CYSTIC NEPHROMA: AN UNUSUAL RENAL LESION

Abstract

Cystic nephroma, invariably confused with renal cell carcinoma, is rare. It has been described in the literature under various names. Recognition of this entity has a prognostic and diagnostic significance. CASE REPORT A 57-year-old man presented with a painful right renal mass and hematuria. He was mildly anemic. Kidney function tests, and films of the kidneys, ureters and bladder were normal. Excretory urography showed increased renal size, delayed excretion and splaying of pelvicaliceal system on the right side, which were confirmed on ultrasonography and computerized tomography. Urinary cytology was normal. Right nephroureterectomy was performed. The kidney was 14 3 10.5 cm. and had a 4.5 3 3.5 cm. nodule near the upper pole. On cut section this nodule was comprised of well differentiated areas of cysts filled with clear fluid, and not communicating with each other or the collecting system. There was no hemorrhage, necrosis or calcification. Microscopically, the cyst walls were comprised of cuboidal or flattened epithelium, and the supporting stroma demonstrated fibroblastic activity (see figure). DISCUSSION Multilocular cystic nephroma is rare.1 It may occur in neonates to patients 70 to 80 years old. Differential diagnoses ranging from polycystic kidney, hydronephrotic kidney, nephroblastomas and renal cell carcinoma have been made in patients with cystic nephroma. Cases with a suspicion of malignancy have been subjected to preoperative radiotherapy and chemotherapy. Multilocularity, absence of communication between the cyst and kidney tissue, presence of locules with no communication between them, locules filled with clear fluid, normal residual kidney and absence of fully developed nephrons or part of the nephron in the septa of locules, short clinical history, mass with history of pain and presence or absence of hematuria are all symptoms of multilocular cystic nephroma.2 Many consider the condition to be a developmental abnormality, that is cystic disease. Others consider it to be nephroblastoma with benign differentiation in children. 3 However, prompt diagnosis and treatment are required. Nephrectomy is the adequate treatment with no need for chemotherapy and radiotherapy. The condition should be thoroughly differentiated from nephroblastoma in children and cystic renal carcinoma in adults. There have been no reports of metastasis or recurrences in these cases.