Angiomyolipoma of the kidney : clinicopathological and immunohistochemical study

Abstract EN

Although angiomyolipoma (AML) is a relatively rare entity, it is the most common benign mesenchymal neoplasm of the kidney.

The aim of this study : to highlight the clinic pathological characteristics of AML and to assess the role of Human Melanoma Black-45 (HMB-45), Melan-A, smooth muscle actin (SMA), S-100 and cytokeratin in its diagnosis.

Materials and methods : the study included 15 cases of AML.

Clinical and radiological data were retrieved from the archival files and all cases were subjected to a histopathological evaluation as well as immunohistochemical staining for HMB-45, Melan-A, SMA, S-100, and cytokeratin.

Results : AML was more common in females (female : male = 4 : 1), the mean age was 6.45 ± 53.9 years.

60 % of patients were symptomatic while the remaining 40 % were asymptomatic.

A statistically significant relationship was found between size of the tumor and the presence of the symptoms (P = 0.02).

Patients with tumor size less than 4 cm were asymptomatic, while those with tumor size larger than 4 cm had different symptoms.

Thirteen cases were classic AML, while 2 cases were epithelioid AML.

Classic AML demonstrated admixture of fatty tissue, thick-walled blood vessels, and smooth muscle, while epithelioid AML was composed mainly of epithelioid cells and contained no fat.

HMB-45 was positive in all cases of AML (100 %), Melan-A was positive in 13/15 (87 %) while SMA was positive in 11/15 (73%) of AML with variable staining intensity.

All cases of AML were negative for S-100 and cytokeratin.

Conclusion : AMLs have characteristic clinicopathological and immunohistochemical features and their recognition is crucial for proper diagnosis and treatment.