During a pathology seminar, a resident reviews the classification and characteristics of ovarian germ cell tumors. Regarding dysgerminoma and other germ cell tumors of the ovary, all of the following statements are correct EXCEPT:

Explanation

## Ovarian Germ Cell Tumors — Classification & Characteristics ### Dysgerminoma **Key Point:** Dysgerminoma is the ovarian counterpart of testicular seminoma, arising from primordial germ cells. It accounts for ~30–40% of malignant ovarian germ cell tumors. | Feature | Dysgerminoma | |---------|---| | **Age** | Adolescents and young adults (10–30 years) | | **Radiosensitivity** | Highly radiosensitive | | **Chemosensitivity** | Highly chemosensitive (BEP regimen) | | **Tumor Markers** | Normal AFP; normal or ↑ β-hCG (if admixed choriocarcinoma) | | **5-year Survival** | >95% with modern therapy | **Clinical Pearl:** Dysgerminoma is associated with gonadal dysgenesis, Y chromosome abnormalities (45,X/46,XY mosaicism), and Swyer syndrome — these patients require prophylactic gonadectomy of the contralateral gonad. ### Immature Teratoma **Key Point:** Immature teratomas are graded (1–3) based on the amount and degree of differentiation of immature neuroepithelium (primitive neural tissue). Grade 3 (highest immature component) carries the worst prognosis without chemotherapy. **High-Yield:** Modern platinum-based chemotherapy has dramatically improved survival even for grade 3 immature teratomas, with 5-year survival rates now >90%. ### Mature Cystic Teratoma (Dermoid Cyst) **Key Point:** Mature cystic teratomas are benign, well-differentiated lesions containing hair, teeth, and sebaceous material. Malignant transformation occurs in only **0.5–2%** of cases, typically in postmenopausal or older women. **Warning:** ~~Malignant transformation is COMMON~~ — this is INCORRECT. Malignant transformation is RARE (0.5–2%), not common. When it occurs, squamous cell carcinoma is the most frequent histologic type, followed by adenocarcinoma and melanoma. ### Why Option 2 (Malignant Transformation) Is Incorrect **High-Yield:** While malignant transformation of mature cystic teratomas CAN occur (especially in postmenopausal women), it is RARE (0.5–2%), not common. The statement implies a high frequency, which is clinically misleading. Most mature cystic teratomas remain benign throughout life. ### Risk Factors for Dysgerminoma **Mnemonic:** **DYSGER** — Dysgenesis, Y chromosome abnormalities, Swyer syndrome, Gonadal dysgenesis, Elevated risk in XY mosaicism, Recurrent in contralateral gonad if not removed. **Clinical Pearl:** Patients with gonadal dysgenesis or Y chromosome mosaicism (45,X/46,XY) have a 30% lifetime risk of developing a germ cell tumor (usually dysgerminoma). Prophylactic gonadectomy of the streak gonad is recommended. [cite:Robbins 10e Ch 22] [cite:Park 26e Ch 8]