What's your diagnosis in this second-trimester fetus?
Choroid plexus cyst
There is a small cystic lesion involving the choroid plexus. This finding is usually incidental and only needs a careful study of the fetus to rule out other congenital anomalies that, if present, may be associated with fetal aneuploidy. If this is an isolated finding, it should be followed up into the third trimester when it usually resolves spontaneously.