Strong association of HMB-45 expression with renal angiomyolipoma

OBJECTIVE: Angiomyolipoma (AML) is a benign neoplasm consisting of varying mixtures of smooth muscle, blood vessels and fat. Although, most of these tumors are easy to recognize, some may pose a diagnostic dilemma due to unusual histologic features. Recently, it was suggested that melanosome-associated protein (HMB-45) immunoreactivity may be used for diagnostic confirmation of several neoplasm. The aim of this study is to analyze the diagnostic efficacy of HMB-45 in patients with AML.

METHODS: This study was carried out at the Faculty of Medicine, Department of Pathology, Dicle University, Diyarbakir, Turkey, during the period January 2000 to September 2003. HMB-45 immunoreactivity was analyzed in 6 patients with AML and in 34 patients with other renal and retroperitoneal pathologies, including 10 nephrectomized patients for non-neoplastic reasons by means of immunohistochemistry.

RESULTS: Patients with AML were positive for HMB-45. Whereas, HMB-45 immunoreactivity was negative in all of the histologic specimens from the patients with renal cell carcinoma, retroperitoneal sarcomas, Wilms' tumor, lipoma, leiomyoma, and nephrectomized kidneys of non-neoplastic reason. The association of AML with HMB-45 immunoreactivity was highly significant (p<0.001).

CONCLUSION: Our findings suggest that HMB-45 may not be a melanocyte-restricted marker, and can be useful in differential diagnosis between AML and other tumors seen in kidney and retroperitoneal region.