Renal Angiomyolipoma: A Clinicopathological Study of Seven Cases and Review of the Literature

Objective: Renal angiomyolipomas (AMLs) are mesenchymal kidney tumours that have triphasic histology. This study aimed to present the clinical, pathological and immunohistochemical features of seven AML cases along with a review of the relevant literature. Materials and Methods: Seven cases of pathologically diagnosed AML were included in the study. The presence of fat tissues, smooth muscle cells, blood vessels and epithelioid components were determined for all cases. Tumour necrosis, haemorrhage, mitosis, lymphovascular and perineural invasion were also recorded. Immune markers [human melanoma black-45 (HMB45), Melan-A, smooth muscle actin (SMA), cytokeratin], previously applied to the tissue sections, were reevaluated as positive and negative staining. Results: All cases were classic AML types. Five patients had flank pain and two had haematuria. The tumour was located in the left kidney in two cases and in the right kidney in five cases. The mean size of the AMLs was 7.36 +/- 4.23 cm. Tumours were separated from the normal kidney parenchyma with good margins and composed of mature fatty tissues, blood vessels and fusiform spindle smooth muscle cells in varying proportions. Immunohistochemically, all cases were positive with HMB-45, Melan-A and SMA. No case was positive for cytokeratin staining. Conclusion: Correct histological diagnosis of renal AML subtypes is crucial. Incorrect diagnosis of classic renal AML may lead to inadequate postoperative management. Clinicians should be aware of the malignant potential of epithelioid AML and the need for long-term follow-up.