Update on the Diagnosis and Management of Renal Angiomyolipoma

Abstract

Purpose: Advances in minimally invasive therapies and novel targeted chemotherapeutics have provided a breadth of options for the management of renal masses. Management of renal angiomyolipoma has not been reviewed in a comprehensive fashion in more than a decade. We provide an updated review of the current diagnosis and management strategies for renal angiomyolipoma.

Materials and methods: We conducted a PubMed(®) search of all available literature for renal or kidney angiomyolipoma. Further sources were identified in the reference lists of identified articles. We specifically reviewed case series of partial nephrectomy, selective arterial embolization and ablative therapies as well as trials of mTOR inhibitors for angiomyolipoma from 1999 to 2014.

Results: Renal angiomyolipoma is an uncommon benign renal tumor. Although associated with tuberous sclerosis complex, these tumors occur sporadically. Risk of life threatening hemorrhage is the main clinical concern. Due to the fat content, angiomyolipomas are generally readily identifiable on computerized tomography and magnetic resonance imaging. However, fat poor angiomyolipoma can present a diagnostic challenge. Novel research suggests that various strategies using magnetic resonance imaging, including chemical shift magnetic resonance imaging, have the potential to differentiate fat poor angiomyolipoma from renal cell carcinoma. Active surveillance is the accepted management for small asymptomatic masses. Generally, symptomatic masses and masses greater than 4 cm should be treated. However, other relative indications may apply. Options for treatment have traditionally included radical and partial nephrectomy, selective arterial embolization and ablative therapies, including cryoablation and radio frequency ablation, all of which we review and update. We also review recent advances in the medical treatment of patients with tuberous sclerosis complex associated angiomyolipomas with mTOR inhibitors. Specifically trials of everolimus for patients with tuberous sclerosis complex suggest that this agent may be safe and effective in treating angiomyolipoma tumor burden. A schema for the suggested management of renal angiomyolipoma is provided.

Conclusions: Appropriately selected cases of renal angiomyolipoma can be managed by active surveillance. For those patients requiring treatment nephron sparing approaches, including partial nephrectomy and selective arterial embolization, are preferred options. For those with tuberous sclerosis complex mTOR inhibitors may represent a viable approach to control tumor burden while conserving renal parenchyma.

Keywords: TOR serine-threonine kinases; angiomyolipoma; embolization, therapeutic; nephrectomy; tuberous sclerosis.