A Clinicopathologic Study On The Stromal Tumors Of Prostate (14 Cases Report)

Prostatic stromal tumors compass a broad array of benign and malignant lesions. One subset of these lesions arises only within the prostate and generally represents entities that originate from the prostatic stroma, classified into stromal tumors of uncertain malignant potential (STUMP) and prostatic stromal sarcoma (PSS). The other subset of stromal tumors involving the prostate is also found at other sites and includes solitary fibrous tumor (SFT), smooth muscle tumor, rhabdomyosarcoma, neural tumor, gastrointestinal stromal tumor (GIST), and inflammatory myofibroblastic tumor (IMT). The majority of prostatic stromal tumors are primary tumors. These tumors are very rare, though there are varieties of tumor type. Prostatic stromal tumors are merely described as case report in papers worldwidely, because of small number of cases. Papers on these lesions are reported fewer with clinical and pathological features, except for some reports on smooth muscle tumors and stromal tumors. In the current study, we analyzed the clinicopathologic features of the cases of stromal tumors of the prostate through light microscopy observation, immunohistochemistry study, and follow-up.All tissue samples were in the pathology department of Prostate Diseases Prevention and Treatment Research Center of Jilin University and all cases have integrated clinical and epidemiologic data.Materials and methods:1. Serum PSA assay12 cases of the patients detected serum PSA level. The serum PSA level was determined using ELISA assay kit (Sweden CanAg Company).2. Digital rectal examination, DREThe prostate of all patients were detected with shape, size, and texture by using digital rectal examinations.3. BiopsyTransrectal ultrasound-guided systematic prostatic biopsies were performed on the patients using international standards 18G needle.4. HE staining and immunochemistryAll specimens were routinely fixed in 10% neutral buffered formalin and embedded in paraffin. 3μm sections, HE staining. Immunohistochemical staining of 14 cases was performed with the PV9000 method using the monoclonal antibodies against PR, CD34, bcl-2, S-100, SMA, Desmin, Myogenin, vimentin, AE1/AE3, CD117, and Ki-67 (Beijing Golden-bridge company).5. Pathological diagnostic criteria of prostatic stromal tumorsPathological diagnostic criteria of prostatic stromal tumors are adopted according to WHO (2002) edition of the urinary system and male genital tumors pathology and genetics.The results as follows:1. Detection rate of prostatic stromal tumorsFrom 2000 to January 2010, a total of 1072 specimens of needle biopsy were obtained and 14 cases of prostatic stromal tumors were diagnosed. Detection rate of prostatic stromal tumors is 1.3% (14/1072) over the 10 years. The majority of tumors are primary tumors (12/14) and secondary tumors are relatively rare (2/14).2. The clinical features of prostatic stromal tumorsPatients ranged in age from 20 to 70 years (mean 42.4 years). The major presenting signs and symptoms were urinary obstructive symptoms (n=12), hematuria (n=1), dysuria (n=1), and associated with urgency-frequency (n=2) and defecation difficulties (n=1). 14 cases of prostates were significantly large, hard or tough texture, irregular shape by digital rectal examination; and prostates showed enlargement, irregular margins, and internal uneven echo (or density) by ultrasound check and radiology imaging. One case showed prostate intruding forward into the bladder and another case showed prosrtate pressing backward rectum by radiology.3. Immunohistochemical staining results of prostatic stromal tumorsImmunohistochemical analysis was performed on a total of 14 cases of stromal tumors. All the cases expressed vimentin and were negative in AE1/AE3 and S-100. Some cases were variablely positive in PR (n=5), CD34 (n=8), bcl-2 (n=9), Myogenin (n=3), desmin (n=1) and SMA (n=1). Ki67-positive rate ranges from 1% to 30%.4. Clinicopathologic features of prostatic stromal tumors In 12 cases of prostate primary stromal tumors, there were 4 cases of prostatic specialized stromal tumors, accounting for 33.3% (4/12) and accounting for 28.6% (4/14) in all 14 cases of prostatic stromal tumors. Of 4 cases of prostatic specialized stromal tumors, 1 case was STUMP accounting for 25% (1/4) and 3 cases were stromal sarcoma accounting for 75% (3/4). 3 cases of solitary fibrous tumor accounted for 21.4% (3/14) in all 14 cases prostatic stromal tumors and accounted for 25% (3/12) in primary prostatic stromal tumors; 1 case GIST was diagnosed. The other 4 cases were spindle cell sarcoma (compatible with special stromal sarcoma). There were 2 cases secondary prostatic stromal tumors, 1 case was peritoneal malignant mesothelioma (sarcomatoid variant) and the other one was PNET arising from abdominal cavity.The conclusions as follows:(1) This study reveals that the prostatic stromal tumors are very rare neoplasm, and the majority of them are primary stromal tumors of prostate.(2) This study shows that prostatic speciliazed stromal tumor is the most common type of the prostatic stromal tumor, and solitary fibrous tumor is the second common type of the prostatic stromal tumors. Patients of the prostatic stromal tumor are generally young adult.