Steroidogenesis in a virilizing ovarian tumour.

A metabolic study with tissue from a virilizing arrhenoblastoma, using as precursors [7-3H]pregnenolone, [7-3H]17alpha-hydroxypregnenolone,[4-14C]17alpha-hydroxyprogesterone and [4-14C]testosterone, revealed that in spite of a deficient activity of 3beta-hydroxysteroid dehydrogenase-5-isomerase the overall production of testosterone was compensated by an increased activity of a lyase converting [4-14C]17alpha-hydroxyprogesterone to testosterone (via androstenedione) and was comparable to the production obtained by normal ovarian tissue. The masculinizing effects of the tumour in vivo were most probably caused by accumulation of testosterone due to deficiencies in enzymes catabolizing testosterone to 17-ketosteroids and its aromatization to oestrogen. The unique property of the arrhenoblastoma to convert [4-14C]17alpha-hydroxyprogesterone to [4-14C]11-deoxycortisol (Reichstein's compound S) suggests an adrenal origin of the tumour which may explain its limited capacity to aromatize testosterone.