Cytodiagnosis of yolk sac tumor.

To analyze cytomorphologic features of yolk sac tumors of childhood. Four cases of pediatric yolk sac tumor (YST), diagnosed by fine needle aspiration cytology were reviewed (1998-2002). Age of patients ranged from 1(1/2) to 5 years. Three cases presented clinically with an intra-abdominal mass while one case presented with a testicular mass. Fine needle aspirates had been obtained directly as well as under radiologic (USG/CT) guidance. Smears were stained with H & E and Papanicolaou stain. In all cases values of serum alpha-fetoprotein and hCG were available preoperatively. Histopathologic diagnosis was correlated with cytologic findings in all the cases. Cytologic examination showed richly cellular smears with a combination of morphological patterns. Characteristically, tumor cells were arranged in papillary groups, tight cell clusters and formed acinar structures. Cells showed enlarged, moderately pleomorphic, hyperchromatic nuclei and moderate amount of cytoplasm, some of which displayed cytoplasmic vacuolation, displacing the nuclei eccentrically. Preoperatively, serum alpha-fetoprotein level was raised in all cases. Histopathology confirmed the cytologic diagnosis. Yolk sac tumor is common among the germ cell tumors of pediatric age group which presents a spectrum of cytomorphologic features having important differences with other germ cell neoplasm, e.g. embryonal carcinoma. Clinicoradiologic features and tumor markers are additionally helpful for an accurate cytologic diagnosis.