in E5 Fundamentals of Gyn you have said that Estrogen is not reqd for development of Female ext Genitalia
Meanwhile in next chapter in topic Abnormal sexual Development XX karyotype : one of the cause is def. Of Aromatase which converts Androgen to Estrogen
In aromatase deficiency the androgens would not be converted to estrogen. So the presence of testosterone/androstenedione in female (which would normally not be there) is what would lead to the development of male external genitalia…I think that’s what it means.