Prenatal diagnosis of atypical cystic lesions of the fetal scalp.

Two cases of cystic lesions of the fetal scalp are described. They were initially thought to be meningoceles, but the brain was normal on ultrasound examination and there were no associated abnormalities. In the first case, by 26 weeks' gestation, the original cystic lesion had regressed to a dense tissue mass; in the second case, the cyst remained as a small anechoic mass. Postnatal assessment in the first case revealed a plexiform skin lesion measuring 40 x 15 mm on the left parietal bone. This was mobile and not attached to the underlying structures. The skull showed no obvious defect and a cranial scan was normal. In the second case, an epidermal cyst was diagnosed.