Anterior choroid plexus cysts: distinction from germinolysis by high-resolution sonography.

Background: The aim of the present paper was to develop criteria identifying anterior choroid plexus cysts (ACPC) and distinguish these from germinolytic pseudocysts.

Methods: Cerebral sonography was performed in 2200 neonates with mean gestational age 40 completed weeks (range 23-42 weeks) and mean birthweight of 3450 g (range 340-4610 g). In the last 300 neonates cystic formations in the caudothalamic groove were studied prospectively using a high-resolution ultrasound system with linear scanhead, and the previous results were re-evaluated.

Results: In 22 neonates choroid plexus cysts outside the typical location in the choroid plexus glomus could be attributed to the anterior part of the choroid plexus in the lateral ventricles (prospectively analyzed in 16 of 300 neonates: 5% prevalence on high-resolution sonography). ACPC were located medial and behind germinolytic pseudocysts and best realized during sweep of the scanhead through the caudothalamic groove. In contrast to germinolytic pseudocysts, they had a spherical form, no septation and a thick, partial double wall. Larger cysts seemed to bounce.

Conclusions: ACPC are not rare and are identified by their location, form, and movement.