Localized Cystic Disease of the Kidney: A Rare Cause of Hypertension in a Young Adult
A 16-year-old male presented with a right abdominal and groin pain. There was no gross hematuria, fever, or lower urinary tract symptoms. Palpation of his right flank area was normal. He had hypertension for 2 years and his blood pressure (BP) measured 190/100 mm Hg at presentation. He had been taking antihypertensive drugs including valsartan hydrochlorothiazide (160/12.5 mg capsule once daily). No other abnormalities were found in the patient's history and on physical examination. Family screening was performed and no abnormalities were found. There was no family history of renal failure or cerebrovascular accident. His chest radiography and electrocardiography findings, urinanalysis, blood urea nitrogen, and serum creatinine levels were within normal limits. Other laboratory tests including lipid profile and liver functions were with in the normal range. His body mass index (BMI) was also in normal range (BMI: 22.1).\nAn abdominal ultrasound showed multiple variable-sized cysts in the upper pole of the right kidney with normal left kidney and lower pole of the right kidney []. Renal arterial color Doppler ultrasonography was normal. Abdominal computed tomography confirmed the ultrasound findings that the upper pole of the right kidney was filled with multiple cysts of different sizes with enhancing normal renal tissue between the cysts. There were no cysts in the other intra-abdominal organs. A renin blood test showed that the plasma renin level was moderately elevated (46 pg/ml, normal limits: 11-33 pg/ml). Selective intrarenal catheterization was performed to obtain venous blood samples. His drug was withdrawn four days before the selective renal vein studies and he was given 10 mg furasemide orally in the afternoon prior to the study. The procedure was started after placing the patient in a supine position for at least two hours. A catheter was introduced through the femoral vein and it was advanced using fluoroscopic guidance. Blood samples for plasma renin level were drawn from both main renal veins and from the upper and lower segmental draining veins of each kidney. The highest renin level was measured in the right upper segmental vein (92 pg/ml). Renin levels of the right lower segmental vein and the left renal veins are shown on .\nIn order to further characterize the lesions, MRI was performed. A gadolinium-enhanced MRI revealed that the upper pole of the right kidney was completely filled with multiple round, well-marginated cysts of varying size without capsule formation []. There were no solid areas within the cysts and renal parenchyma between the cysts was normally enhancing. Technetium-99m-dimercaptosuccinic acid (Tc-99m DMSA) renal scintigraphy showed decreased renal uptake at the upper half of the right kidney. After discussion with the physicians and the parents, a decision was made to perform partial nephrectomy to eliminate the source of the apparent renin-dependant hpertension. The patient underwent right upper pole heminephrectomy with a histopathological result confirming LCDK. Nephrectomy specimen on macroscopic examination showed conglomerate cysts of various sizes in the kidney []. Microscopy examination showed cysts containing dark brown or clear serous fluid and surrounded by mono-layered flat-cuboidal epithelium without evidence of tumor or papillary formation [].\nAfter surgery the patient's blood pressure returned to normal levels without any need for antihypertensive medication. The patient is under follow-up on outpatient basis and has maintained good renal function during the last two years. Follow-up ultrasound examinations showed normally appearing residual right kidney and left kidney.