The role of the TSC genes in the pathogenesis of sporadic PEComa has still to be elucidated, but recent data suggest that small deletions or mutations (inactivating or missense) in genes TSC1 or TSC2 may account for loss of TSC2 expression in those tumors [5,13]. This evidence concerns the gene TSC2 and neoplasm with perivascular epithelioid cell differentiation.