TSC1 and neoplasm with perivascular epithelioid cell differentiation: Molecularly, most PEComas, including sporadic ones, are defined by a loss of function of the TSC1/TSC2 complex, in the majority of the cases the result of a loss of heterozygosity (LOH) in the TSC2 gene, leading to increased mTORC1 activation and deregulated cell growth signaling [5, 8, 14].