Interstitial-cell tumor of the testis. Tissue culture and ultrastructural studies.

A case of a functioning interstitial-cell tumor in a 12-year-old Negro boy is reported. The patient manifested precocious puberty, with signs of sexually aggressive behavior. The ultra-structural studies of the tumor showed features similar to those of the few cases previously reported in the literature. One characteristic finding was the presence of numerous membranous whorls within the cytoplasm. The cells grown in tissue culture were maintained for at least 9 weeks and were confirmed as testicular interstitial cells. Ultrastructurally they were similar to the cells in vivo, as evidenced by the finding of cytoplasmic organelles related to steroid synthesis.