ABSTRACT
Angiomyolipoma is a benign lesion of the kidney characterized by proliferation of blood vessels, adipose tissue, and smooth muscle. It is associated with tuberous sclerosis. Most contain fat. If asymptomatic and <4 cm, treatment is observation. If symptomatic and/or ≥4 cm, treatment is selective embolization or surgery.
Oncocytoma is a benign lesion of the kidney that represents 3–7% of all renal tumors. On computed tomography (CT) or magnetic resonance imaging (MRI), it has a characteristic central stellate scar. Since it cannot be definitively diagnosed with abdominal imaging, and since it often coexists with renal cell carcinoma, treatment is surgery.
Retroperitoneal fibrosis is a rare fibrotic disease of the retroperitoneum that encircles and encases retroperitoneal structures. It may be idiopathic or occur secondary to inflammation, malignancy, radiation, abdominal aortic aneurysm, or medications. Initial treatment includes relief of urinary obstruction and biopsy. Subsequent treatment options include corticosteroids, tamoxifen, and ureterolysis.
