Other Cystic Diseases



Cysts of the renal medulla are features of two grossly disparate disorders. Medullary cystic dis­ease (nephronophthisis) occurs either as a rare, autosomal recessive disease or as a feature of some cases of retinitis pigmentosa. Medullary sponge kidney is a more common, benign disorder that may be discovered incidentally on abdominal radiographs.

Medullary cystic disease regularly results in endstage renal failure during adolescence or early adulthood. Prolonged enuresis in childhood due to a urinary concentrating defect is one early indication of the renal disease. Anemia is another early manifestation of the disease. Neither ra­diography nor renal biopsy has a high rate of suc­cess in demonstrating the small medullary cysts.

Medullary sponge kidney is a benign disorder that often presents as a result of passage of a renalcalculus. Colicky renal pain, hematuria, or uri­nary tract infection may herald the disorder; each symptom is the result of renal stone formation. Nephrocalcinosis occurs in about half the patients and accounts for discovery of asymptomatic pa­tients on routine abdominal radiographs. The di­agnosis is made on IVP by the characteristic radial pattern of contrastfilled medullary cysts. Treat­ment for urinary tract infection and renal calculus formation is indicated. Renal failure does not occur as part of the basic disease.