Résumé
Parapelvic renal cyst, also designated as pericalyceal lymphangiectasis, is an unusual lesion that is usually brought to light during surgery for ureteropelvic junction obstruction or recurrent pyelonephritis. Grossly, the renal pelvis is enveloped by a multilocular cystic mass filled with clear fluid. This lesion is confined to the peripelvic tissues and does not extend into the parenchyma, which, however, may show the effects of hydronephrosis or pyelonephritis. A 50-year-old man presented with hydronephrosis. An ultrasonography revealed hydronephro-sis of the left kidney. Intravenous pyelography and DMSA ("Tc-Dimercaptosuccinic acid) scan showed nonfunctioning kidney of the same side. Simple left nephrectomy was done. The renal pelvis was mildly dilated and a cyst was found buldging into the renal pelvis. The content was watery clear and the cyst was not connected to the renal pelvis or calyces. The cyst was round unilocular and lined by attenuated single layer of endothelial cells. The endothelial cells showed no reactivity to factor-VIII related antigen. With these findings, we concluded that this cystic lesion is basically lymphatic cyst and hydronephrosis was caused by the compression of pelvic out-flow of the kidney.