·Encephalocele- The occiput is the most common site of the neural tube defect which presents an echogenic appearance if brain substance is within the sac. Demonstration of a defect in the cranium is necessary to make a diagnosis. Ninety percent occur in the midline. May be purely cystic. There may be associated hydrocephalus and microcephaly.
·Cystic hygroma- This is usually a neck mass and presents in the posterior nuchal region but the occiput may be affected. Sonography reveals a cystic mass with internal septations often associated with other anomalies.
·Normal fetal hair- Hair around the fetal, skull may occasionally be seen as bright scattered echoes which at times may mimic scalp edema or an encephalocele.
·Hemangioma- Hemangioma can present in the occipital region but is usually more anterior in location. The sonographic appearance is one of homogeneous echogenic areas within a cystic mass. Doppler may be helpful.
·Scalp edema- This is usually a part of a generalized anasarca related to the many causes of hydrops fetalis.
·Teratoma- When this lesion presents in relation to the cranium it occupies a more anterior extracranial location, and sonographically is seen as an irregular mass with cystic and solid areas usually arising from the sphenoid and extending outward through the nasal and oral cavities. AFP is usually elevated.