Background: Yolk sac tumor (YST) is a rare neoplasm that affects children and adolescents.
Cases: Fine needle aspiration biopsies from seven patients with YSTs were reviewed. Eosinophilic hyaline cytoplasmic bodies and irregular deposits of basement membrane-like material were easily recognizable in aspiration smears. Some of the tumor cells contained cytoplasmic vacuoles. These features correlated well with histologic appearances.
Conclusion: These findings are significant in the fine needle aspiration biopsy diagnosis of YST. A preliminary cytologic diagnosis of this tumor is valuable as a guide in planning further diagnostic studies and therapy.