Pediatric hydronephrotic segmental renal dysplasia with ipsilateral ureterovesical obstruction--rare coincidence or a consequence?

Obstruction in the developing urinary tract during embryonic life is one of the factors promoting disordered metanephric development in renal dysplasia. Dysplastic kidneys usually undergo involution during the first 5 years of life. Herein, we narrate a rare case of hydronephrotic segmental dysplasia co-existing with ipsilateral ureterovesical obstruction, in a 7-year-old male child, masquerading as hydronephrosis. Etiopathogenesis of segmental dysplasia presenting at this age is not clearly understood, and could be a consequence of intrauterine obstructive uropathy. Histologic evidence of dysplasia in a hydronephrotic kidney should warrant a close follow-up for pathologic changes in the contralateral kidney or urinary tract.