ABSTRACT
In 1977 Scully first described the juvenile granulosa cell tumor of the ovary (JGCT) as a special variation of the granulosa cells tumor, which occurs in the two first decades of life, and 97% of the cases show characteristic microscopic and histological features. Five previous cases have been reported concerning the ultramicroscopic characteristics of this ovarian neoplasia. The purpose of this paper is to report the immunohistochemical and ultrastructural characteristics in a case of OJCGT which occurred in a four year old girl with isosexual precocious pseudopuberty. The presence of vimentin and absence of keratin was proven immunohistochemically in this ovarian neoplasia. Intermediate filaments were found ultrastructurally. The combined use of immunohistochemical and ultrastructural techniques has proven to be of extraordinary usefulness for the differential diagnosis between epithelial and non epithelial ovarian tumors and adds a new and highly specific method to characterize and differentiate the cells of embryonic carcinoma, choriocarcinomas and endodermal sinus tumors which are keratin positive.