Prostatic stromal tumor of uncertain malignant potential: a case report and literature review.

Prostatic stromal tumors, encompassing prostatic sarcoma and stromal tumors of uncertain malignant potential (STUMP), represent an exceedingly rare category of prostatic diseases, with a prevalence of less than 1%. We present a rare case involving a man in his early 40s diagnosed with STUMP. Despite presenting with normal prostate-specific antigen (PSA) concentrations, the patient experienced persistent dysuria and gross hematuria for >7 months, leading to an initial misdiagnosis of benign prostatic hyperplasia. Persistent symptoms prompted further investigation, with magnetic resonance imaging (MRI) revealing a suspicious lesion on the left side of the prostate, initially thought to be malignant. Transrectal prostatic biopsy subsequently confirmed the presence of mucinous liposarcoma, with no medical history of diabetes, coronary heart disease, or hypertension. The treatment approach comprised robot-assisted laparoscopic radical prostatectomy, culminating in a postoperative pathological definitive diagnosis of STUMP. This case underscores the indispensable role of early MRI in the diagnostic process, highlighting the necessity of detailed pathological examination for a conclusive diagnosis. Our report aims to illuminate the diagnostic challenges and potential treatment pathways for STUMP, emphasizing its consideration in the differential diagnosis of prostatic tumors to advance clinical outcomes in this rare but important condition.

Clinical and Pathological Features of Prostatic Stromal Tumor of Uncertain Malignant Potential: A Retrospective Study of 23 Chinese Cases.

INTRODUCTION: Prostatic stromal tumor of uncertain malignant potential (STUMP) is a rare disease that may coexist with prostate stromal sarcoma (PSS). We aimed to analyze the histological and clinical features of STUMP. METHODS: Twenty-three patients diagnosed with STUMP from 2008 to 2019 were included. Clinicopathological and follow-up information was collected. In the subgroup analysis, we divided the patients into a pure STUMP group (N = 18) and a mixed STUMP (STUMP coexisting with PSS) group (N = 5). Student's t test was used to compare the 2 groups. RESULTS: Patients had a mean age of 55.5 ± 19.4 years and an average follow-up time of 42.3 months. The mean prostate volume was 109.2 ± 73.5 cm3, and the mean prostate-specific antigen was 8.03 ± 10.5 ng/mL. In the subgroup analysis, 16.7% (2/12) of pure STUMP patients had disease progression, while 100% (3/3) of mixed STUMP patients suffered from recurrence. Compared with the pure STUMP group, the mixed STUMP group was younger (37.2 vs. 60.6 years, p = 0.013) and had lower expression of estrogen receptor and progesterone receptor (p = 0.004 and p < 0.001, respectively). CONCLUSION: STUMP is a rare disease with a relatively good prognosis. However, there is still a possibility of disease progression or coexistence with stromal sarcoma. Timely diagnosis and regular monitoring may be helpful in improving treatment outcomes.

[A clinical analysis of 14 cases of prostatic stromal tumor of uncertain malignant potential].

OBJECTIVE: To investigate the clinical and pathologic characteristics, diagnosis, treatment, prognosis and survival of prostatic stromal tumor of uncertain malignant potential. METHODS: Overall 14 patients with prostatic stromal tumor of uncertain malignant potential were treated from October 2008 to April 2020, the patient age ranged from 27 to 78 years (mean 54 years). The disease duration was 1 to 180 months (mean duration of 46 months). The clinical manifestations mainly included urinary obstructive symptoms and urethral irritating symptoms. The tumors were located in the peripheral zone or the transition zone. Digital rectum examination indicated prostatic tumor. Serum prostatic specific antigen level was always normal or elevated. Transrectal ultrasonography and magnetic resonance imaging indicated prostatic tumor. Magnetic resonance imaging in showed large, round, well-defined masses, which were diffusely heterogeneous signal on T2 weighted imaging. Following the administration of intravenous contrast medium, the lesion had diffuse and heterogeneous enhancement. RESULTS: In the study, 3 cases underwent prostate biopsy, 2 cases underwent transurethral resection of the prostate, 9 cases underwent radical excision or transurethral resection of the prostate with definite diagnosis of pathologic features. Under the light microscope, the interstitial cells of stromal tumor of uncertain malignant potential were overgrowth and fusiform cells showed some degree of pleomorphism, nuclei with few mitotic figures, and necrosis was not often seen. Immunohistochemical staining showed that prostate specific antigen was negative, while vimentin was positive in the tumor tissue, CD34, progesterone receptor and smooth muscle actin were positive in the majority, and Ki67 positive index was 1%-20% (mean 6%). Twelve cases were followed-up, and the time of survival varied from 10 to 96 months (mean 65 months), two cases were lost to the follow-up, one case died of disease at the end of 10 months, nine cases were free of disease recurrence after surgery, two cases underwent more transurethral resection of the prostate due to local recurrence. CONCLUSION: STUMP is a very rare tumor of the specialized prostatic stroma with an unpredictable clinical behavior. The clinical manifestations, transrectal ultrasonography and magnetic resonance imaging are valuable for the diagnosis of prostatic stromal tumor of uncertain malignant potential. Its definite diagnosis depends on pathological examination. Up to now, early surgery and combined therapy are effective treatments for prostatic stromal tumor of uncertain malignant potential.

A clinical analysis of 14 cases of prostatic stromal tumor of uncertain malignant potential / 北京大学学报(医学版)

OBJECTIVE@#To investigate the clinical and pathologic characteristics, diagnosis, treatment, prognosis and survival of prostatic stromal tumor of uncertain malignant potential.@*METHODS@#Overall 14 patients with prostatic stromal tumor of uncertain malignant potential were treated from October 2008 to April 2020, the patient age ranged from 27 to 78 years (mean 54 years). The disease duration was 1 to 180 months (mean duration of 46 months). The clinical manifestations mainly included urinary obstructive symptoms and urethral irritating symptoms. The tumors were located in the peripheral zone or the transition zone. Digital rectum examination indicated prostatic tumor. Serum prostatic specific antigen level was always normal or elevated. Transrectal ultrasonography and magnetic resonance imaging indicated prostatic tumor. Magnetic resonance imaging in showed large, round, well-defined masses, which were diffusely heterogeneous signal on T2 weighted imaging. Following the administration of intravenous contrast medium, the lesion had diffuse and heterogeneous enhancement.@*RESULTS@#In the study, 3 cases underwent prostate biopsy, 2 cases underwent transurethral resection of the prostate, 9 cases underwent radical excision or transurethral resection of the prostate with definite diagnosis of pathologic features. Under the light microscope, the interstitial cells of stromal tumor of uncertain malignant potential were overgrowth and fusiform cells showed some degree of pleomorphism, nuclei with few mitotic figures, and necrosis was not often seen. Immunohistochemical staining showed that prostate specific antigen was negative, while vimentin was positive in the tumor tissue, CD34, progesterone receptor and smooth muscle actin were positive in the majority, and Ki67 positive index was 1%-20% (mean 6%). Twelve cases were followed-up, and the time of survival varied from 10 to 96 months (mean 65 months), two cases were lost to the follow-up, one case died of disease at the end of 10 months, nine cases were free of disease recurrence after surgery, two cases underwent more transurethral resection of the prostate due to local recurrence.@*CONCLUSION@#STUMP is a very rare tumor of the specialized prostatic stroma with an unpredictable clinical behavior. The clinical manifestations, transrectal ultrasonography and magnetic resonance imaging are valuable for the diagnosis of prostatic stromal tumor of uncertain malignant potential. Its definite diagnosis depends on pathological examination. Up to now, early surgery and combined therapy are effective treatments for prostatic stromal tumor of uncertain malignant potential.

Whole-exome sequencing demonstrates recurrent somatic copy number alterations and sporadic mutations in specialized stromal tumors of the prostate.

In a previous array comparative genomic hybridization study, we detected common deletions of chromosomes 13 and 14 in prostatic stromal sarcoma and stromal tumor of uncertain malignant potential (STUMP). In this study, we performed whole-exome sequencing (WES) and fluorescence in situ hybridization to explore somatic mutations in 1 low-grade stromal sarcoma, 1 high-grade stromal sarcoma, and 12 STUMPs including 5 cases of degenerative atypia type, 1 myxoid type, 1 phyllodes type, and 5 cases of recently described round cell type. WES was successful on 13 cases that revealed frequent somatic copy number alterations including losses of chromosomes 13 (11 cases), 14 (11 cases), and 1p (9 cases), and partial or complete loss of chromosome 10 (7 cases). Fluorescence in situ hybridization was done on 9 cases and showed compatible chromosome 13 copy numbers with the WES results. STUMPs and the low-grade stromal sarcoma carried moderate tumor mutation burdens that ranged from 1.23 to 7.24 mutations per megabase, while the high-grade stromal sarcoma harbored a significantly higher mutation burden (11.55 mutations per megabase). Sporadic somatic mutations were observed, but no recurrent driver mutations could be discerned. In conjunction with prior array comparative genomic hybridization, we have demonstrated the consistent gene dosage profiles that support the clonal nature and the concept of specialized stromal tumors of the prostate as a distinctive tumor entity.