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

• Renal Myelolipoma

What is Myelolipoma of Kidney? (Definition/Background information)

• A myelolipoma is a rare and benign tumor consisting of fat cells and hematopoietic cells (cells that form various blood cells - RBC, WBC, platelets, etc.). The tumor name is a combination of the terms marrow (myelo-) and fat (or lipoma)
• A myelolipoma tumor is seen among a wide age range of adults and can occur at various locations in the body. But, the most common location is the adrenal gland. The kidney is an uncommon location for this tumor (the tumor by itself is a rare entity though)
• Myelolipoma of Kidney can be associated with other kidney tumors. However, the cause of its development is unknown
• The signs and symptoms of Renal Myelolipoma depend upon the size of the tumor. Large tumors may cause a mass effect with abdominal discomfort and pain. It may also rupture leading to serious complications
• Typically, a surgical excision and removal of Myelolipoma of Kidney may be undertaken for large tumors or those presenting significant symptoms. The prognosis of Myelolipoma of Kidney is generally excellent with its complete removal, since it is a benign tumor

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

• Myelolipoma of Kidney is an extremely rare tumor that is mostly observed in middle-aged and older adults (age range 40-80 years)
• Both males and females are affected and no predilection is noted
• No specific ethnic or racial preference is seen

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

• Currently, no specific risk factors have been identified for Myelolipoma of Kidney
• Renal Myelolipoma may be associated with other tumors in the kidney
• However, when it occurs in the adrenal gland, the tumor is associated with certain conditions including Cushing syndrome, Conn syndrome, and congenital adrenal hyperplasia

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 Myelolipoma of Kidney? (Etiology)

The exact cause and mechanism of Myelolipoma of Kidney formation is unknown.

What are the Signs and Symptoms of Myelolipoma of Kidney?

The signs and symptoms of Myelolipoma of Kidney may include the following:

• Most tumors are small-sized and may not exhibit any signs and symptoms
• Presence of a slowly-enlarging painless mass may be noted
• Abdominal pain and discomfort
• It may be associated with blood in urine, urinary tract infections, and increased blood pressure, in some cases
• 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 structures, but are not known infiltrate into them

How is Myelolipoma of Kidney Diagnosed?

A diagnosis of Myelolipoma of Kidney may involve the following tests and procedures:

• Complete physical exam with evaluation of medical history
• Complete blood counts with hematocrit (to detect polycythemia)
• Urine analysis to check for the presence of blood cells
• Kidney function test
• 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 scans 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
• 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

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 Myelolipoma of Kidney?

The complications of Myelolipoma of Kidney are dependent upon the size of the tumor and may include:

• Stress and anxiety due to fear of kidney cancer
• Chronic renal failure affecting kidney function if tumors are large is a potential complication
• If bleeding occurs in large tumors (that are over 4 cm in size) suddenly, it can cause retroperitoneal hemorrhage, which can result in large blood loss leading to severe shock. This is a potentially life-threatening complication requiring emergency care. In this situation, the signs and symptoms could be nausea, vomiting, back pain, sudden drop in blood pressure, and palpitations. This clinical condition is termed Wunderlich syndrome
• Damage to the muscles, vital nerves, and blood vessels, during surgery
• Post-surgical infection at the wound site is a potential complication
• Research has not conclusively proven that myelolipoma can turn malignant

How is Myelolipoma of Kidney Treated?

The treatment measures for Myelolipoma of Kidney may include the following:

• Majority of asymptomatic tumors are not surgically removed: The healthcare provider may recommend a ‘wait and watch’ approach for small-sized tumors (not more than 4 cm in size) presenting mild signs and symptoms, after a diagnosis of myelolipoma is established
• Pain medications for tumors causing pain
• Replacement of hormones (to improve hormonal balance) in case of severe adrenal gland dysfunction
• Surgical intervention with complete excision can result in a complete cure; typically, tumors over 7 cm in size or greater are surgically removed. The surgical treatment methods for Myelolipoma of Kidney may include:
  • Endoscopic surgery
  • Nephron-sparing surgery
  • Partial or complete nephrectomy
• A partial or complete nephrectomy may be considered, when large-sized tumors are noted in the kidneys
• Post-operative 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 Myelolipoma of Kidney be Prevented?

• Current medical research has not established a method of preventing Myelolipoma of Kidney
• Regular medical screening at periodic intervals with tests and physical examinations are recommended

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

• The prognosis of Myelolipoma of Kidney depends upon the size of the tumor and severity of the signs and symptoms. It also depends upon the overall health of the individual
• Typically, individuals with small-sized tumors have a better prognosis than those with larger-sized tumors. In most cases, the prognosis of the tumors is excellent with surgical intervention or appropriate treatment, since these are typically benign

Additional and Relevant Useful Information for Myelolipoma of Kidney:

Myelolipoma can occur at various locations in the body, such as the adrenal gland, mediastinum, gastrointestinal tract, and liver.