Immature teratoma of the ovary is graded based on the amount of immature neural tissue present. What is the defining feature of Grade 3 immature teratoma?

Explanation

## Grading of Immature Teratoma **Key Point:** Immature teratoma is graded on a 3-tier system based on the volume of immature neural (embryonic) tissue. Grade 3 (highest grade, worst prognosis) is defined by the presence of immature neural tissue in **more than 3 low-power fields (LPF) per slide**. ### Immature Teratoma Grading System | Grade | Immature Neural Tissue | Prognosis | 5-Year Survival (with chemotherapy) | | --- | --- | --- | --- | | **Grade 1** | < 1 LPF per slide | Excellent | ~95% | | **Grade 2** | 1–3 LPF per slide | Good | ~85–90% | | **Grade 3** | > 3 LPF per slide | Poor | ~60–70% | **High-Yield:** The amount of immature neural tissue is the **single most important prognostic factor** in immature teratoma. Higher grade correlates with higher risk of recurrence and metastasis. **Clinical Pearl:** Grade 1 immature teratomas have an excellent prognosis and may not require chemotherapy if completely resected. Grade 2 and 3 tumors require adjuvant chemotherapy (BEP: bleomycin, etoposide, cisplatin). **Mnemonic:** **LPF-3 Rule** — **L**ow-**P**ower **F**ield; Grade 3 = > 3 LPF (more immature tissue = worse grade). ### Microscopic Features - **Immature neural tissue:** primitive neuroepithelium, neural tubes, rosettes, undifferentiated mesenchyme - **Mature elements:** hair, sweat glands, bone, cartilage (may coexist) - **Key distinction:** Presence of mature tissue does NOT reduce the grade if immature neural component is extensive