Fetal Megacystis: A New Morphologic, Immunohistological and Embriogenetic Approach

Congenital anomalies of the kidney and urinary tract (CAKUT) include isolated kidney malformations and urinary tract malformations. They have also been reported in Prune-Belly syndrome (PBS) and associated genetic syndromes, mainly 13, 18 and 21 trisomy. The AA focuses on bladder and urethral malformations, evaluating the structural and histological differences between two different cases of megacystis. Both bladders were examined by routine prenatal ultrasound screening and immunohistochemistry, comparing the different expression of smooth muscular actin (SMA), S100 protein and WT1c in megacystis and bladders of normal control from fetuses of XXI gestational age. Considering the relationship between the enteric nervous system and urinary tract development, the AA evaluated S100 and WT1c expression both in bladder and bowel muscular layers. Both markers were not expressed in the bladder and bowel of PBS associated with anencephaly. In conclusion, megacystis could be considered only a macroscopic definition, concerning the size of the fetal bladder rather than the embryologic origin; it may be a single or multiple malformation; the possible association with the bowel and/or encephalic malformations will decide the outcome and prognosis in fetal megacystis.