[Hypernephroma at the isthmus of a horseshoe kidney].

Presentation of a case of neoplasia associated to horseshoe kidney (HK). There is a tendency to suffer neoplasia in HK, hypernephroma being the most commonly seen, followed by renal pelvis tumours and Wilms' tumour with a frequency up to 8 times higher than in normal kidneys. This observation suggests that it should be compulsory to carry out cytogenetic studies in order to detect the 11p13 deletion as a possible marker in all children with HK.