Extrarenal Retroperitoneal Angiomyolipoma: A Review of the Literature

Background: Extrarenal retroperitoneal angiomyolipomas are rare.
Aim: To review the literature.
Results: Angiomyolipomas, previously classified as hamartomas, are now classified as benign
tumours. Thirty cases of primary retroperitoneal angiomyolipomas have been reported. Diagnosis of
the disease upon is based radiological and pathological findings of triphasic features of (a) fat and (b)
blood vessels and myoid tissue. Immunohistochemistry tends to be positive for HMB45, MART1,
HHF35, calponin, NKI-C3, and CD117. The lesion is common in women. Treatment options have
included the following: (a) radical surgical excision of the lesion with renal sparing surgery or radical
nephrectomy in cases where malignant tumours could not be excluded and (b) selective embolization
of the lesion alone or prior to surgical excision. One case of retroperitoneal angiomyolipoma was
reported in a patient 15 years after undergoing radical nephrectomy for angiomyolipoma of kidney and
two cases of distant metastases of angiomyolipoma have been reported following radical resection of
the tumour.
Conclusions: With the report of two cases of metastases ensuing surgical resection of the primary
lesions there is need for academic pathologists to debate and review angiomyolipomas to decide
whether to reclassify angiomyolipomas as slow-growing malignant tumours or whether the reported
cases of metastases were de novo tumours or metastatic lesions.