Most common site of metastasis in choriocarcinoma
**Core Concept**
Choriocarcinoma is a type of gestational trophoblastic neoplasia (GTN) that arises from the placental tissue. It is known for its aggressive behavior and potential to metastasize to various organs. The most common site of metastasis in choriocarcinoma is a critical factor in determining the prognosis and treatment plan.
**Why the Correct Answer is Right**
The most common site of metastasis in choriocarcinoma is the lungs. This is due to the high vascularity of the lungs, which allows the tumor cells to easily disseminate and establish metastatic lesions. The lungs are also the first site of hematogenous spread, making them the most common site of metastasis in choriocarcinoma. The tumor cells express human chorionic gonadotropin (hCG), which is a marker of placental function, and this hormone is also elevated in choriocarcinoma. The hCG stimulates the growth of the tumor cells, promoting their metastasis to the lungs.
**Why Each Wrong Option is Incorrect**
* **Option A:** Liver - While the liver is a common site of metastasis for many cancers, it is not the most common site for choriocarcinoma.
* **Option B:** Brain - The brain is a rare site of metastasis for choriocarcinoma, and it is not the most common site.
* **Option D:** Bone - Bone metastasis is not a common feature of choriocarcinoma, and it is not the most common site of metastasis.
**Clinical Pearl / High-Yield Fact**
Choriocarcinoma is a highly vascular tumor that can metastasize to the lungs, and it is often associated with elevated levels of hCG. The hCG level can be used as a marker to monitor the response to treatment and detect recurrence.
**Correct Answer:** C. Lungs