Neurocutaneous Melanosis Associated with Prenatally Diagnosed Arachnoid Cyst

Malformations of the central nervous system (CNS) are among the most common congenital anomalies. The development of ­diagnostic­ultrasound­imaging­has­resulted­in­significant­advances in fetal neurosonography in particular. Depending on the imaging technology, the time at which examination is performed,­and­the­experience­of­the­examiner,­a­very­precise­differential diagnostic assessment of fetal brain structures can be performed and the large majority of CNS anomalies can be correctly diagnosed [1]. In some cases and also in regard to the interdisciplinary counseling of pregnant women together with neuropediatrics, intrauterine magnetic resonance imaging (MRI) can serve as a supplementary method to diagnostic ultrasound imaging. Additional CNS anomalies can be detected on MRI in select cases [2–4]. Arachnoid cysts are known CNS anomalies that can be accurately evaluated on ultrasound and generally have a good prognosis when their occurrence is isolated [5].