Juvenile Granulosa Cell Tumor of the Infantile Testis

Abstract
We report the ultrastructure and immunohistochemical profile of seven juvenile granulosa cell tumors of the infantile testis. The infants' ages ranged from 1 day to 11 months. All tumors had characteristics ultrastructure with a mixture of spindle smooth-muscle and theca cells and polygonal granulosa cells. Clusters of polygonal granulosa cells were invested by a continuous basal lamina and contained bundles of distinct cytoplasmic filaments with evenly distributed dense bodies resembling smooth muscle. These filaments were occasionally attached to well-developed, prominent desmosomes. Tumor cells had a conspicuous rough endoplasmic reticulum and Golgi complex and occasional neutral fat droplets. In all tumors, mitochondria had laminated cristae and only rarely were there cristae with a tubulovesicular pattern characteristic of steroid secreting cells. Tumor cells stained focally with low-molecular-weight cytokeratins (8,18, and 19), smooth-muscle-specific actin, desmin, and more noticeably with vimentin. These ultrastructural and immunohistochemical features of dual epithelial-mesenchymal differentiation and distinct muscle-like filaments with dense bodies are characteristic of the juvenile granulosa cell tumor of the infantile testis.