The Prevalence of Prostatic Stromal Tumor of Uncertain Malignant Potential in Specimens Diagnosed as Prostatic Hyperplasia

BACKGROUND: Prostatic stromal tumors of uncertain malignant potential (STUMPs) are rare tumors arising from the specialized prostatic stroma. These tumors share certain histological and clinical features of benign prostatic hyperplasia, resulting in misdiagnosis of STUMP as prostatic hyperplasia. However, in contrast to prostatic hyperplasia, occasional cases have been documented to recur rapidly after resection and few of them have progressed to prostatic stromal sarcoma and distant metastasis. In this study, we aimed to estimate the prevalence of prostatic STUMP in specimens initially diagnosed as prostatic hyperplasia. MATHERIAL AND METHOD: A total of 702 consecutive pathology slides with a diagnosis of prostatic hyperplasia between 2009 to 2014 in specimens were obtained by prostatectomy or trans- urethral resection of the prostate. Those slides were submitted to Faghihi hospital, affiliated to Shiraz University of Medical Sciences, and were reviewed retrospectively in order to search the findings in favor of STUMP. RESULTS: Based on histological findings, STUMP was identified in 3 cases (0.43%), which revealed hypercellular stroma, infiltrating between the hyperplastic glands. Cells showed some degree of pleomorphism, nuclei with vesicular chromatin and few mitotic figures. No recurrence was reported in patients. CONCLUSION: Although STUMP can be histologically and clinically misdiagnosed as BPH, the differences in prognosis and treatment modalities highlight the importance of rendering the correct diagnosis.