Primary orbital yolk sac tumour in a 14-year-old girl.

Yolk sac tumour is a common malignant germ cell tumour, which usually occurs in the testes or ovaries of infants. It can occasionally arise from a number of extragonadal sites. Extragonadal germ cell tumours of the head and neck region account for 5% of all benign and malignant germ cell tumours. The orbit is an extremely unusual location for development of primary yolk sac tumour. The present report concerns the case of a yolk sac tumour in a 14-year-old girl, arising as a primary tumour of the orbit with invasion of periorbital and intracranial spaces.