[Rare forms of female pseudohermaphroditism: when to investigate?].

The congenital adrenal hyperplasia is the commonest cause of ambiguity of the external genitalia at birth, due to classic forms of 21-hydroxylase and 11beta-hydroxylase deficiencies. 3beta-hydroxysteroid dehydrogenase (3betaHSD) is a rare disorder that affects both sexes and female patients may have ambiguous genitalia. Familial glucocorticoid resistance is characterized by increased cortisol secretion without clinical evidence of hypercortisolism, but with manifestations of androgen and mineralocorticoid excess, caused by glucocorticoid receptor gene mutation, and rarely can lead to female pseudohermaphroditism. Placental aromatase deficiency is a rare disease characterized by a masculinized female fetus and a virilized mother, which should be considered in the absence of fetal adrenal hyperplasia and maternal androgen-secreting tumours. Finally, mutations of P450 oxidoreductase causes disordered steroidogenesis with ambiguous genitalia. The investigation of abnormal sexual development requires an initial karyotype analysis and serum 17OH progesterone, 11 deoxycortisol, 17 pregnenolone, and androgen measurements to assess the diagnosis of different forms of congenital adrenal hyperplasia.