If everything else is normal, nothing to worry about. Choroid plexus cysts can be markers for Trisomy 18 but over 90% of T18 fetuses will have a heart defect and other abnormal findings. If the cysts are an isolated finding, no worries. Very common finding. Saw a case on Monday and one on Tuesday. They have no effect on brain function. They are located in the lateral ventricles and not within brain tissue.
My son had the same thing at his 18 week scan. Did another scan at about 28 weeks and it was gone.
I'm going back for another ultrasound next week, the ultrasound tech said the baby was curled up too much to get good pictures of the heart. I'm having faith everything will be fine, I did see online how common they are. And if everything else checked out/checks out fine. .baby should be ok.
My friends baby had 2 cysts on the brain. 2 weeks later they were gone! Try not to freak out too much. Stress isn't any better for the baby ;) I'm sure yours will be fine! Are they sending you to a specialist to get it further looked at?