angiomyolipoma
Meaning of angiomyolipoma: A harmless-sounding kidney growth of fat, muscle and tangled vessels whose real danger is not spread but sudden heavy bleeding.
Definition of angiomyolipoma
An angiomyolipoma is a benign tumor made of three tissues mixed together: fat, smooth muscle and abnormal blood vessels. It grows most often in the kidney and usually causes no symptoms, so it is commonly found by chance on a scan done for another reason. Because the vessels inside it are malformed and prone to forming small bulges, larger tumors can bleed heavily.
How angiomyolipoma is built
- angi/o Combining form · Greek vessel
- my/o Combining form · Greek muscle
- lip/o Combining form · Greek fat, lipid
- -oma Suffix · Greek tumour, mass, swelling
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
Who develops one?
Two quite different groups, and the distinction shapes everything that follows.
| Feature | Occurring on its own | With tuberous sclerosis |
|---|---|---|
| Number | Usually a single tumor | Many, in both kidneys |
| Age found | Middle age and later | Childhood or early adulthood |
| Growth | Slow or static | Enlarges over time |
| Other findings | None | Skin patches, seizures, learning difficulty, lung cysts |
Tuberous sclerosis is an inherited disorder in which a brake on cell growth is faulty, so benign tumor growths appear in several organs at once. Its genetic cause explains why drugs that restore that brake can shrink the kidney tumors it produces.
Why does size matter?
The vessels running through these tumors lack a proper muscular wall and develop weak spots that can burst. Larger tumors carry more of them, and bleeding into or around the kidney can be severe enough to cause sudden flank pain, a swelling in the side and a collapse in blood pressure. That risk, rather than any tendency to spread, is what prompts treatment of a growth that is otherwise harmless. Blocking off the feeding artery from within is a common approach, and surgery that spares kidney tissue is another.
How is it told apart from a kidney cancer?
By its fat. Scanning identifies fat inside the tumor, and finding it makes the diagnosis with little further doubt, since kidney cancers almost never contain it. The difficulty comes with the minority of these tumors that hold too little fat to detect, which can look identical to a cancer on imaging and are often removed for that reason. A rare epithelioid variant is a genuine exception to the benign rule and can behave aggressively.
Also known as
Used in a sentence
Imaging showed a fat-containing lesion consistent with a renal angiomyolipoma.
Good to know
The hazard from an angiomyolipoma is hemorrhage from its malformed vessels rather than spread, and the uncommon fat-poor and epithelioid variants cannot be distinguished from kidney cancer on imaging alone.
Word origin
Where “angiomyolipoma” comes from
Assembled from the Greek angeion, meaning vessel, mys, meaning muscle, lipos, meaning fat, and the ending -oma, meaning tumor.