represents the malignant end of the mucinous tumor spectrum (adenoma → borderline → carcinoma).

Etiopathology

• Cell of origin: Ovarian surface epithelium with mucinous differentiation.
• Epidemiology:
  • Occurs typically in 40–70 years (older than mucinous cystadenoma).
  • Accounts for ~10–15% of primary ovarian carcinomas.
  • Most mucinous tumors of ovary are benign (~75%), ~10% borderline, and only ~10–15% malignant.
• Laterality: Usually unilateral; bilateral disease is more often metastatic (especially from gastrointestinal primaries such as appendix, stomach, colon).
• Molecular associations: KRAS mutations are common.

Clinical Features

• Symptoms are often due to large size: abdominal distension, pain, pressure symptoms (urinary frequency, constipation).
• May present with ascites, weight loss, or pleural effusion (Meigs-like syndrome).
• If ruptured → may cause pseudomyxoma peritonei (though more often appendiceal in origin).

Gross Pathology

• Large, multiloculated cystic mass, often >20 cm.
• Contains thick, gelatinous, mucinous fluid.
• Papillary projections, mural nodules, and solid components are common (unlike benign form).
• Areas of hemorrhage and necrosis may be present.
• Surface involvement → peritoneal implants if advanced.