Definition of Angiomyolipoma

Angiomyolipoma: This is a benign (noncancerous) tumor of the kidney. An angiomyolipoma is composed of three types of cells:

1. Vascular cells ("angio-")
2. Immature smooth muscle cells ("myo-")
3. Fat cells ("lipoma")

These benign tumors are usually found in the kidney, but they occasionally occur in the liver and rarely in the ovary, fallopian tube, colon, palate, and spermatic cord. Most angiomyolipomas cause no symptoms or signs. However, even though they are benign tumors, some angiomyolipomas can cause symptoms and signs if the tumor becomes very large or if the blood vessels in the angiomyolipoma start to leak or rupture. In this case, symptoms such as back pain or flank pain, nausea, vomiting, anemia, or high blood pressure may occur. The cause of angiomyolipoma is unknown.