Normal karyotype in cultured chorionic villus cells, but mosaicism in amniotic and fetal cells.

A case with a normal male karyotype in cultured chorionic villus cells, but 46,XY/45,X/46,X,i(Yq) mosaicism in amniotic and fetal tissue is reported. The fetus was a phenotypic male. Pathological examination revealed discrete features, which might indicate a syndrome, and histological examination showed large, bright cells in the tubules of the testes. Possible explanations for discordance between the karyotype of embryonic and extraembryonic tissue are discussed.