Infertility in an XX male.

A case of an infertile male subject with 46XX female karyotype is reported. A testicular biopsy revealed hyalinized tubules with Sertoli cells and marked interstitial cell hyperplasia. Chromosomal studies showed the presence of 46 chromosomes with an XX sex chromosome constitution, confirmed with trypsin banding. XX male subjects present an interesting diagnostic problem and need to be differentiated from XXY male subjects with Klinefelter's syndrome. The clinical features of this rare syndrome are discussed and the literature is reviewed.