<prompt> True about Yolk sac tumour :Also called endodermal sinus tumourAlways have elevated AFP levelSchiller Duval bodies seen and Highly malignant bothAll  <response>: Ans. is a, b and c i.e. Also called endodermal sinus tumour; Always have elevated AFP level ; Schiller Duval bodies seen; and Highly malignant Endodermal sinus tumour : Endodermal sinus yolk sac tumour is second most common malignant germ cell tumour of ovary affecting mostly children or young women. Age group 14 - 20 years. Tumour is highly malignant and is most rapidly growing tumour of whole body. . Histologically the pathognomic finding is Schiller - Duval bodiesdeg which is a single papilla lined by tumour cells with a central blood vessel. Due to high rate of growth, tumour usually presents with acute abdomen. Mostly unilateral - other ovary is involved with metastatic disease only when there are other metastasis in peritoneal cavity. Almost all cases are associated with raised AFP and Alpha 1 antitrypsin. It is the most deadly malignant ovarian germ cell tumor. Treatment : Chemotherapy. It has a high propensity for rapid growth, peritoneal spread and distant hematogenous dissemination to the lungs. Highly malignant 