Simple Renal Cyst

Simple Renal Cyst

Article
Kidney & Bladder Health
Diseases & Conditions
+1
Contributed byMaulik P. Purohit MD MPHJan 09, 2019

What are the other Names for this Condition? (Also known as/Synonyms)

  • Simple Kidney Cyst

What is Simple Renal Cyst? (Definition/Background Information)

  • Simple Renal Cyst is a benign tumor indicating the presence of abnormal fluid-filled sacs in the kidney. It is typically seen among middle-aged and older adults
  • The cause of formation of these tumors are not well-understood, but it may be due to blockage of the kidney tubules. There are also no well-established risk factors for Simple Renal Cysts
  • Many tumors are found incidentally while examining the individual for other medical conditions. The signs and symptoms depend upon the size of the tumors and it may include abdominal pain and obstruction of the urinary tract (when cysts are large)
  • The treatment of symptomatic and large tumors may include sclerotherapy and percutaneous fluid aspiration. However, the healthcare provider may opt for a ‘wait and watch’ approach for tumors presenting no significant symptoms
  • Generally, the prognosis of Simple Renal Cyst is excellent, since it is a benign tumor. Cysts that cause hypertension, in some individuals, may be surgically drained. However, some tumors are known to recur

Who gets Simple Renal Cyst? (Age and Sex Distribution)

  • The incidence of Simple Renal Cyst increases with age; 1 in 4 over 40 years of age, and 1 in 2 individuals over age 50 years have it, according to studies
  • A predilection for males is observed, even though both male and female genders are affected
  • No specific ethnic or racial preference is seen

What are the Risk Factors for Simple Renal Cyst? (Predisposing Factors)

  • Currently, no definitive risk factors have been noted for Simple Renal Cyst

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Simple Renal Cyst? (Etiology)

  • The exact cause and mechanism of Simple Renal Cyst formation is unknown
  • Some researchers believe that it is caused by obstruction of the renal tubules (in the kidney)

What are the Signs and Symptoms of Simple Renal Cyst?

The signs and symptoms of Simple Renal Cyst depend on the size of the tumor. In general, small cystic tumors are asymptomatic and large tumors can cause significant symptoms. The signs and symptoms may include the following:

  • One or both kidneys may show the presence of these cysts (unilateral or bilateral condition)
  • The cysts are present as single or multiple fluid-filled sacs
  • The presence of these cysts usually does not change the size of the kidney, and the cysts are rarely known to affect kidney function
  • A majority of the tumors are asymptomatic, but large cysts can cause pain
  • Some studies have found that individuals with Simple Kidney Cysts may have high blood pressure (hypertension)

Note: This increased blood pressure may return to normal levels, once the cyst is aspirated/drained. However, the exact mechanism of this phenomenon is not clearly understood.

How is Simple Renal Cyst Diagnosed?

In many, Simple Renal Cysts are diagnosed incidentally during imaging studies undertaken for some other medical conditions. The diagnosis may involve the following tests and procedures:

  • Complete physical exam with evaluation of medical history
  • Plain X-ray of the abdomen
  • Ultrasound scan of the abdomen
  • CT or CAT scan with contrast of the abdomen may show a tumor mass. This radiological procedure creates detailed 3-dimensional images of structures inside the body
  • MRI scan of the abdomen: Magnetic resonance imaging (MRI) uses a magnetic field to create high-quality pictures of certain parts of the body, such as tissues, muscles, nerves, and bones. These high-quality pictures may reveal the presence of the tumor
  • Urine analysis to check for the presence of blood cells
  • Kidney function test
  • Intravenous pyelogram (IVP): A dye is injected into the blood vessels and the image of kidney structure is obtained
  • Vascular angiographic studies of the tumor

Invasive diagnostic procedures such as:

  • Laparoscopy: A special device is inserted through a small hole into the abdomen, to visually examine it. If necessary, a tissue sample is obtained for further analysis. Exploration of the abdomen using a laparoscope is called ‘exploratory laparoscopy’
  • Laparotomy: The abdomen is opened through an incision for examination, and if required, a biopsy sample obtained. Exploration of the abdomen using laparotomy procedure is called ‘exploratory laparotomy’

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include:

  • Fine needle aspiration (FNA) biopsy of the kidney tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
  • Open biopsy of the kidney tumor

Tissue biopsy:

  • A tissue biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
  • Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

Note:

  • A differential diagnosis, to eliminate other tumor types may be considered, before arriving at a conclusion
  • On radiological studies, the presence of calcification within the cysts may be observed, in some cases

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Simple Renal Cyst?

The complications of Simple Renal Cyst may include:

  • Stress and anxiety due to a concern of kidney cancer
  • Sometimes, a large cyst can obstruct the urine flow causing hydronephrosis
  • There can be bleeding within the cyst causing acute abdominal pain; a ruptured cyst may cause severe abdominal pain
  • Bleeding from the cyst may lead to hematuria (or blood in urine)
  • Some cysts may become infected, resulting in associated symptoms including fever
  • Damage to the muscles, vital nerves, and blood vessels, during surgery
  • Re-collection of fluid within the cyst after aspiration and drainage
  • Post-surgical infection at the wound site is a potential complication

How is Simple Renal Cyst Treated?

The treatment options may vary from one individual to another depending on the size of the cyst and the presence of complications, if any. The treatment measures for Simple Renal Cyst may include the following:

  • Majority of asymptomatic tumors are not surgically removed, after the tumor is determined to be benign on a biopsy. The healthcare provider may recommend a ‘wait and watch’ approach for small-sized tumors (observed during radiological studies), presenting mild signs and symptoms
  • Percutaneous aspiration of cyst fluid (to drain the fluid)
  • Sclerotherapy to collapse the cyst and prevent fluid re-accumulation within the cyst
  • Surgical intervention with complete excision can result in a cure. It can also help reduce the chances of recurrence of the cystic tumor
  • Cystectomy or partial nephrectomy, in case of a large cyst, may be recommended
  • Postoperative care is important: A minimum activity level is ensured, until the surgical wound heals

Follow-up care with regular screening may be recommended by the healthcare provider.

How can Simple Renal Cyst be Prevented?

Current medical research has not established a method of preventing Simple Renal Cyst.

  • Also, currently, there is no information to indicate that modifying one’s eating habits may help prevent the formation of these cysts
  • Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Simple Renal Cyst? (Outcomes/Resolutions)

  • The prognosis of Simple Renal Cyst is generally excellent, since it is a benign condition
  • However, in some individuals, the condition may recur (fluid may get accumulated again in the cyst)
  • Also, in some individuals, the high blood pressure may become normal after the cyst is removed/drained

Additional and Relevant Useful Information for Simple Renal Cyst:

Simple Renal Cysts are not similar to cysts observed in polycystic kidney disease (a genetic condition).

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Maulik P. Purohit MD MPH picture
Approved by

Maulik P. Purohit MD MPH

Assistant Medical Director, Medical Editorial Board, DoveMed Team

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