[Cellular characteristics of yolk sac tumor]

Morphological analysis of imprint cytology and histology was performed in 5 patients with yolk sac tumor (YST). The age of the patients ranged from 14 to 37. The level of AFP ranged from 460 ng/ml to 13,464 ng/ml. Five patients had a primary lesion in the ovary. These five cases of YST were histologically evaluated and classified into 4 patterns. As a result, the endodermal sinus pattern was the most frequently identified, followed by the polyvesicular vitelline pattern. As with imprint cytology findings in 4 YST cases, cuboidal cells were the most frequently observed; cuboidal cells and nuclei were both cuboidal in shape and 25-40 mu and 20-25 mu in diameter respectively. The chromatin had fine to coarse granular patterns. The nuclear.cytoplasmic (N/C) ratio was 50-70%, and each nucleus contained one to four nucleoli. Next to cuboidal cells, spindle-shaped cells were most frequently noticed; 20-40 mu in size with spindle-shaped nuclei 10-20 mu in diameter and had a fine to coarse granular chromatin pattern. The nuclei of the 30-50% N/C ratio cells contained one to two nucleoli. Naked cells and bizarred cells were also noticed.