% of ovarian tumours of non epithelial origin in childhood is :
**Core Concept**
In pediatric gynecology, ovarian tumors can be broadly classified into epithelial and non-epithelial types. Non-epithelial ovarian tumors in children are primarily germ cell tumors, which arise from the cells that give rise to the egg.
**Why the Correct Answer is Right**
Germ cell tumors account for approximately 70% of ovarian tumors in children. These tumors can be further sub-classified into benign, malignant, and borderline types. The most common malignant germ cell tumor in children is the dysgerminoma, while the most common benign tumor is the teratoma. Germ cell tumors can be distinguished from epithelial tumors by their distinct histopathological features and clinical presentation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the majority of ovarian tumors in children are not of granulosa cell origin. Granulosa cell tumors are more commonly found in adults and are a type of sex cord-stromal tumor.
**Option B:** This option is incorrect because the majority of ovarian tumors in children are not of dysgerminoma origin. While dysgerminoma is a common malignant germ cell tumor in children, it does not account for 70% of all ovarian tumors in this age group.
**Option C:** This option is incorrect because the majority of ovarian tumors in children are not of sex cord-stromal origin. Sex cord-stromal tumors, including granulosa cell tumors, are more commonly found in adults.
**Option D:** This option is incorrect because the majority of ovarian tumors in children are not of metastatic origin. Metastatic tumors to the ovary are more commonly found in adults and are a result of spread from other primary sites.
**Clinical Pearl / High-Yield Fact**
In children, ovarian tumors are often diagnosed incidentally during imaging studies for unrelated conditions. A high index of suspicion is required to diagnose these tumors early, as they can have a significant impact on the patient's quality of life and long-term prognosis.
**Correct Answer: C. 70%**