[A Case of Malacoplakia of the Prostate which was Difficult to Distinguish from Prostate Cancer].

A 70-year-old-man was referred with urination pain and pyuria. Prostate specific antigen was 10.6 ng/ml, and urine culture was Escherichia coli. The abdominal ultrasonography showed irregular low echo at the right lobe of prostate. Prostate magnetic resonance imaging (MRI) showed an extracapsular infiltrated prostate tumor in the right lobe. Levofloxacin was administered and prostate biopsy was performed. The pathological examination revealed that the prostate tissue was filled with inflammatory cells and had lost its glandular duct structure. The patient was diagnosed with malacoplakia of the prostate. Four months after prostate biopsy, prostate MRI imaging showed disappearance of the extracapsular infiltration in right peripheral zone.

Detection of von Hippel-Lindau gene mutation in circulating cell-free DNA for clear cell renal cell carcinoma.

The therapeutic landscape of metastatic clear cell renal cell carcinoma (ccRCC) has rapidly expanded, and there is an urgent need to develop noninvasive biomarkers that can select an optimal therapy or evaluate the response in real time. To evaluate the clinical utility of circulating tumor DNA (ctDNA) analysis in ccRCC, we established a highly sensitive assay to detect mutations in von Hippel-Lindau gene (VHL) using a combination of digital PCR and multiplex PCR-based targeted sequencing. The unique assay could detect VHL mutations with a variant allele frequency (VAF) <1.0%. Further, we profiled the mutation status of VHL in 76 cell-free DNA (cfDNA) and 50 tumor tissues from 56 patients with ccRCC using the assay. Thirteen VHL mutations were identified in cfDNA from 12 (21.4%) patients with a median VAF of 0.78% (range, 0.13%-4.20%). Of the 28 patients with VHL mutations in matched tumor tissues, eight (28.6%) also had VHL mutation in cfDNA with a median VAF of 0.47% (range, 0.13%-2.88%). In serial ctDNA analysis from one patient, we confirmed that the VAF of VHL mutation changed consistent with tumor size by radiographic imaging during systemic treatment. In conclusion, VHL mutation in cfDNA was detected only in a small number of patients even using the highly sensitive assay; nevertheless, we showed the potential of ctDNA analysis as a novel biomarker in ccRCC.

[A Case of Prostatic Cancer that Had Bilateral Ureteral Metastases at Initial Diagnosis].

Ureteral metastases from prostate cancer are uncommon. We report a case of prostate cancer with bilateral ureteral metastases. A 76-year-old man visited our hospital because of serum prostate specific antigen (PSA) level of 40.7 ng/ml. Contrast-enhanced computed tomography revealed bilateral ureteral tumors causing bilateral hydronephrosis. Magnetic resonance imaging and prostate biopsy showed prostate cancer involving the bladder neck with bone metastases. Voided urine cytology suggested urothelial carcinoma. Retrograde pyelography demonstrated left ureteral filling defect and right lower ureteral stenosis. Left ureteral tumor and concomitant prostate cancer were suspected ; thus, combined androgen blockade therapy was initiated, and left nephroureterectomy was subsequently performed. Pathological and immunohistochemical examination of the left ureteral tumor revealed PSA-positive adenocarcinoma. The contralateral ureteral lesion was presumed to be metastasis from the same origin ; hence, prostate cancer with bilateral ureteral metastases was diagnosed. Although the mechanism is unknown, ureteral metastasis should be considered in the differential diagnosis of prostate cancer patients with ureteral tumor.

[Complete Transurethral Resection of Large Non-Muscle-Invasive Bladder Cancer Preoperatively Suspected to Be Muscle-Invasive Disease : A Case Report and Literature Review].

A 69-year-old man presented with gross hematuria. Cystoscopy revealed a large papillary tumor occupying the bladder. Magnetic resonance imaging showed a large bladder tumor more than 8cm in maximum diameter,suspected to be muscle-invasive disease. We performed the 1st transurethral resection of bladder tumor (TURBT) for the main purpose of pathological confirmation. Histopathological findings of the resected specimens showed urothelial carcinoma,low grade pTa. We performed subsequent treatments with TURBT twice,resulting in complete resection. The histopathological findings showed the same results as those of the 1st TURBT conclusively,which was consistent with non-muscle-invasive bladder cancer. He received intravesical instillation of pirarubicin eight times in total and has remained free from recurrence for more than 26 months after the final TURBT.

[A Case of Primary Ewing Sarcoma of the Kidney Treated with Multidisciplinary Approach].

A woman in her 40s visited our hospital for further examination and treatment of a left renal tumor. Imaging studies showed that the patient had a large left renal tumor, 10.5 cm in diameter, which contained foci of necrosis. Open left radical nephrectomy was performed. In pathological examination, hematoxylin-eosin staining showed uniform small round cells with alveolar growth. Immunohistochemistry findings showed that CD99 and NKX2. 2 were positive, and synaptophysin was focally positive. Fluorescence in situ hybridization confirmed (11 ; 22) (q24 ; q12) chromosomal translocation which led to diagnosis of primary Ewing sarcoma of the kidney. Two months after the surgery, new tumors were found inside and outside of the left psoas muscles and in the left paracolic gutter. Six courses of chemotherapy were administered with VDC (vincristine/doxorubicin/cyclophosphamide) and IE (ifosfamide/etoposide). After completing the combined chemotherapy, the recurrent tumors disappeared completely on imaging. To prevent further recurrence, external radiation was administered to the left retroperitoneal region. About 16 months after the surgery, numerous new tumors appeared in the left retroperitoneal, left pleura, and erector spinae muscles. Chemotherapy was resumed following radiotherapy, and then trabectedin was administered. However, she eventually died of progressive disease at 26 months after the surgery.

Downregulation of RalGTPase-activating protein promotes invasion of prostatic epithelial cells and progression from intraepithelial neoplasia to cancer during prostate carcinogenesis.

RalGTPase-activating protein (RalGAP) is an important negative regulator of small GTPases RalA/B that mediates various oncogenic signaling pathways in various cancers. Although the Ral pathway has been implicated in prostate cancer (PCa) development and progression, the significance of RalGAP in PCa has been largely unknown. We examined RalGAPα2 expression using immunohistochemistry on two independent tissue microarray sets. Both datasets demonstrated that the expression of RalGAPα2 was significantly downregulated in PCa tissues compared to adjacent benign prostatic epithelia. Silencing of RalGAPα2 by short hairpin RNA enhanced migration and invasion abilities of benign and malignant prostate epithelial cell lines without affecting cell proliferation. Exogenous expression of wild-type RalGAP, but not the GTPase-activating protein activity-deficient mutant of RalGAP, suppressed migration and invasion of multiple PCa cell lines and was phenocopied by pharmacological inhibition of RalA/B. Loss of Ralgapa2 promoted local microscopic invasion of prostatic intraepithelial neoplasia without affecting tumor growth in a Pten-deficient mouse model for prostate tumorigenesis. Our findings demonstrate the functional significance of RalGAP downregulation to promote invasion ability, which is a property necessary for prostate carcinogenesis. Thus, loss of RalGAP function has a distinct role in promoting progression from prostatic intraepithelial neoplasia to invasive adenocarcinoma.

[A Case of Metastatic Mucinous Adenocarcinoma Derived from the Right Ovary to the Ileal Ureter].

A 76-year-old woman presented with temporary right back pain and renal dysfunction. She had undergone ileal ureter interposition for right ureteral resection due to retroperitoneal liposarcoma about forty years ago. Abdominal computed tomographic (CT) scan showed right hydronephrosis and a stenosis in the middle of the ileal ureter. The symptoms were relieved, and the patient was followed. Six months later, however, a contrast enhanced lesion was newly observed at the stenosis of the ileal ureter, and nineteen months later, right ovarian tumor and peritoneal dissemination were subsequently observed. Aiming at diagnosis and cytoreduction, right nephroureterectomy and bilateral oophorectomy were performed. Histopathological findings of the resected tumors showed common characteristics of infiltrating and proliferating adenocarcinoma. Immunohistochemistry findings showed that Cytokeratin 7 and Cytokeratin 20 stained positive. On the other hand, Mucin 2 and Special AT-rich sequence-binding protein 2 were not found. The histopathological diagnosis was metastatic mucinous adenocarcinoma of the ovary with ileal ureter and a wide peritoneal dissemination. The patient rejected adjuvant chemotherapy and a new lesion was found in the pelvic fourmonths afterthe surgery.

[A Case of Malignant Lymphoma with an Elevated Serum IgG4].

A man in his 60s was referred to our hospital for further examination of left hydronephrosis and renal dysfunction. An enhanced abdominal computed tomographic scan showed that the patient had chronic abdominal aortic dissection and a non-enhancing retroperitoneal soft tissue occupying the front of the abdominal aorta as well as the bilateral common iliac arteries. The left ureter was compressed by the soft tissue at the fourth lumbar level. No tumor markers were significantly elevated and idiopathic retroperitoneal fibrosis was suspected to be the cause. Before starting treatment, however, right hydronephrosis was newly observed. We placed bilateral ureteral stents and reviewed our diagnosis. Elevated serum IgG4 and accumulation of 18F-fluorodeoxyglucose in the soft tissue were the points at issue. To determine the diagnosis, we performed open wedge biopsy. Histopathological findings showed mainly fibrous connective tissue with lymphocytic infiltration, which was positive for CD10, CD20, and bcl-2. These findings indicated follicular lymphoma. Induction chemotherapy was performed with 6 cycles of rituximab/cyclophosphamide/vincristine/prednisolone. The soft tissue tumor shrank markedly and the patient has been free from bilateral ureteral stents.

Amino-terminal enhancer of split gene AES encodes a tumor and metastasis suppressor of prostate cancer.

A major cause of cancer death is its metastasis to the vital organs. Few effective therapies are available for metastatic castration-resistant prostate cancer (PCa), and progressive metastatic lesions such as lymph nodes and bones cause mortality. We recently identified AES as a metastasis suppressor for colon cancer. Here, we have studied the roles of AES in PCa progression. We analyzed the relationship between AES expression and PCa stages of progression by immunohistochemistry of human needle biopsy samples. We then performed overexpression and knockdown of AES in human PCa cell lines LNCaP, DU145 and PC3, and determined the effects on proliferation, invasion and metastasis in culture and in a xenograft model. We also compared the PCa phenotypes of Aes/Pten compound knockout mice with those of Pten simple knockout mice. Expression levels of AES were inversely correlated with clinical stages of human PCa. Exogenous expression of AES suppressed the growth of LNCaP cells, whereas the AES knockdown promoted it. We also found that AES suppressed transcriptional activities of androgen receptor and Notch signaling. Notably, AES overexpression in AR-defective DU145 and PC3 cells reduced invasion and metastasis to lymph nodes and bones without affecting proliferation in culture. Consistently, prostate epithelium-specific inactivation of Aes in Ptenflox/flox mice increased expression of Snail and MMP9, and accelerated growth, invasion and lymph node metastasis of the mouse prostate tumor. These results suggest that AES plays an important role in controlling tumor growth and metastasis of PCa by regulating both AR and Notch signaling pathways.

[A Case Report : Metastatic Carcinoma of the Collecting Ducts of Bellini in a Hemodialysis Patient Treated with Temsirolimus].

Carcinoma of the collecting ductsof Bellini isa rare histological subtype of renal cell carcinoma and mostly has unfavorable prognosis. Radical nephrectomy is generally chosen for the 1st line treatment but therapeutic approaches for the metastasis/recurrence have not been established. We report a case of carcinoma of collecting ducts of Bellini in a patient receiving hemodialysis treated with temsirolimus. A 62- year-old man receiving hemodialysis was admitted to our hospital with drug-resistant anemia and high-grade cyclic fever. Computed tomography revealed the right renal tumor and multiple metastatic lung tumors. Open radical nephrectomy wasperformed. Pathological findingswere compatible with carcinoma of the collecting ducts of Bellini. He was given weekly temsirolimus treatment. The disease progressed modestly but kept the stable disease (SD) status for six months. He died of the cancer 11 months after the initial diagnosis.

[The Efficacy of a Released Ultrasonic Lithotripsy in Percutaneous Nephrolithotomy : Randomized Trial Comparing Swiss LithoClast® Master Versus Swiss LithoClast®].

We prospectively randomized total 29 patients with renal stones into two groups between Aug 2014 and March 2016. The US group was treated using a ultrasonic lithotripter (Swiss LithoClast® Master) and the PN group was treated with a pneumatic lithotripter (Swiss LithoClast® ). We compared treatment outcomes in these groups. The US group consisted of 17 patients and the PN group 12 patients. There was no significant difference between the groups in baseline characteristics (age, sex, body mass index, side, stone size, and density). There was no significant difference in total operative time (p＝0.63), stone-free rate (p＝ 0.19), hemoglobin deficit (p＝0.49), or rate of postoperative sepsis (p＝0.99) between the two groups. However, intracorporal stone disintegration and removal time was significantly shorter in the US group than the PN group (p＝0.029). These results suggest that the ultrasonic lithotripter can be superior to the existing pneumatic lithotripter in saving intracorporal stone disintegration and removal time in percutaneous nephrolithotomy.

LAPAROSCOPIC RADICAL NEPHRECTOMY FOR RENAL TUMOR>7CM.

(Objectives) Laparoscopic radical nephrectomy (LRN) is now a standard care for the treatment of renal tumors, but the limitation of LRN for large tumors remains to be elucidated. In this study, we examined the safety and efficacy of LRN for >7 cm renal tumors including tumors >10 cm. (Patients and methods) From March 2001 to September 2014, 167 patients received laparoscopic surgery for renal tumors at our institution. Of these, 126 patients (≤4.0 cm: 64 cases, 4.1-7.0 cm: 40 cases, 7.1-10.0 cm: 12 cases, >10.0 cm: 10 cases) underwent LRN. Treatment outcomes including surgical and oncological outcomes among each stage were compared. (Results) Operating time for 7.1-10.0 cm tumors were similar to that <7 cm tumors but that for >10 cm tumors was significantly longer than that <10 cm tumors. There was no significant difference among each stage in terms of complication rate. As expected, recurrence-free survival rate for >10 cm tumors were worse than <10 cm tumors. (Conclusions) Our data suggests that LRN for large tumors >7 cm can be performed safely, but LRN for >10 cm tumors are technically demanding and require longer operation time.

MID-TERM ONCOLOGICAL OUTCOME AND TECHNICAL MODIFICATIONS FOR LAPAROSCOPIC RADICAL CYSTECTOMY AT OUR INSTITUTION: 60 CASES ANALYSIS.

(Objective) Although laparoscopic radical cystectomy (LRC) is becoming a standard care for invasive and high-risk non-invasive bladder cancer in Japan, the data about mid-and long-term oncological outcome is still lacking. We previously reported our initial experience of LRC compared to open radical cystectomy. In this study, we evaluated mid-term oncological outcome for LRC by updating our clinical data. In addition, we evaluated the effect of technical modifications for LRC. (Patients and methods) From March 2005 to September 2015, 60 patients underwent LRC at our institution. Treatment outcomes including surgical and oncological outcomes were analyzed. We also assessed the effect of technical modifications between first 30 cases and second 30 cases as to blood loss, operating time and complication rate. (Results) The overall complication rate was 47%, including 18% serious complications (Clavien score 3 or greater). The 5-year recurrence-free survival, cancer-specific survival, and overall survival were 56.2%, 74.4%, and 63.6%, respectively. The recurrence occurred in 19 (32%) cases, including distant metastasis in 12 (20%) cases, local recurrence in 6 (10%) cases, and both in 1 (2%) cases. As for the effect of technical modifications for LRC, the blood loss decreased and postoperative recovery was faster in second 30 cases. (Conclusion) These results indicate that LRC could be performed safely with acceptable oncological outcomes.

THE FACTORS THAT AFFECT THE DECISION TO PERFORM LAPAROSCOPIC PARTIAL NEPHRECTOMY FOR SMALL RENAL TUMOR.

(Objectives) Nephron sparing surgery (NSS) is strongly recommended for patients with T1a renal cell carcinoma (RCC) whenever surgically feasible. However, partial nephrectomy, particularly laparoscopic approach, remains underutilized in Japan compared to laparoscopic radical nephrectomy (LRN). In this study, we examined the safety and efficacy of laparoscopic partial nephrectomy (LPN) for T1a RCC compared to LRN. We also assessed the factors that affect the decision to perform LPN or LRN. (Patients and methods) From March 2001 to September 2014, 112 patients with T1a renal tumors received renal surgery at our institution. Of these, 100 patients (LPN: 36 patients, LRN: 64 patients) underwent laparoscopic surgery. Treatment outcomes including surgical and oncological outcomes among each approach were compared. In addition, multivariate analysis was performed to reveal the factors that affect the decision on surgical approach. (Results) The ratio of patients more than 75 years old and the RENAL nephrometry score were higher in LRN group than those in LPN group. Operating time was longer but renal function was well preserved in LPN group. Importantly, blood loss, intraoperative and postoperative complication rate, and oncological outcome (recurrence-free survival and overall survival) were similar in both groups. Multivariate analysis revealed that age (≥75 years old), high RENAL nephrometry score, operation period (before 2011), and the absence of Endoscopic Surgical Skill Qualification (ESSQ) in surgeon were independent predictive factors that select LRN. (Conclusions) Our data suggests that LPN for T1a renal tumor could be performed safely and the decision whether LPN or LRN were performed were associated with technical factors such as the presence of ESSQ or operation period, as well as patient's factor such as age and tumor factor such as tumor complexity.

Improvement of prognosis in patients with metastatic renal cell carcinoma and Memorial Sloan-Kettering Cancer Center intermediate risk features by modern strategy including molecular-targeted therapy in clinical practice.

OBJECTIVES: To identify the patient subgroups benefitting the most from the modern strategy including molecular-targeted therapy among patients with metastatic renal cell carcinoma (mRCC) in clinical practice. METHODS: Retrospective analysis of 144 patients with mRCC diagnosed between 1992 and 2011 at Kyoto University Hospital was conducted. Multivariate analysis using the Cox proportional hazards model was conducted to identify prognostic factors associated with overall survival (OS). Subgroup analysis was conducted to identify patients who benefitted the most from molecular-targeted therapy. RESULTS: Independent factors associated with worse OS are: tumors of histological type other than clear-cell, decreased hemoglobin (Hb), elevated lactate dehydrogenase (LDH), elevated C-reactive protein (CRP), and metastases at ≥ 3 sites. Median OS of patients treated with molecular-targeted therapy alone or with prior immunotherapy and those treated with immunotherapy alone was 57, 45 and 28 months, respectively. Molecular-targeted therapy had more effect on OS than immunotherapy alone among female patients, patients with Memorial Sloan-Kettering Cancer Center (MSKCC) intermediate risk features, and patients with metastatic progression less than 1 year after initial diagnosis of RCC, compared with their counterparts. CONCLUSIONS: The modern strategy including molecular-targeted therapy may improve OS in patients with mRCC and MSKCC intermediate risk features in clinical practice, relative to those with other risk features. However, the prognosis for patients with tumors of histological type other than clear-cell, decreased Hb, elevated LDH, elevated CRP, or metastases at ≥ 3 sites remains poor even in the modern molecular-targeted era. Novel treatment strategies are necessary to improve prognosis in these patients.

Safety and efficacy of ureteroscopy after obstructive pyelonephritis treatment.

OBJECTIVES: An obstructed, infected kidney combined with ureteral stones can be lethal, and requires urgent drainage and complete stone removal. However, the optimal method of stone removal, and its safety and efficacy have yet to be conclusively established. The aim of this study was to determine the safety and efficacy of carrying out ureteroscopy after kidney drainage for septic patients with obstructing stones. METHODS: From January 2004 to September 2011, 88 patients underwent stone removal by either ureteroscopy (n = 48) or extracorporeal shock wave lithotripsy (n = 40) after drainage of obstructive pyelonephritis. Patients' characteristics were analyzed, and treatment outcomes between the ureteroscopy and extracorporeal shock wave lithotripsy groups were compared. The outcomes of ureteroscopy carried out during the same period between patients with preoperative obstructive pyelonephritis and those without were also compared. RESULTS: Obstructed, infected kidneys were decompressed with retrograde ureteral stenting, except for two and three cases treated with nephrostomy in the ureteroscopy and extracorporeal shock wave lithotripsy groups, respectively. The severity of preoperative pyelonephritis was similar in both groups. Importantly, the success rate was 67.5% for extracorporeal shock wave lithotripsy and 98% for ureteroscopy (P < 0.001). Likewise, the retreatment and auxiliary procedure rates were significantly greater in the extracorporeal shock wave lithotripsy group than in the ureteroscopy group (90% vs 0% and 32.5% vs 2%, respectively). Furthermore, patients treated by ureteroscopy with or without preoperative pyelonephritis had similar stone-free and ureteroscopy complication rates (97% vs 93%, and 10% vs 12%). CONCLUSIONS: Ureteroscopy after drainage of an obstructed infected kidney can be a safe and effective option, as it seems to not be associated with an increased risk of complications.

[Treatment outcome of laparoscopic radical cystectomy at a single institution].

OBJECTIVE: The standard care for invasive bladder cancer is radical cystectomy with urinary diversion, but laparoscopic radical cystectomy (LRC) is still being evaluated. We describe our initial experience of laparoscopic radical cystectomy compared to open radical cystectomy (ORC). PATIENTS AND METHODS: From January 2000 to June 2012, 84 patients underwent radical cystectomy by ORC (n = 54) or LRC (n = 30). Treatment outcomes including surgical and oncological outcomes between LRC and ORC were compared. We also assessed learning curve during LRC as to blood loss, operating time and complication rate. RESULTS: The patients' characteristics were similar in LRC and ORC groups except for ASA score. Importantly, Operating time during LRC was longer but complication rate of LRC was lower than that of ORC (586 min vs 424 min and 40% vs 69%, respectively). In addition, pathological stage or outcomes were similar in both groups and there were no significant difference between LRC and ORC groups in terms of overall and recurrence free survival rate. As for learning curve of LRC, operating time and blood loss tended to decrease with increased experience. CONCLUSION: These results indicate that LRC could be performed safely with decreased complication rate and similar oncological outcomes compared to ORC.

Extracellular vesicles secreted from bone metastatic renal cell carcinoma promote angiogenesis and endothelial gap formation in bone marrow in a time-dependent manner in a preclinical mouse model.

Introduction: Bone is a major metastatic site of renal cell carcinoma (RCC). Recently, it is well recognized that bone metastatic tumor cells remodel bone marrow vasculature. However, the precise mechanism underlying cell-cell communication between bone metastatic RCC and the cells in bone marrow remains unknown. Extracellular vesicles (EVs) reportedly play crucial roles in intercellular communication between metastatic tumor cells and bone marrow. Therefore, we conducted the current study to clarify the histological alteration in vascular endothelium in bone marrow induced by EVs secreted from bone metastatic RCC cells as well as association between angiogenesis in bone marrow and bone metastasis formation. Materials and methods: We established a bone metastatic RCC cell line (786-O BM) by in vivo selection and observed phenotypic changes in tissues when EVs were intravenously injected into immunodeficient mice. Proteomic analysis was performed to identify the protein cargo of EVs that could contribute to histological changes in bone. Tissue exudative EVs (Te-EVs) from cancer tissues of patients with bone metastatic RCC (BM-EV) and those with locally advanced disease (LA-EV) were compared for in vitro function and protein cargo. Results: Treatment of mice with EVs from 786-O BM promoted angiogenesis in the bone marrow in a time-dependent manner and increased the gaps of capillary endothelium. 786-O BM EVs also promoted tube formation in vitro. Proteomic analysis of EVs identified aminopeptidase N (APN) as a candidate protein that enhances angiogenesis. APN knockdown in 786-O BM resulted in reduced angiogenesis in vitro and in vivo. When parental 786-O cells were intracardially injected 12 weeks after treatment with786-O BM EVs, more bone metastasis developed compared to those treated with EVs from parental 786-O cells. In patient samples, BM-EVs contained higher APN compared to LA-EV. In addition, BM-EVs promoted tube formation in vitro compared to LA-EVs. Conclusion: EVs from bone metastatic RCC promote angiogenesis and gap formation in capillary endothelium in bone marrow in a time-dependent manner.

[Outcome analysis of the urethral stent (Memotherm®)].

A number of patients with benign prostatic hyperplasia can not undergo surgical therapy because of advanced age, concomitant diseases, and other reasons. Since 1980, various types of urethral stents have been used for high-risk patients with benign prostatic hyperplasia. We report our experience with the use of urethral stents (Memotherm®). Between July 2002 and December 2010, we implanted urethral stents in 36 patients. The average follow-up period was 24.0 months. After stent implantation, 34 of the 36 patients were able to micturate. The average residual urine volume was 24.7 ml (0-250 ml), and the maximal urinary flow rate was 10.7 ml/s (3-24 ml/s). One stent had to be removed due to bladder tamponade, and one had to be exchanged due to dislocation. In 2 patients, a stone formed at the bladder end of the stent, and one of these patients underwent transurethral lithotripsy. Our results suggest that therapy with the Memotherm® urethral stent is a good option for patients suffering from urinary retention due to benign prostatic hyperplasia.

[Retrospective analysis of the long-term indwelling ureteral stent].

An indwelling ureteral stent is commonly used for relief of ureteral obstruction. However, few reports have documented the frequency of febrile urinary tract infection and changes in renal function in patients with long-term ureteral stent placement. Here we report our experience with patients who had undergone long-term placement of ureteral stents. Between January 2005 and March 2011, we performed exchange of ureteral stents in 25 patients for more than one year. The mean serum creatinine level at the baseline, after stent placement, and 1 year later was 2.10, 1.24, and 1.39 mg/dl, respectively. In 14 of the patients, 39 episodes of febrile urinary tract infection occurred. Among a total of 1,055 stent exchanges, 39 episodes (3.7%) of stent encrustation occurred. Two patients in whom stents had been forgotten suffered septic shock. The serum creatinine level following a long placement period did not change significantly, and of the patients whose hydronephrosis remained after stent placement, the risk of febrile urinary tract infection rises. Our results suggest that ureteral stents could be indwelt for a fairly long period of time without major complications as long as they were carefully followed up and regularly exchanged.