An unusual mosaic karyotype detected through prenatal diagnosis with duplication of 1q and 19p and associated teratoma development.

A 40-year-old white woman underwent amniocentesis for advanced maternal age at 15.4 weeks gestation. Fetal chromosome analysis demonstrated two distinct cell lines: 46,XX,t(1;19)(p11;p11)]--10%; and 47,XX,t(1;19)(p11;p11) + der(1)t(1;19)(p11;q11)]--90%. The latter karyotype was trisomic for both 1q and 19p. The mother carried the balanced translocation; the father had a normal karyotype. Amniotic fluid alpha-fetoprotein level was elevated and an acetylcholinesterase band was detected. Level II ultrasonography at 17 and 24 weeks revealed several abnormalities, including a large facial cleft and a probable facial teratoma and intracranial tumor. Autopsy following pregnancy termination confirmed the presence of both. Chromosome evaluation of 172 metaphases of both the epignathus and the intracranial teratoma demonstrated a predominance of the cell line with 47 chromosomes (166/172 = 96.5%), while from nonteratoma tissue (lung, liver, skin, and brain) only the balanced karyotype was detected. These observations suggest that the chromosomal imbalance is instrumental in the etiology of the teratoma.