Prostatic Solitary Fibrous Tumor With Pulmonary Metastases: A Case Report

Solitary fibrous tumors (SFT) are rare intermediate-grade mesenchymal neoplasms with unpredictable clinical courses, including the potential for late metastases. While most commonly arising in the pleura, extrapleural SFTs have been described. However, SFTs originating from the prostate are exceptionally rare, and their potential for metastatic progression remains largely unknown. A 59-year-old male presented with lower urinary tract symptoms and underwent Holmium laser enucleation of the prostate (HoLEP) after unsuccessful medical therapy. Histopathological examination revealed spindle-shaped neoplastic cells that were positive for cluster of differentiation 34 (CD34) and signal transducer and activator of transcription 6 (STAT6), confirming SFT. Radical prostatectomy was subsequently performed with negative surgical margins. Twenty-three months later, thoracic imaging detected two pulmonary nodules. Fibroblast activation protein inhibitor (FAPI) positron emission tomography (PET) and percutaneous biopsy confirmed metastatic SFT. Both lung lesions were surgically resected, followed by adjuvant chemotherapy with ifosfamide and doxorubicin. The patient has remained in remission for 18 months. This case emphasizes that even histologically benign-appearing prostatic SFTs can demonstrate malignant potential. It also underscores the necessity of long-term surveillance and contributes to the literature by reporting the first known case of a metastatic SFT originating from the prostate gland.