Prenatal diagnosis of frontonasal dysplasia with anterior encephalocele.

Frontonasal dysplasia is a rare congenital anomaly affecting the eyes, nose and forehead, and occurs sporadically in most of the cases. A 24-year-old woman was referred to our unit at 27 weeks gestation due to the preliminary diagnosis of encephalocele. The sagittal and axial sonography of the fetal face depicted a midline mass measuring 3.8 × 4.2 cm, projecting anteriorly between the fetal orbits and extending from the the upper aspects of the forehead to the nasal bridge, which was consistent with the frontal (anterior) encephalocele. There were prominent hypertelorism and two facial clefts, and the nostrils were extremely separated. Following genetic counseling, the couple requested termination of pregnancy. Fetal pathologic examination confirmed the diagnosis of frontonasal dysplasia and anterior encephalocele with no additional major malformation. The fetal karyotype was normal and no mutation in the ALX1 gene was found, excluding ALX1-related frontonasal dysplasia in the differential diagnosis. Fetuses with neural tube defect may suffer from associated syndromes and disorders, as with our case. The presence of frontonasal dyplasia should be considered when an anterior encephalocele is detected by ultrasonography.