Localized cystic disease of the kidney.

OBJECTIVE: Localized cystic disease of the kidney is a benign nonsurgical condition. Its imaging and clinical features are characterized and differentiated from autosomal dominant polycystic kidney disease, multilocular cystic nephroma, and cystic neoplasm.
MATERIALS AND METHODS: Localized cystic disease was diagnosed in 18 patients on the basis of a review of imaging studies, clinical histories, and pathologic proof in four of the 18 patients. Average age at diagnosis was 54 years (age range, 24-83 years). Fifteen of the patients (83%) were men. CT was performed on 18 patients, sonography on nine, excretory urography on six, arteriography on four, and MR imaging on two.
RESULTS: Localized cystic disease was unilateral in all patients and characterized by multiple cysts of various sizes separated by normal (or atrophic) renal tissue in a conglomerate mass suggestive of cystic neoplasm. In some patients, involvement of the entire kidney, which was suggestive of unilateral autosomal dominant polycystic kidney disease, was seen. No cysts were seen in the contralateral kidney in 14 patients, and only one or two scattered small cysts were present in four patients. Clinical presentations included hematuria, flank pain, palpable abdominal mass, and localized cystic disease as an incidental finding. None of the patients had a family history of autosomal dominant polycystic kidney disease. Ten patients underwent follow-up (follow-up range, 1-12 years); nine patients underwent imaging follow-up and one patient underwent clinical follow-up, which showed stability of disease. Four patients underwent nephrectomy for suspected renal neoplasm.
CONCLUSION: Familiarity with localized cystic disease of the kidney and its imaging findings is important to avoid unnecessary surgery and to differentiate the disease from autosomal dominant polycystic kidney disease.