[Cystic testis dysplasia with ipsilateral kidney agenesis].

A 6-year-old boy was seen for a left side scrotal mass which developed within a few months. Orchidectomy revealed an enlarged testis with multiple cysts in the head of epididymis and cystic transformation of the rete. At the same time, ipsilateral renal agenesis was found. This is a very rare combined malformation of the urogenital system which is of unknown etiology. Its pathogenesis may be related to developmental defects at the proximal and distal portion of the wolffian duct.