Cancers with higher rates of TSC1/TSC2 mutation include: urothelial carcinoma of the bladder and upper tract, with 6–10% incidence of TSC1 mutations [5] and perivascular epithelioid cell tumors (PEComa) with up to 50% frequency of TSC2 and TSC1 mutations [6]. The gene discussed is TSC1; the disease is neoplasm with perivascular epithelioid cell differentiation.