[Diagnostic difficulties in rare variants of renal angiomyolipoma]

Renal angiomyolipomas (AML) are the most common benign renal tumors. Although AML have a characteristic CT and ultrasound features, a differential diagnosis from other lipomatous tumors and renal cell carcinoma is not always possible. We present four cases of the most unusual radiological appearance of AML. Diagnostic difficulties arise in predominantly myocomponent lesions, in AML with haemorrhagic complications, in aggressive behavior of AML and coexisting renal cell carcinoma. When the diagnosis is equivocal, a fine needle aspiration biopsy is indicated. An accurate preoperative diagnosis of AML allows to avoid undesired nephrectomy and to perform preserving renal surgery in selected patients.