Alveolar soft part sarcoma (ASPS) is a rare malignant soft tissue tumor. We present a case, who had a history of a left pulmonary ASPS resection 5 years ago, with a tumor in the left lower extremity showing high vascularity mimicking hemangioma on enhanced CT and MRI. This tumor showed intense FDG uptake on FDG PET/CT with SUVmax of 6.8, indicating a malignant soft tissue tumor. Complete resection of the tumor was performed. A diagnosis of ASPS was confirmed by pathology. This case highlights FDG PET/CT is helpful for differentiating ASPS from hemangioma according the degree of FDG uptake.