<s>[INST] context: Extragonadal germinal cell syndromes are rare tumors that predominantly affect young males. Literature suggests that the only known risk factor for extragonadal germ cell tumors (EGCTs) is Klinefelter syndrome (47XXY), which is associated with mediastinal nonseminomatous germ cell tumors. They are characterized by their location on the midline from the pineal gland to the coccyx. In extragonadal germ cell tumors, no evidence of a primary malignancy is present in either the testes or ovaries by radiologic imaging or physical examination. Extragonadal germ cell tumors produce a rich symptomatology and may reach large volumes if they arise in silent areas. Histologically, they mirror their gonadal counterpas with which they share the same chemosensitivity and radiosensitivity. Modern approaches to diagnosis and treatment can result in high rates of long-term survival and even cureA number of different types of germ cell tumours can develop in the mediastinum. These are much more common in males than females. They are generally put into 2 main groups Non seminoma germ cell tumours (in females these are called non dysgerminomas) - including teratomas, choriocarcinomas, embryonal carcinomas and yolk sac tumours Seminomas (in females these are called dysgerminomas) Some teratomas can be non cancerous (benign).Many people with a tumour in the mediastinum don't have any symptoms. The doctor might spot the tumour on a chest X-ray you had for another reason. If symptoms are present they might include Shoness of breath Pain in the chest A cough Raised temperature Weight loss Night sweats [/INST] question: The commonest site for extragonadal germ cell tumour is- | options: A: Retroperitoneum B: Sacrococcygeal region C: Pineal gland D: Mediastinum | answer: D </s>