2006-09-06-10 Idiopathic subependymal pseudocyst © Cuillier www.thefetus.net/
Idiopathic subependymal pseudocyst
Cuillier F, MD *
* Department of Obstetrics and Gynecology, Hôpital Félix Guyon, rue des Topazes, 97400 Saint-Denis, Reunion Island, France
This is a 24-year-old woman, G3P2, with two normal scans at 13 weeks and 24 weeks. The first trimester screening was normal. At 32 weeks, a scan revealed a cyst on the anterior horn of the two ventricles of the fetal brain. The lateral ventricles were not dilated. The posterior fossa and the corpus callosus were normal.
Magnetic resonance imaging (MRI) was performed. The frontal horns of the lateral ventricles appeared dilated on T2-weighted sequences. Cysts were found laterally close to the ventricle on axial and parasagittal planes, far from the germinal zone and from the superior and external margin of the lateral ventricle. The signal was compatible with fluid-filled cystic masses. The rest of the fetal brain was normal. T1-weighted sequences showed adequate myelinization. MRI excluded an hemorrhagic process.
Serological tests were performed including HBV, HBC, Herpes, EBV, Parvovirus B19, Rubella, Toxoplasma, HIV and CMV. All these results were negative. The karyotype was also normal. Predisposing risk factors for periventricular leukomalacia (such as non-steroidal anti-inflammatory drugs, cocaine abuse, abdominal trauma, vaginal bleeding and pre-eclampsia) were excluded. Periventricular hemorrhage associated with fetal alloimmune thrombocytopenia was also excluded by negative maternal anti-platelet antibodies.
The hypothesis of single subependymal pseudocysts was suggested. The couple decided to continue the pregnancy.
Vaginally delivery occurred at 38 weeks. A healthy boy was born with normal Apgar scores and normal weight (3500g). Neonatal neurological examination was strictly normal at birth and one month latter. Laboratory data showed a normal coagulation screening and there were no clinical or serological signs of congenital infections. At day three, a transfontanellar scan showed ventricles with little broadening of the frontal horn. The temporal horn was normal.
The diagnosis seemed to be confirmed as a subependymal pseudocysts or congenital periventricular pseudocysts or subependymal germinolytic cysts.
Scan at 32 weeks showing the subependymal cyst
MRI at the level of the lateral ventricles. A cystic lesion is located bellow the right and the left frontal horn of the lateral ventricles