## Distinguishing Epithelial Ovarian Cancer from Granulosa Cell Tumor ### Key Discriminating Feature **High-Yield:** Bilateral involvement at presentation is the most reliable clinical discriminator. Epithelial ovarian cancer (EOC) presents with bilateral disease in 40–50% of cases, whereas granulosa cell tumors (GCT) are almost always unilateral (>95% of cases are stage I at diagnosis). ### Comparative Table | Feature | Epithelial Ovarian Cancer | Granulosa Cell Tumor | |---------|---------------------------|----------------------| | **Bilaterality at presentation** | 40–50% | <5% (nearly always unilateral) | | **Age of onset** | 6th–7th decade (peak 55–65 years) | 5th–6th decade (peak 50–55 years) | | **Histology hallmark** | Serous, mucinous, endometrioid, clear cell patterns | Call-Exner bodies, grooved nuclei, theca cells | | **Hormone production** | Minimal; CA-125 elevation | Inhibin (markedly elevated), estrogen; FSH suppressed | | **Stage at diagnosis** | 70% stage III–IV | 90% stage I | | **Prognosis** | Poor (5-year OS ~45% overall) | Better (5-year OS ~90% for stage I) | ### Clinical Pearl **Key Point:** The unilateral presentation of GCT is so characteristic that finding bilateral ovarian masses in a postmenopausal woman with elevated CA-125 should immediately prompt consideration of epithelial malignancy rather than a sex cord–stromal tumor. Bilateral disease is a hallmark of advanced epithelial EOC and reflects its aggressive metastatic potential. ### Why Bilaterality Matters 1. **Epithelial EOC** spreads via transcoelomic dissemination and lymphatic/hematogenous routes → bilateral involvement common 2. **GCT** is a low-grade sex cord–stromal tumor with limited metastatic potential → remains localized to one ovary in the vast majority [cite:Robbins 10e Ch 22] [cite:Williams Gynecology 4e Ch 31]
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