The role of imaging techniques in diagnostic evaluation of angiomyolipomas.

Renal AML are rare benign tumors of the kidneys consisting of fat tissue intermixed with thick-walled blood vessels and smooth muscle. Due to the easy access to modern imaging techniques more and more AML are detected incidentally during diagnostic evaluation of common urological disease before getting symptomatic (mostly flank pain, hematuria). The presence of a highly echodense renal mass on ultrasound and the detection of even small amounts of fat in CT usually allows to establish the diagnosis of AML. If these procedures give still equivocal results, angiography and MRI may become necessary. When report a case of a patient with AML where all the imaging techniques including magnetic resonance were nonconclusive. The correct diagnosis could only be established by histological examination after surgical resection. Indeed, the presence of a large hematoma had masked all the characteristic features of AML in this case.