A case of a Dandy-Walker variant: the importance of a multidisciplinary team approach using complementary techniques to obtain accurate diagnostic information.

Dandy-Walker malformation is a rare abnormality of the central nervous system (CNS) with a reported incidence of 1 in 25,00-35,00 live births and a slight female predominance. It accounts for 1-4% of cases of antenatally detected hydrocephalus. Dandy Walker variant forms part of the spectrum of Dandy Walker malformation. It is characterized by partial agenesis of the vermis, resulting in communication between the fourth ventricle and the cisterna magna. Dandy Walker malformation demonstrates an enlarged posterior fossa, with high insertion of the torcula herophili, as well as other features. In the diagnostic workup, ultrasound is reliable and accurate for making the diagnosis. In utero, fetal MRI can be used to confirm the diagnosis and also to identify any associated abnormalities. In cases of termination of pregnancy, autopsy will offer the diagnosis and provide additional information to assess the risk for future pregnancies and to help in counselling the parents. Autopsy is considered the gold standard for accurate diagnosis of the fetal abnormality. We report the unexpected finding of complete absence of the cerebellum due to maceration at autopsy, even though it was clearly demonstrated (but abnormal) on the antenatal ultrasound scan and MRI, as well as on post-mortem MRI. To the best of our knowledge, this has not been reported previously. Our case demonstrates the relevance of MRI when approaching a post-mortem examination with CNS malformation, and indicates that the "gold standard" might not always be autopsy.