CRYPTORCHIDISM AS A CAUDAL DEVELOPMENTAL FIELD DEFECT - A NEW DESCRIPTION OF CRYPTORCHIDISM ASSOCIATED WITH MALFORMATIONS AND DYSPLASIAS OFTHE KIDNEYS, THE URETERS AND THE SPINE FROM T10 TO S5

Cryptorchidism is a feature of abnormalities in the hypothalamo-pituit ary-testicular axis, and almost all disorders of sexual differentiatio n in which a testis is present. We found cryptorchidism to be associat ed with malformations and dysplasias of the kidneys, the ureters and t he spine from T10 to S5. The description of this association is new. T he association was seen in 18% of cryptorchid boys younger than 3 year s of age in a department of paediatric surgery, in 34% of cryptorchid foetuses who died in the third trimester, in 65% of cryptorchid patien ts with imperforate anus, and in all individuals with tritonmelia, the male variant of sirenomelia. Sirenomelia/tritonmelia is an extreme de gree of abnormal differentiation of the caudal developmental field, al so called caudal dysplasia, the caudal regression syndrome and the cau dal regression malformation sequence. Caudal developmental field defec ts were also the predominant abnormalities in the other groups of pati ents. Thus, cryptorchidism may be a feature of abnormal differentiatio n of the caudal developmental field. Position and histology of the und escended testes of the patients included in the association were simil ar to in cryptorchidism in general. In the literature the association was reported in 5-10% of boys considered to suffer from cryptorchidism only. Furthermore, our observations are concordant with recent theori es about cryptorchidism. Consequently, we propose that cryptorchidism in general may be a caudal developmental field defect. Study of crypto rchid patients exhibiting malformations or dysplasias of the kidneys, the ureters or the spine from T10 to S5 is essential in order to isola te new genetic disorders and to spot environmental factors causing cry ptorchidism.