RESUMO
INTRODUCTION: The horseshoe kidney is a malformation of the upper urinary tract where the kidney is U-shaped. This condition results the fusion of the lower poles of the right and left kidneys on the midline. CASE PRESENTATION: We report a case of pyelonephritis revealing a rare form of horseshoe kidney with fusion of the lower pole of the right kidney with the upper pole of the left kidney, initially treated with urine drainage. DISCUSSION: Multiple etiological conditions may contribute to the development of a horseshoe kidney, in particular: the genetic/chromosomal predisposition, intrauterine environment and structural factors affecting kidney development and migration. CONCLUSION: Horseshoe kidneys reveal a veritable range of anatomical and embryological peculiarities, always suspect pyelonephritis on a horseshoe kidney in the presence of febrile abdominal pain in a patient with malformations.