Myelolipoma

Myelolipoma
An adrenal myelolipoma
Classification and external resources
Specialty	oncology
ICD-10	D17
ICD-O	M8870/0
eMedicine	radiology/genitourinary/376700
MeSH	D018209
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Myelolipoma (myelo-, from the ancient greek μυελός, marrow; lipo, meaning of, or pertaining to, fat; -oma, meaning tumor or mass) is a benign tumor-like lesion composed of mature adipose (fat) tissue and haematopoietic (blood-forming) elements in various proportions.

Myelolipomas can present in the adrenal gland, or outside of the gland.

Although several hypotheses have been proposed as to the cause of myelolipoma, the causative process is still not clearly understood. Recent experimental evidence suggests that both the myeloid and lipomatous elements have a monoclonal origin, which strongly supports the hypothesis that myelolipomas are neoplastic lesions.

Older theories proposing a non-neoplastic origin include the following:

Myelolipomas are rare. They have been reported to be found unexpectedly at autopsy in 0.08% to 0.4% of cases (i.e.: somewhere between 8 per 10,000 and 4 per 1,000 autopsies). They most commonly occur in the adrenal gland, yet only comprise about 3% of all adrenal tumours. They may also occur in other sites, such as the mediastinum, the liver and the gastrointestinal tract.

There is no gender predilection, males and females are affected equally. The peak age range at diagnosis is between 40 and 79 years of age.

The majority of myelolipomas are asymptomatic. Most do not produce any adrenal hormones. Most are only discovered as a result of investigation for another problem.

When myelolipomas do produce symptoms, it is usually because they have become large, and are pressing on other organs or tissues nearby. Symptoms include pain in the abdomen or , blood in the urine, a palpable lump or high blood pressure.

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