Among malignant ovarian germ cell tumors, which is the most common type encountered in clinical practice?

Explanation

## Most Common Malignant Ovarian Germ Cell Tumor **Key Point:** Dysgerminoma is the most common malignant ovarian germ cell tumor, accounting for 30–40% of all malignant ovarian germ cell neoplasms. ### Epidemiology - **Age of presentation:** Adolescents and young women (10–30 years, peak 20–25 years) - **Association:** Increased risk in gonadal dysgenesis (Turner syndrome, XY gonadal dysgenesis), cryptorchidism, and infertility - **Bilaterality:** ~10–15% of cases (higher than other germ cell tumors) ### Pathology & Histology - **Appearance:** Homogeneous, solid, tan-white mass with possible hemorrhage and necrosis - **Microscopy:** Sheets of uniform cells resembling primordial germ cells, separated by fibrous septa with lymphocytic infiltration - **Immunohistochemistry:** Positive for OCT4, NANOG, CD117, and placental alkaline phosphatase (PLAP); negative for AFP and hCG (unlike other germ cell tumors) ### Clinical Features - **Presentation:** Abdominal mass, pain, or distension; may present with acute abdomen if rupture or torsion occurs - **Tumor markers:** Elevated LDH (non-specific); normal AFP and hCG (helps distinguish from yolk sac tumor or choriocarcinoma) ### Management & Prognosis - **Treatment:** Surgical resection (unilateral oophorectomy if fertility preservation desired) followed by chemotherapy (BEP: bleomycin, etoposide, cisplatin) - **Prognosis:** Excellent with modern chemotherapy; 5-year survival >95% for early-stage disease - **Chemotherapy sensitivity:** Highly chemosensitive, even in advanced stages ### Comparison with Other Malignant Germ Cell Tumors | Feature | Dysgerminoma | Yolk Sac Tumor | Immature Teratoma | Embryonal Carcinoma | |---------|--------------|----------------|-------------------|---------------------| | **Age** | 15–30 years | <5 years | <20 years | Rare in ovary | | **Marker** | PLAP, LDH | AFP (very high) | None specific | hCG, AFP | | **Histology** | Uniform cells, fibrous septa | Microcystic, endodermal | Immature tissues | Cuboidal cells | | **Bilaterality** | 10–15% | <5% | <5% | Rare | | **Frequency** | Most common malignant | Second most common | Third most common | Rare | **High-Yield:** Dysgerminoma is the ovarian counterpart of seminoma in the testis. Both are highly chemosensitive and have excellent prognosis with modern treatment. **Mnemonic:** **PLAP** = Placental Alkaline Phosphatase (marker of dysgerminoma and other germ cell tumors); **LDH** = Lactate Dehydrogenase (elevated in dysgerminoma but non-specific). **Clinical Pearl:** The combination of a young woman with an ovarian mass and elevated LDH (but normal AFP/hCG) should raise suspicion for dysgerminoma. Bilateral involvement in ~10–15% of cases mandates careful examination of the contralateral ovary.