Ovary, yolk sac tumour, H&E stain

Yolk sac tumor (endodermal sinus tumor) is the second most common malignant germ cell neoplasm after dysgerminoma. It is a highly malignant neoplasm, with early metastasis and invasion of surrounding structures and hematogenous metastases (frequently to lungs and liver). They occur most frequently in the second and third decades, followed by the first and fourth decades.

Yolk sac tumours present with abdominal enlargement and pain, and pelvic mass. They are almost always unilateral and large (>10 cm) with necrosis and hemorrhage. The microscopic features can be difficult to interpret, because the tumour can have a variety of growth patterns, including microcystic, macrocystic, polyvesicular, hepatoid, glandular (alveolar or endodermal primitive) papillary, and myxomatous.

Immunohistochemistry: positive for keratins, AFP, Glypican3, HNF-l B and negative for EMA.

This slide shows H&E stain See Related Content for AFP, HNF-1B, Glypican3, and EMA stains.