Male pseudohermaphroditism and gonadal mosaicism in a 47,XY,+22 fetus.

Trisomy 22 syndrome manifestations include cranial and facial anomalies. Ambiguous genitalia have been described in some fetus, but histological examination of the gonads has been rarely provided. We report here the first case of a male pseudohermaphrodite fetus with non-mosaic full trisomy 22 in amniocytes and presenting with ambiguous external genitalia, testes, and a uterus. In this case, we have further analyzed cytogenetically gonadal and uterine tissues. FISH analyses on paraffin-embedded gonads and uterus indicated the presence of two cell lines: XY and monosomy X, with 22%-50% of uterine cells having monosomy X, while 85%-100% of right and 77%-96% of left testicular cells were XY. The distribution of sex chromosomes observed in these tissues could explain the sexual differentiation observed in this fetus. On the other hand, this phenotype could also have resulted from cryptic anomalies in one or several genes implicated in sexual differentiation. Further evidence is thus needed before identifying the true cause of pseudohermaphroditism in our patient.