Chiari malformation type III is a rare congenital anomaly. It consists of the posterior fossa contents herniation through an occipital or high cervical encephalocele sac. Although it has traditionally been associated with a high mortality rate, the absence of certain poor prognostic factors and appropriate medical and surgical treatment allow these children to survive and have a remarkable initial functional improvement. Surgical goals are defect repair, preservation of viable brain tissue, adequate skin coverage and hydrocephalus management. Despite all of this, the tendency of these newborns is to maintain a significant disability and if they present poor prognostic criteria, they usually demise within a short period of time. We report the case of a newborn with Chiari malformation type III diagnosed during pregnancy. After characterizing the anomaly with a postnatal MRI, the encephalocele was excised and multi-layer closure was performed. The patient progressively developed hydrocephalus during the postoperative period and required ventriculoperitoneal shunt placement. After an initial uneventful course, our patient suffered several episodes of respiratory disturbances. The child became ventilator dependent and palliative care was established in agreement with the parents after ruling out shunt malfunction.

Congenital mesoblastic nephroma (CMN) is a rare tumor, yet it is the most frequently diagnosed renal neoplasm in the first 3 months of life. CMN reports with prenatal magnetic resonance imaging (MRI) are scarce. Our aims were to describe a case with fetal MR imaging along with other findings, and to review the literature concerned with prenatal MRI detection of CMN. Upon routine ultrasound (US) examination of a 36-week pregnant woman, a fetal abdominal mass was disclosed. Prenatal MRI revealed a large, well-circumscribed renal mass of solid and cystic components, not invading the adjacent tissues, but compressing normal renal parenchyma of the lower pole of the left kidney. Thus, a low malignant renal tumor was considered. After Cesarean delivery, imaging including US and computerized tomography (CT) scan was performed on the apparently healthy boy and verified the prenatal MRI finding. Accordingly, left nephrectomy was performed at the age of 12 days. The pathology confirmed CT results of the solid and cystic components of the mass, in addition to the necrotic and hemorrhagic constitution. Cellular CMN was diagnosed, and ETV6 gene rearrangement was demonstrated by FISH analysis. No recurrence was detected within the 40 months follow-up after the operation. Our report described a rare and seldomly detected renal tumor in utero with the aid of MRI and reviewed the few related reports in the literature in which MRI was performed prenatally. This report also highlights the need for prenatal MRI as a complementary tool to US in cases with suspected fetal renal mass and recommends its use for carefully managing the possible risks during the perinatal period.