MTOR and neoplasm with perivascular epithelioid cell differentiation: Current research on the etiology of PEComa primarily focuses on the following (1–3): (1) mutations in tuberous sclerosis complex genes, primarily involving loss of function of the tuberous sclerosis complex 1/tuberous sclerosis complex 2 complex and resulting in increased activation of the mammalian target of rapamycin (mTOR) complex 1 and dysregulation of cell growth signals; (2) rearrangement of the TFE3 gene that may lead to carcinogenic activation by acquiring a strongly expressed promoter; and (3) rearrangement of the RAD51 paralog B gene or other rare gene fusions may play a role.