Case report

The following images show a case of a fetal interhemispheric arachnoid cyst observed at 28 weeks. It was a first pregnancy of a nonconsanguineous couple. The fetus was scanned at 13 weeks and the findings were normal. The triple test was also negative.

At 28 weeks the interhemispheric arachnoid cyst of the fetus was discovered. The lateral cerebral ventricles and corpus callosum were of normal size and morphology. Serological tests (Toxoplasmosis, Rubeola, Parvovirus B19, HIV, CMV, Herpes and Chikungunya) were negative, and so was the Kleihauer test. Amniocentesis was not performed.

MRI confirmed the sonographic findings. The neonate was delivered at term (3200g, boy). Postnatal ultrasonography confirmed the findings, but neurological examination of the neonate was normal. His laboratory tests showed a normal coagulation and no signs of an infection.

Images 1, 2: The images show a cystic structure of the fetal brain representing the interhemispheric arachnoid cyst. On the image 2 the cyst appears to be bilocular.

Images 3, 4: The images show the interhemispheric arachnoid cyst.

Images 5, 6: The images show sagittal scans of the fetal brain with normal anatomy of the corpus callosum. The interhemispheric cyst is localized dorsally to the corpus callosum.

Images 7, 8, 9, 10, 11, 12, 13, 14: MRI images showing the interhemispheric cyst of the fetal brain.