[7 cases of congenital multicystic kidney with special reference to its embryogenesis].

We have experienced 7 cases of multicystic kidney. The latest two cases, etiologically of interest, are reported herein with special reference to its embryogenesis. Case 6: A 4-year-old girl was referred to our clinic for further evaluation of mild azotemia and nonvisualization of left kidney. Left kidney was strongly thought to be multicystic kidney from abdominal CT, whereas her contralateral kidney exhibited hydrocalycosis resembling infundibular stenosis with diminished calyceal numbers. Nephrectomy of her left kidney was performed and histological studies confirmed renal dysplasia (primitive duct, metaplastic cartilage, etc.). Case 7: A 7-year-old girl was referred to Hakodate Kyokai Hospital for the evaluation of azotemia and low stature. Her right kidney was not visualized on IVP and her left kidney exhibited hydronephrosis with diminished calyceal numbers. Her right kidney was diagnosed as multicystic kidney on CT-scan. Pyeloplasty of her left kidney was performed. Multicystic kidney is a rather rare congenital disease. Association of various anomalies in contralateral kidney has been emphasized as well as the notion that infundibulopelvic stenosis is a linked in the clinical spectrum extending from cystic dysplasia of the kidney to hydronephrosis. Our last two cases seem to be included in this category of obstruction theory. As shown by microdissection technique (Potter), however, severe ampullary inhibition early in fetal life is also an attractive hypothesis. Diminished calyceal number of contralateral kidneys seen in our recent two cases is compatible with possibility of ampullary damage. Recent experimental study also showed that renal dysplasia is not solely caused by simply mechanical obstruction to urinary drainage, even when the obstruction is imposed at an early stage of renal development.