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

• Benign Tumor of Fat and Hematopoietic Tissue

What is Myelolipoma? (Definition/Background Information)

• A Myelolipoma is a rare and benign tumor consisting of fat cells and hematopoietic tissue 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. The most common location is the adrenal gland (about 85% of the cases). The other uncommon sites include the mediastinum, gastrointestinal tract, liver, and kidney; retroperitoneal tumors account for 12% of the cases
• The risk factors for Myelolipoma are not well-established, and the cause of tumor formation is unknown. Many tumors are found incidentally, while examining the individual for other medical conditions
• The signs and symptoms of Myelolipoma depend upon the site and size of the tumors. Large tumors may cause a mass effect with abdominal discomfort and pain. It may also rupture leading to bleeding and serious complications
• Typically, a surgical excision and removal of Myelolipoma may be undertaken for large tumors or those presenting significant symptoms. The prognosis of Myelolipoma is generally excellent with its complete removal, since it is a benign tumor

Who gets Myelolipoma? (Age and Sex Distribution)

• Myelolipoma is a 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? (Predisposing Factors)

• Currently, no specific risk factors have been identified for Myelolipoma
• A few risk factors have been defined based on the location of the tumor

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? (Etiology)

The exact cause and mechanism of Myelolipoma formation is unknown.

What are the Signs and Symptoms of Myelolipoma?

The signs and symptoms of Myelolipoma depend on the location of the tumor and 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
• The size of the tumor may range from a few mm to over 34 cm (average size range is between 2-10 cm)
• Abdominal pain and discomfort
• Large tumors can severely affect the functioning of the organ 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 Diagnosed?

A diagnosis of Myelolipoma 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
• 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
• 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 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 tumor
• Open biopsy of the 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?

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

• Stress and anxiety due to fear of abdominal cancer (or at other locations)
• Organ dysfunction that may occur from large tumors
• If bleeding occurs in large tumors 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 Treated?

The treatment measures for Myelolipoma 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
• Surgical intervention with complete excision can result in a complete cure; typically, tumors over 7 cm in size or greater are surgically removed
• 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 be Prevented?

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

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

• The prognosis of Myelolipoma depends upon the size of the tumor, the location 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:

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