Introduction

Simple renal cysts are often incidental findings on Ultrasound and CT scans. They are generally asymptomatic, and rarely present with flank pain, hypertension, infection, hematuria or erythrocytosis. We present a case of 64 year old woman with a large right renal cyst associated with moderately controlled hypertension and managed on multiple medications. The cyst was treated by CT guided percutaneous aspiration and alcohol sclerosis, resulting in well controlled blood pressure on less medicine. Utilization of cyst aspiration in this manner may avoid unnecessary surgical interventions. We found only two cases in the literature [₃,₄] that show the same course when applied to treatment of hypertension. Our case is a third example.

Case Report

A 64 year old white female presented for evaluation of moderately controlled hypertension. At the time of presentation, the patient was managed on multiple antihypertensives, which included atacand 32 mg daily, spirololactone 50 mg daily, bisoprolol/HCTZ (Ziac) 10/6.25 mg daily, methyldopa 250 mg twice a day, doxazosin 2 mg daily and a catapres TTS 2 patch every week. Her blood pressure ranged between 152-158 mm Hg systolic and 84-90 mm Hg diastolic on these medications. She had a history of right renal cyst, which was an incidental finding on previous CT scan of her abdomen. Physical examination of the patient was normal. She had normal blood work including complete blood count, electrolytes, urinalysis, urinary catecholamines, VMA and metanephrines. MRA of the renal arteries was normal but confirmed the presence of a large right kidney cortical cyst measuring approximately 13 cm and causing anteromedial displacement of the right kidney (Fig 1).

Figure 1

Stimulated plasma renin came back high as 11.9 ng/ml/hr (Normal 1.31-3.95). The patient then went to CT scan guided aspiration of the right renal cyst. A total of 800 ccs of clear fluid was drained. Later, contrast was injected demonstrating no communication between the cyst and the collecting system. Finally, the cyst was sclerosed with 95% ethanol. The cyst reduced in size significantly (Fig 2).

Figure 2

A week after aspiration of the cyst, the blood pressure dropped to 120/62 mm Hg. Pathology of the cystic fluid showed no malignant cells. After the procedure, the patient has been followed every six months for past four years. She is currently only on a single antihypertensive medication Hyzaar 100/25 mg daily. Her blood pressure has been well controlled and is around 136/80 mm Hg. Her last ultrasound demonstrated resolution of the original cyst. Her recent stimulated plasma renin is 2.01 ng/ml/hr.

Discussion

The incidence of simple renal cysts increases with age. They are found in one third of patients, fifty years of age or older [₁]. As a cause, their association with hypertension is rare. Large cysts cause ischemia by compressing the adjacent renal tissue and /or renal arteries, thereby stimulating the renin-angiotensin- aldosterone system, resulting in hypertension [₂]. Surgical removal or percutaneous decompression of the cyst has shown to improve the blood pressure in these patients [₃,₄,₅,₆,₇,₈,₉,₁₀,₁₁,₁₂,₁₃,₁₄,₁₅,₁₆,₁₇]. Renal cysts can be managed by percutaneous aspiration with [₃,₄] or without [₁₂,₁₃,₁₄,₁₅,₁₆] injection of sclerosing agents, marsupilisation [₁₇] and laparoscopic/open surgery [₅,₆,₇,₈,₉,₁₀,₁₁].

Percutaneous aspiration of the renal cyst and injection of a sclerosing agent has been studied in the literature and has shown to deliver better results in terms of symptom control and recurrence of the cyst. Aspiration alone has the disadvantage of a high recurrence rate [₂₆,₂₇,₂₈,₂₉]. Sclerosing agents cause inflammation and fibrosis of the cyst wall, thereby shrinking and preventing recurrence of the cyst. Different sclerosing agents like alcohol [₃,₄,₁₈,₁₉,₂₀,₂₁,₂₂,₂₃,₂₄,₂₅,₂₆,₂₇,₂₈,₂₉], minocycline [₃₁], tetracycline [₃₂], vibramycin [₃] and polidocanol [₃₀] have been used, all with good success. In our case we choose CT guided aspiration and injection of alcohol since it is effective, minimally invasive, has fewer complications when compared to surgical methods and can be performed in an outpatient setting. It was also diagnostic and therapeutic, as the blood pressure dropped and remained easier to control after the cyst was aspirated, proving the causal relationship between renal cyst and hypertension. We chose 95% alcohol as the sclerosing agent as it is inexpensive and had shown good results with no complications in the long term [₁₈,₁₉,₂₀,₂₁,₂₂]. We have followed the patient for four years with blood pressure measurements, and serial ultrasounds to look for the residual cyst size. There are only two case reports in literature where renal cyst with associated hypertension was managed by percutaneous cyst aspiration and instillation of the sclerosing agent alcohol, both with good results [₃,₄]. Our case is a third case, which lends credence to the desirability of this procedure under appropriate circumstances.

Conclusions

In conclusion, percutaneous aspiration and alcohol sclerosis is an effective, safe and minimally invasive therapeutic option for renal cysts causing hypertension. If the blood pressure doesn't respond to aspiration of the cyst, then other causes of hypertension should be looked for.

We, therefore, suggest percutaneous cyst aspiration and sclerosis as the first line of treatment for renal cysts suspected as a cause for hypertension before proceeding to invasive surgical procedures.