Renal angiomyolipoma: diagnosis and treatment

Abstract

Renal angiomyolipoma (RAML) is a most common benign tumor. It consists of fat, vascular, epithelioid cells, and smooth-muscle elements. Two types are described: isolated RAML and RAML associated with tuberous sclerosis. Tuberous sclerosis-associated RAML accounts for 20% of the tumors; these lesions are typically larger than RAMLs; they are often bilateral and multiple and tend to grow. The adequate diagnostic tools for RAML include ultrasonography and computed tomography. Fine-needle biopsy can elucidate the diagnosis of RAML in difficult cases. Most minor lesions are asymptomatic and those smaller than 5 cm need only a regular follow-up without intervention. Nephronsparing surgery is recommended if large RAMLs or symptomatic lesions are present. In these cases, the optimum treatment is partial nephrectomy or selective renal embolization. Angioembolization of RAML is a new technique which obviates surgical disadvantages. Positive immunoreactivity to HMB-45 and α-smooth muscle actin is diagnostic for RAML and distinguishes it from renal cell carcinoma.