The tumour marker for Granulosa cell tumour is:
**Core Concept**
Granulosa cell tumours are a type of sex cord-stromal tumour that arise from the granulosa cells of the ovary. These tumours are known to produce various substances, including hormones and tumour markers, which can be used for diagnosis and monitoring.
**Why the Correct Answer is Right**
The correct tumour marker for Granulosa cell tumour is inhibin. Inhibin is a protein complex that is produced by the granulosa cells and inhibits the production of follicle-stimulating hormone (FSH) by the pituitary gland. Elevated levels of inhibin have been found in patients with Granulosa cell tumours, making it a useful tumour marker for diagnosis and monitoring. Inhibin is particularly useful in distinguishing Granulosa cell tumours from other types of ovarian tumours, such as serous cystadenocarcinomas.
**Why Each Wrong Option is Incorrect**
**Option A:** CA-125 is a tumour marker that is commonly used for monitoring ovarian cancer, but it is not specific for Granulosa cell tumours. CA-125 can be elevated in various types of ovarian tumours, including serous cystadenocarcinomas.
**Option B:** Beta-hCG is a tumour marker that is commonly used for monitoring trophoblastic disease, but it is not specific for Granulosa cell tumours. Beta-hCG can be elevated in various types of tumours, including choriocarcinomas and germ cell tumours.
**Option C:** LDH is a non-specific tumour marker that can be elevated in various types of tumours, including Granulosa cell tumours. However, it is not specific for Granulosa cell tumours and can be elevated in other types of tumours as well.
**Clinical Pearl / High-Yield Fact**
It's worth noting that inhibin is a useful tumour marker for Granulosa cell tumours, particularly in distinguishing them from other types of ovarian tumours. A high index of suspicion and careful clinical evaluation are essential for diagnosing Granulosa cell tumours, which can be challenging to diagnose based on imaging studies alone.
**Correct Answer: C. Inhibin.**