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

• Neurilemoma of Kidney
• Renal Schwannoma
• Schwann Cell Tumor of Kidney

What is Schwannoma of Kidney? (Definition/Background Information)

• Schwannoma of Kidney is a rare benign tumor that arise from the Schwann cells around the nerves; these tumors are essentially nerve sheath tumors
• A schwannoma is seen among a wide range of adults and can occur at various locations in the body. But, the kidney is an uncommon location for the tumor
• The kidney consists of 2 zones; the cortex and the medulla. The cortex is the peripheral or outer portion of the kidney, and the medulla is the central or inner portion of the kidney. The tumor may be present anywhere in the kidney
• Many Schwannoma of Kidney 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 blood in urine, abdominal pain, and frequent infections affecting the urinary tract system
• Typically, a surgical excision of Schwannoma of Kidney with its entire removal is the treatment of choice. The prognosis is good with its complete removal, since it is usually a benign tumor. However, the presence of multiple tumors may adversely affect the prognosis

Who gets Schwannoma of Kidney? (Age and Sex Distribution)

• Schwannoma of Kidney is an uncommon tumor that is usually seen in adults; average age 47 years (age range 18-84 years)
• Both males and females can be affected, though some reports indicate a female predominance
• No specific ethnic or racial preference is seen

What are the Risk Factors for Schwannoma of Kidney? (Predisposing Factors)

Currently, no definitive risk factors have been noted for Schwannoma of Kidney that are solitary in nature. However, the following factors are suggested, when multiple schwannoma tumors are found in the body:

• The presence of neurofibromatosis type 2 (NF2), a genetic condition that is characterized by the formation of non-cancerous tumors that affect the nervous system. Approximately 4% of schwannomas are associated with NF2
• A family history of the tumor
• Schwannomatosis: It is a genetic condition that is a usually seen in adults and manifests as multiple schwannomas
• Gorlin-Koutlas syndrome: A complex genetic disorder of multiple tumors in the body including multiple schwannomas
• Trauma: It is often associated with plexiform schwannomas

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 Schwannoma of Kidney? (Etiology)

The exact cause and mechanism of Schwannoma of Kidney formation is unknown. Schwannomas, in general, are known to be the result of sporadic mutations. This implies that they do not have a preceding family history of the condition.

• Multiple schwannomas are known to occur in a background of genetic disorders, such as neurofibromatosis type 2 (NF2), Gorlin-Koutlas syndrome, or a positive family history
• In general, the tumor is believed to be caused by the overproduction of Schwann cells that wrap around the nerve

What are the Signs and Symptoms of Schwannoma of Kidney?

The signs and symptoms of Schwannoma of Kidney depend on the size and location of the tumor. It can vary from one individual to another. In general, small tumors are asymptomatic and large tumors can cause signs and symptoms. The kidney symptoms may be caused due to mass effect (presence of bulky tumors).

The signs and symptoms of Renal Schwannoma may include the following:

• The tumor may be present as an abdominal mass and present abdominal pain
• It is often well-defined and demarcated
• The tumors can vary in size from 4 cm to 16 cm; average size 9.7 cm
• It may be associated with frequent urinary tract infections, blood in urine, increased blood pressure, and flank pain
• Large tumors can severely affect the functioning of the kidney that is involved. Tumors growing to larger sizes can cause compression of adjoining organs and structure, but are not known to infiltrate into them

How is Schwannoma of Kidney Diagnosed?

In many, Schwannoma of Kidney is 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 well-defined 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
• Core biopsy of the kidney tumor
• 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.

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 Schwannoma of Kidney?

The complications of Schwannoma of Kidney may include:

• Stress and anxiety due to a concern of kidney cancer
• Multiple tumors may be present either in the same kidney or affecting both kidneys
• Damage to the muscles, vital nerves, and blood vessels, during surgery
• Post-surgical infection at the wound site is a potential complication

How is Schwannoma of Kidney Treated?

The treatment options vary from one individual to another. The treatment measures for Schwannoma of Kidney 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 presenting mild signs and symptoms, after a diagnosis of Renal Schwannoma is made through a fine needle aspiration or a core biopsy

Surgical excision and tumor removal is the usual mode of treatment of schwannoma. The tumor may be removed to rule out kidney cancer. The surgical treatment methods for Schwannoma of Kidney may include:

• Endoscopic surgery
• Nephron-sparing surgery
• Partial or complete nephrectomy
• Tumor embolization is a possible treatment option. Here the blood supply to the tumor is blocked resulting in its shrinkage or death

A partial or complete nephrectomy may be considered, when large-sized tumors are noted in the kidneys.

• A kidney dialysis may be required, if the kidney function is severely compromised due to renal failure
• Prompt diagnosis and emergency treatment of any abdominal (retroperitoneal) bleeding due to the tumor should be immediately considered
• Postoperative care is important: A minimum activity level is ensured, until the surgical wound heals
• Treatment of the underlying or associated conditions, if any
• Follow-up care with regular screening may be recommended by the healthcare provider

How can Schwannoma of Kidney be Prevented?

Current medical research has not established a method of preventing Schwannoma of Kidney.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks before planning for a child
• Regular medical screening at periodic intervals with tests and physical examinations are strongly recommended

What is the Prognosis of Schwannoma of Kidney? (Outcomes/Resolutions)

The prognosis of Schwannoma of Kidney depends upon the severity of the signs and symptoms. It also depends upon the overall health of the individual and response to therapy.

• The prognosis of is good, if the tumor can be removed without damaging the underlying nerve. Most schwannomas are benign and do not recur when completely excised
• Also, individuals with small-sized tumors have a better prognosis than those with larger-sized tumors
• However, this also depends upon the subtype of the tumor and the presence of neurofibromatosis type 2. If benign schwannomas transform to malignant schwannomas (on very rare occasions), then the prognosis may depend upon a set of several factors including the stage of the tumor, overall health of the individual, and response to therapy
• Asymptomatic tumors may require no treatment; unless they cause discomfort, affect the quality of life, or affect functioning of the underlying nerve. In such cases, close monitoring of the tumor is a treatment option

Additional and Relevant Useful Information for Schwannoma of Kidney:

In general, schwannomas are solitary tumors (in 90% cases) that can occur anywhere in the body, around a nerve (on the nerves of the spine or peripheral nerves of the arms and legs). The tumor can involve the spinal nerve, gastrointestinal tract, and bones (in rare cases).