Researchers at Iran’s Shiraz University of Medical Sciences conducted a study to estimate the prevalence of prostatic stromal tumors of uncertain malignant potential (STUMP) — rare tumors that share certain histological and clinical features with benign prostatic hyperplasia (BPH) — in a sample of patients initially diagnosed with BPH.

The research paper, “The Prevalence of Prostatic Stromal Tumor of Uncertain Malignant Potential in Specimens Diagnosed as Prostatic Hyperplasia,” was published in Archives of Iranian Medicine.

STUMPs are rare lesions that arise from prostate cells and can have distinct clinical outcomes, from never progressing to turning out to be highly aggressive lesions that lead to invasive metastasis and death.

Due to their lack of specificity, the clinical and microscopic features of STUMP may closely mimic those of BPH. But it is important to correctly diagnose this condition due to the possibility that it may progress to a malignant tumor, and the need for adequate treatments. Because of the rarity of such lesions, few studies have been conducted where the clinical or microscopic features of these lesions are described.

To evaluate the prevalence of STUMP in patients initially diagnosed with BPH, researchers investigated 702 pathology slides obtained by prostatectomy or transurethral resection of the prostate (TURP) from 2009 to 2014. All slides were reviewed and evaluated by a pathologist

According to the results, three (0.43 percent) of the 702 examined cases received a diagnosis of STUMP, based on histological examinations. No evidence was found of recurrence, progression, or metastasis of the disease for these patients after TURP or prostatectomy.

The researchers further described the morphological and histological features that show the difference between STUMP and other conditions, especially BPH, and highlight how readily some cellular features of STUMP can also be observed in BPH.

Among other features, STUMPs are usually located at the peripheral zone of the prostate and can occur in younger patients.

“In 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,” the researchers said.