RESUMEN
The endodermal sinus tumor [EST] or yolk sac tumor [YST] is a malignant germ cell neoplasm that usually arises in gonads, but on rare occasion occurs in extragonadal sites such as mediastinum, retoperitoneum and intra cranium. Orbit is an extremely rare location for this tumor. In this report a primary yolk sac tumor in the orbit of a 17 months old child is presented. Patient had a rapidly progressive proptosis and high level of serum alpha fetoprotein [12500 IU/ml]. After surgical biopsy and histopathological diagnosis, the patient treated with 4 courses of a 3 drugs chemotherapeutic regimen. A period of 6 months follow up did not reveal any sign of recurrence. Although yolk sac tumor is very rare in orbit, a rapid and correct histopathological diagnosis in conjuction with immunohistochemical and other paraclinical evaluation and at last, effective chemotherapeutic regimens can provide a good prognosis and even cure for the patient