Definition:

Renal angiomyolipoma (AML) is one of the most common solid benign renal tumours, composed of fat, smooth muscle, and blood vessels. About 80% of AMLs are sporadic and not associated with any genetic syndrome. Remaining cases are associated with tuberous sclerosis complex (TSC) and sporadic lymphangioleiomyomatosis (LAM). The pathogenesis of TSC is thought to result from mutations in either the TSC1 or TSC2 genes that encode the proteins tuberin and hamartin, respectively. These proteins interact with each other to form heterodimers, whose most important role is inhibition of the mTOR pathway. Loss of inhibition of mTORC1 leads to increased activation of this pathway and the formation of the lesions characteristic of TSC. Sporadic renal AML usually have mutations in TSC2, but not TSC1.