[Mediastinal tumor as a cause of fetal hydrops]

Unusual case of fetal hydrops was presented. In a stillborn infant an Rh incompatibility was suspected as a cause of hydrops, although prentally an immunologic source of the illness was excluded. Post-mortem a large polycystic mediastinal teratoma with cardiac and pulmonary hypoplasia was stated as a main cause of the hydrops. Additionally, histopathological examination proved this diagnosis. The mediastinal tissue contained immature epithelial, mesenchymal and blastemal elements. The congenital teratomas should be taken for account in problematic diagnosis of complicated cases.