Angiomyolipoma: What is AML?

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What is AML?

AMLAngiomyolipoma is a benign (noncancerous) tumor that is most commonly found in the kidney but can also be found in other organs.  Most angiomyolipomas (AML) occur as a single lesion within the kidney.  They’re more common in women than in men presumably because of their biology.  AML has a high expression of estrogen receptors which means that they are sensitive to estrogen levels.  They are also very rare before puberty which suggests that they are hormonally responsive.

Angiomyolipomas contain thick blood vessels (angio component of the name), smooth muscle cells (myo component of the name and fat (adipose) cells (lipoma is a synonym for fat component).

Angiomyolipomas are most commonly found in middle-aged women.  Most often they are discovered incidentally on a CAT scan or kidney ultrasound.

The presence of fat within the mass on the CAT scan is usually diagnostic of angiomyolipoma.

Some angiomyolipomas are difficult diagnosis as such preoperatively and they can be confused with cancerous tumors of the kidney.  In particular, some angiomyolipomas do not have many fat cells, the so-called “fat-poor” angiomyolipomas.  These are most often diagnosed postoperatively after the tissue is removed surgically.  A percutaneous renal biopsy may help with a preoperative diagnosis.

Tuberous sclerosis (TS or TSC) and angiomyolipomas

Tuberous sclerosis is an autosomal dominant disease.  50% of patients with tuberous sclerosis will develop multiple and usually bilateral angiomyolipomas in their kidneys.  In patients with tuberous sclerosis, angiomyolipomas tend to grow faster, on average of 20% per year compared to only 5% per year for non-TS (incidental) angiomyolipomas.

Learn more about Angiomyolipoma and pregnancy.

Medical management and treatment of AML (angiomyolipoma) is a complex subject that requires consideration of multiple clinical factors.

If you have any questions, to schedule a consultation or if you need a second opinion, please contact us.  

Dr. Alex Shteynshlyuger is a board-certified urologist in NYC. He specializes in the treatment of men and women with kidney cysts, masses, renal cancer and angiomyolipoma (AML).


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