Furthermore, thing in a recent study by Ramon et al.(9) rates of post-embolization syndrome (i.e. fever and flank pain) were significantly lower as compared with other reports in the literature (9). In the same study by Ramon et al.(9) patients initially treated with SAE were followed up for a mean of 4.8 years, during which no symptoms such as pain or bleeding occurred. Nevertheless, repeat embolization was needed in about 37% of cases due to neoangiogenesis or re-canalization of treated vessels. No deaths have been described in relation to embolization treatment, and kidney function remains nearly unaltered after the intervention. Therefore, SAE is a minimally invasive procedure that is associated with optimal preservation of renal function (9). Alternatively, a partial nephrectomy can be performed.

This approach has higher complication rates (24), although it is associated with a lower incidence of recurrence as compared with SAE (9). Drugs such as mTOR inhibitors (10) and anti-angiogenic agents (25) represent a non-invasive therapeutic option with a lower incidence of complications for the treatment of asymptomatic AML patients in whom SAE or nephron sparing surgery (NSS) (22) are difficult to perform. Due to high morbidity related to the possible occurrence of renal insufficiency, radical nephrectomy is indicated only for the treatment of AMLs >8 cm (22), when suspicion of malignancy is high and when minimally invasive techniques cannot be performed (11). Conclusions Renal angiomyolipoma is a benign kidney tumour with hamartomatous features.

Retroperitoneal haemorrhage is the most frequent complication of AML. Among possible treatments, super-selective embolization of segmental arteries that supply the lesion is considered as the most effective minimally invasive approach in preventing haemorrhagic events and symptomatic manifestations. This procedure is advisable for AMLs with a diameter >4 cm. The procedure is well tolerated and is associated with minor complications, although it has been associated with frequent relapses as compared with surgical alternatives.
Angiomyolipoma (AML) is a rare mesenchyme-derived neoplasm that is primarily composed of adipose tissue, smooth muscle, and abnormal blood vessels, in variable proportion and is part of the perivascular epithelioid cell (PEC) tumor family known as PEComas (1, 2). Typical AML morphology have been reported in several sites outside the kidney and the liver, including lung, retroperitoneum, uterus, ovary, vagina, penis, spinal cord, bladder, bone, heart, nasal cavity, skin and GSK-3 colon. The epithelioid variant of AML is composed of a predominant or exclusive population of epithelioid cells.