Background: Extra-gastrointestinal stromal tumor is defined as a mesenchymal neoplasm arising from soft tissues outside the gastrointestinal tract. Prostatic extra-gastrointestinal stromal tumor has rarely been noted.
Case Report: A 56 year-old man presented with pain in the anal region. A digital rectal examination revealed that the prostate was markedly enlarged with a smooth, bulging surface. Computerized tomography images showed a 6 cm heterogeneous, infiltrative tumor within the prostate gland extending to the trigon of the bladder, left seminal vesicle and rectum. The tru-cut biopsy of the prostate was reported as leiomyoma. It was decided to perform surgery and the masses were easily and completely removed from the adjacent structures. The case was reported as extra-gastrointestinal stromal tumor within the intermediate- risk category with free surgical margins. Four years after the surgery, a locoregional failure was observed and treated with imatinib.
Conclusion: Stromal tumor, although rare, should be considered in the differential diagnosis in patients with an enlarged prostate.

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