A 67-year-old woman with pleural mass underwent 18 F-FDG PET/CT, suspected of malignant pleural tumor with intense 18 F-FDG uptake. Then she underwent 68 Ga-DOTA-FAPI-04 PET/CT for staging, which showed similar uptake in pleural lesions and opposite uptake pattern in mediastinal and hilar lymph nodes. Finally, she was diagnosed with spindle cell sarcoma (G2) by histopathology. After 1 cycle chemotherapy, the pleural lesions progressed, while mediastinal lymph nodes shrunk. Half a month later, the patient died due to rapid disease progression. This case indicates that 68 Ga-FAPI PET/CT might be a promising new tool in diagnosis and staging of pleural spindle cell sarcoma.