Composite Renal Cell Carcinoma and Angiomyolipoma: A Rare Case and Possible Diagnostic Pitfalls

Abstract Angiomyolipomas are benign renal neoplasms commonly associated with tuberous sclerosis complex (Semin Diagn Pathol 1998;15(1):21–40). However, angiomyolipoma with concurrent renal cell neoplasia is very uncommon, with fewer than 50 reported cases. Even less common is direct admixture of renal cell carcinoma (RCC) and angiomyolipoma within 1 tumor mass, with only rare possible cases reported in the literature. A multi-institutional study of 36 cases of synchronous renal cell neoplasm and angiomyolipoma found that clear cell RCC was the most common concurrent cancer in patients with sporadic or tuberous sclerosis-associated angiomyolipoma; angiomyolipoma in these cases was incidental (Mod Pathol 2001;14(3):157–163). Here, we report the exceptionally uncommon occurrence of a composite RCC and angiomyolipoma, occurring as an intimate admixture within a single tumor mass.