[Renal sarcoidosis with a pseudotumoral pyelic localization].

Background: Renal sarcoidosis exceptionally presents as a unilateral pyelic pseudotumor as in this case where it was associated with granulomatous nephropathy.
Case Report: A 33-year-old man had a two-year history of systemic sarcoidosis with no renal involvement. He developed renal failure related to interstitial granulomatous nephropathy associated with a pyelic localization leading to unilateral hydronephrosis. Urine drainage associated with corticosteroid therapy provided a favorable course.
Discussion: Renal involvement in sarcoidosis is usually the consequence of hypercalcemia and hypercalciuria related to ectopic secretion of calcitriol by the sarcoidosic granulomas, with urinary lithiasis and nephrocalcinosis leading to renal failure and also granluomatous interstitial nephropathy. Glomerulopathy or obstructive nephropathy are rarely reported. Intraluminal localizations such as the pyelic lesion in our case are exceptional but must be detected early since they respond to corticosteroid therapy.