Epidermal Growth Factor Receptor Positivity in Angiomyolipoma Contiguous to Renal Cell Carcinoma: Report of Two Cases with Immunohistochemical Analysis

Renal cell carcinoma (RCC) and angiomyolipoma (AML), usually unassociated, have occasionally been reported to coexist in the same person, usually in patients with tuberous sclerosis. We report two patients without tuberous sclerosis whose nephrectomy specimens contained renal cell carcinoma directly contiguous to AML in the same kidney. When immunohistochemical staining for epidermal growth factor receptor (EGFR) was performed on the RCCs, an interesting observation was made. The contiguous AMLs demonstrated strong positivity for EGFR, a feature not observed in isolated AMLs. The significance of this finding is unclear. Paracrine regulation may exist between these two closely adjacent tumors leading to synchronous high expression of EGFR in the AML adjacent to RCC, which may in turn affect the biologic behavior of these AMLs, compared to AMLs not associated with RCC.