Primary prostatic stromal sarcoma is an extremely rare disease that predominantly occurs in adults, accounting for only 0.1% of all prostate cancers. Prostatic stromal sarcoma is quite aggressive and can spread to lung, liver, bone, and other organs. Metastasis is one of the most important predictors for prognosis. Here, we reported a case of a 17-year-old adolescent boy diagnosed with primary prostatic stromal sarcoma through prostate biopsy, and stage was confirmed by F-FDG PET/CT.