Renal angiomyolipoma: Report of three cases with regional lymph node involvement and/or with renal cell carcinoma

Aims and background: Angiomyolipomas (AMLs) are benign hamartoid tumors which frequently occur in tuberous sclerosis (TS), They may be manifest at different organ sites such as kidneys, lymph nodes, liver and lung and may be associated with renal cell carcinoma (RCC), The nature of multiple organ involvement in AML (metastasis versus multicentric synchronous tumors), the malignant transformation and the relation of AML to RCC have not been sufficiently clarified, Study design: Three cases of renal AMLs in patients with tuberous sclerosis associated with lymphangioleiomyomatosis of the paraaortic lymph nodes and/or with RCC are reported, The concise clinical history of the patients as well as the findings of histology, immunohistochemistry and quantitative DNA analysis are presented, Results: The multicentric form of AML and coincidence of renal AML and RCC were observed in 2 patients, AML and RCC were found within the same focus in one of the cases, RCCs were either aneuploid or ''near diploid'', whereas one of the multicentric AMLs showed a discordant DNA ploidy pattern, namely aneuploidy in the kidney and diploidy in the lymph nodes. Conclusions: The presented cases (all of them underwent periaortic lymphadenectomy) suggest that lymph node involvement in renal AML may be more frequent than expected (1-2% of all AMLs) on the basis of the few reported cases. The discordant DNA ploidy (renal versus lymph node lesions) observed in one of the cases with multicentric AML implies synchronous tumor growth at different sites rather than metastatic disease, The intimate coexistance of RCC and AML (RCC revealed by immunohistochemistry within a larger mass of renal AML) may indicate that malignant transformation of an AML should only be accepted, if such a coincidence is unequivocally excluded.