Malignant perivascular epithelioid cell tumor (malignant PEComa) is a rare disease for which the diagnostic criteria and treatment options have not been established. Since PEComa is associated with upregulation of mammalian target of rapamycin (mTOR) pathway which controls Glut-1 (glucose transporter) function, increased (18)F-fluorodeoxyglucose ((18)F-FDG) uptake may indicate the over activation of mTOR pathway and may guide selectively inhibiting mTOR pathway treatment. We report a malignant PEComa patient who presented for (18)F-FDG positron emission tomography/computed tomography (PET/CT) restaging. The tumor had shown significant avidity on PET/CT as well as an evident response to sirolimus (rapamycin, Rapamune™) that supports the utility of mTOR inhibitors as an effective treatment for malignant PEComa. Therefore, (18)F-FDG PET/CT is helpful in restaging and guiding treatment for malignant PEComa with mTOR inhibitors.