Primary extragastrointestinal stromal tumor of the prostate: review of the literature and case report.

The extragastrointestinal stromal tumor (EGIST) is defined as a mesenchymal neoplasm arising from soft tissues outside the gastrointestinal tract, and the prostate is a rare presentation site. Case presentation: A 58-year-old man was presented with lower urinary tract symptoms for 6 months. A digital rectal examination revealed a markedly enlarged prostate with a smooth, bulging surface. Prostate-specific antigen density was 0.5 ng/ml. MRI of the prostate showed an enlarged prostatic mass with hemorrhagic necrosis. Transrectal ultrasound-guided prostate biopsy was performed and pathological reports suggested a gastrointestinal stromal tumor. The patient refused radical prostatectomy and received only imatinib treatment. Clinical discussion: The diagnosis of EGIST of the prostate is extremely rare and depends on the histopathologic features with immunohistochemical results. The treatment is essentially based on radical prostatectomy, but there are other therapeutic modalities associating surgery with adjuvant or neoadjuvant chemotherapy. For patients refusing surgery, treatment with imatinib alone appears to be a therapeutic solution. Conclusion: Despite the rarity, EGIST of the prostate should be included in the differential diagnosis of patients presenting with lower urinary tract symptoms. There is no consensus regarding the treatment of EGIST, and the patients are treated as per the risk stratification.