A case of adrenal cavernous hemangioma resected due to tumor growth accompanied by intratumoral hemorrhage.

Introduction: We describe a case of an adrenal cavernous hemangioma that was surgically resected because of tumor growth and intratumoral hemorrhage. Case presentation: A 73-year-old woman presented with an enlarged adrenal tumor and intratumoral hemorrhage during the follow-up of an incidental adrenal tumor. A computed tomography showed that the left adrenal tumor had grown from 23 to 44 mm over 1 year. Blood tests revealed a normal metabolic profile. Paragangliomas and metastatic tumors were suspected on imaging. Laparoscopic adrenalectomy was performed to prevent tumor rupture due to further bleeding. No adhesions or bleeding were observed around the tumor during surgery. Pathological diagnosis was adrenal cavernous hemangioma. Conclusion: Adrenal cavernous hemangioma is difficult to distinguish preoperatively from other adrenal tumors, including malignant tumors. The intraoperative findings of this case suggest that laparoscopic adrenalectomy is a safe treatment option for relatively small adrenal cavernous hemangioma.

Urethral caruncle causes acute urinary retention.

Introduction: We encountered a case of urinary retention caused by a urethral caruncle. Case presentation: An 86-year-old woman presented to our hospital with urinary retention. When the urinary bladder catheter was placed, a smooth, well-defined mass 20 mm in diameter was detected on the posterior wall of the external urethral meatus. The patient was diagnosed with urinary retention due to a urethral caruncle, and the mass was resected. The mass was pathologically compatible with a urethral caruncle. The patient could urinate postoperatively. Ultrasound test after surgery showed residual urine volume was 100 mL. Conclusion: Inspecting the urethral meatus is vital in the clinical examination of older women with voiding symptoms. A urethral caruncle is a rare cause of urinary retention. However, large urethral caruncles are at risk of causing urinary retention suggesting that resecting the urethral caruncles at an appropriate time is desirable.

Preoperative Risk Factor Analysis of Prolonged Retroperitoneoscopic Radical Nephrectomy.

BACKGROUND: This study aimed to investigate the preoperative risk factors for prolonged operating time in retroperitoneoscopic radical nephrectomy (RRN) for renal cell carcinoma (RCC). METHODS: We retrospectively reviewed patients treated for RRN between January 2015 and December 2021. Clinical data, including radiological findings such as visceral fat area (VFA), subcutaneous fat area (SFA), and posterior perirenal fat thickness (PFT) were collected. The operating time for RRN was analyzed using univariate and multivariate logistic regression analyses. RESULTS: A total of 79 patients were included. The median age was 66 (range: 28-88) years and 48 (60.8%) had right-sided tumors. The median tumor size was 52 (range: 12-100) mm. Median BMI, VFA, SFA, and posterior PFT were 22.9 (range: 16.3-42.2) kg/m2, 102 (range: 14-290) cm2, 124 (range: 33-530) cm2, and 6 (range: 1-35) mm. The median operating time was 248 (range: 140-458) min. Univariate logistic regression analyses revealed that a right tumor (p=0.046), tumor size >7 cm (p=0.010), and posterior PFT >25 mm (p=0.006) were preoperative risk factors for prolonged operating time in RRN. Multivariate logistic regression analyses revealed that a posterior PFT of >25 mm was an independent preoperative risk factor for prolonged operating time for RRN (p=0.008, OR: 7.29, 95% CI: 1.69-31.5). CONCLUSIONS: A posterior PFT >25 mm was an independent preoperative risk factor for the operating time of RRN. In RRN, for patients with a posterior PFT >25 mm, surgeons should develop surgical strategies, including the selection of a transperitoneal approach to surgery, to avoid prolonging the operating time.

A Case of a Huge Iliopsoas Abscess that Perforated and Communicated with the Ureter.

We experienced a rare case in which iliopsoas abscess (IPA), caused by an Extended Spectrum ß-Lactamase (ESBL)-producing Proteus mirabilis, perforated and communicated with the ureter and caused sepsis. An 84-year-old woman, bedridden due to sequelae of a cerebral hemorrhage, was brought to our hospital with a chief complaint of fever lasting for 3 weeks. Computed tomography (CT) revealed a huge 180 × 110 × 100 mm IPA in the right iliopsoas muscle. The ureter was also found to communicate with the iliopsoas muscle abscess, ureteral stenosis was detected at the same site, and dilatation of the renal pelvis occurred above the area of the ureteral stenosis, indicating hydronephrosis. Considering the mechanism of this case, if the ureter first ruptures and urine leaks, followed by the formation of an IPA, urine will flow along the surrounding fatty tissue and cause an abscess around the ureter and kidney. However, because almost no abscess was detected around the ureter, the abscess was thought to have originated from the iliopsoas muscle located near the center of the ureter. In summary, in this case, an abscess first formed within the iliopsoas muscle, which gradually expanded and compressed the right ureter, resulting in hydronephrosis. The upper ureter, which had become dilated and thinned due to ureteral obstruction, became even more fragile because of the spread of inflammation from the IPA, and the IPA perforated and communicated with the ureter. In patients who have difficulty communicating, the diagnosis of IPA may be delayed because the only symptom is fever. As in this case, if the diagnosis is delayed, the abscess may become large and perforate the ureter; thus, IPA should always be considered as a cause of fever of unknown origin.

Difficulty in Removing a Ureteral Stent post Childbirth due to Encrustation: A Case Report.

BACKGROUND: We present a case involving a pregnant woman who needed transurethral lithotripsy for ureteral stent removal because of the stent encrustation. CLINICAL CASE: A 34-year-old woman was diagnosed with calculous pyelonephritis, and a double-loop ureteral stent was placed in her right ureter, after which the pyelonephritis resolved. One week after her delivery, we attempted to remove the ureteral stent; however, the encrustation of the proximal and distal coils made it impossible. We then crushed the encrustation by transurethral lithotripsy and removed the ureteral stent successfully. The encrustation component was calcium phosphate, and the urinary pH during pregnancy and after delivery was 7.5. CONCLUSION: Even in pregnant patients, patients placed ureteral stents for obstructive pyelonephritis with high urine pH might need to be replaced in the short term due to concerns regarding phosphate encrustation.

Preoperative analysis of factors associated with prolonged pneumoretroperitoneum time during retroperitoneal laparoscopic nephroureterectomy for upper tract urothelial carcinoma.

BACKGROUND: Prolonged laparoscopic nephroureterectomy (LNU) for upper tract urothelial cancer (UTUC) can increase the frequency of intravesical recurrence after surgery. Therefore, it is important for urological surgeons to have knowledge on preoperative risk factors for prolonged LNU. However, few studies have investigated the risk factors for prolonged LNU. We hypothesized that the quantity of perirenal fat affects the pneumoretroperitoneum time (PRT) of retroperitoneal LNU (rLNU). This study aimed to investigate the preoperative risk factors for prolonged PRT during rLNU. METHODS: We reviewed the data of 115 patients who underwent rLNU for UTUC between 2013 and 2021. The perirenal fat thickness (PFT) observed on preoperative computed tomography (CT) images was used to evaluate the perinephric fat quantity. Preoperative risk factors for PRT during rLNU were analyzed using logistic regression models. The cutoff value for PRT was determined based on the median time.The cutoff values for fat-related factors influencing PRT were defined according to receiver operating characteristic curve analysis. RESULTS: The median PRT for rLNU was 182 min (interquartile range, 155-230 min). The cutoff values of posterior, lateral, and anterior PFTs were 15 mm, 24 mm, and 6 mm, respectively. Multivariate analysis revealed that a posterior PFT ≥ 15 mm (odds ratio [OR], 2.72; 95% confidence interval, 1.04-7.08; p = 0.0410) was an independent risk factor for prolonged PRT. CONCLUSIONS: Thick posterior PFT is a preoperative risk factor for prolonged PRT during rLNU. For patients with UTUC and thick posterior PFT, surgeons should develop optimal surgical strategies, including the selecting an expert surgeon as a primary surgeon and the selecting transperitoneal approach to surgery or open surgery.

Preoperative oral treatment with cyclooxygenase-2 inhibitor for cystitis glandularis.

Introduction: A previous report has shown that cyclooxygenase-2 inhibitors can prevent the recurrence of cystitis glandularis postoperatively. Herein, we present a case of cystitis glandularis in which the tumor volume was markedly reduced by preoperative oral administration of a cyclooxygenase-2 inhibitor. Case presentation: A 45-year-old man with voiding difficulty and lower abdominal pain during urination was referred to our hospital. Cystoscopy revealed multiple cystitis glandularis-like edematous masses on the trigone and the neck of the bladder, completely involving the bilateral ureteral orifices. Cyclooxygenase-2 inhibitor was orally administered at the patient's request. Six weeks later, the tumor volume was markedly reduced, bilateral ureteral orifices were identified, and the voiding difficulty and pain on urination disappeared. Complete transurethral resection of the residual tumor was performed, and the pathological diagnosis was intestinal-type cystitis glandularis. Conclusion: Cyclooxygenase-2 inhibition can be considered a useful therapeutic strategy for cystitis glandularis.

Usefulness of hand-assisted retroperitoneal laparoscopic radical nephrectomy for extreme obese patients -a case report.

We report a case of retroperitoneal laparoscopic radical nephrectomy (LRN) in which the addition of a hand port was necessary and effective. A 52-year-old man with obesity (BMI 40.6 kg/m2) was diagnosed with a 52-mm left renal cell carcinoma (cT1bN0M0). To avoid thick subcutaneous and visceral fat in the abdomen, we selected LRN using a retroperitoneal approach with four ports in the kidney position. During surgery, a large amount of flank pad and perirenal fat prevented us from securing a sufficient surgical field through traction of the kidney with a retractor. A pure laparoscopic procedure was not feasible;therefore, we added a hand port. Subsequently, we removed the flank pad from the hand port and secured the surgical field by tracing the kidney manually. Finally, hand-assisted LRN was completed without an open conversion. In retroperitoneal LRN, we rarely encounter patients for whom a pure laparoscopic procedure is not feasible because of the large amount of flank pad or perirenal fat. It is important to preoperatively confirm not only the BMI but also the amount of flank pad and perirenal fat on imaging. Hand-assisted LRN via the retroperitoneal approach can be safely performed even in extremely obese patients. J. Med. Invest. 71 : 187-190, February, 2024.

Index tumor location affected early biochemical recurrence after radical prostatectomy in patients with negative surgical margin: a retrospective study.

BACKGROUND: Index tumors are the most aggressive tumors of the prostate. However, their clinical significance remains unclear. This study aimed to assess the incidence of index tumor location according to the zonal origin and whether these locations affect the prognosis after radical prostatectomy in patients with negative surgical margins. METHODS: This single-centered, retrospective study evaluated 1,109 consecutive patients who underwent radical prostatectomies. An index tumor was defined as the largest tumor in the prostate gland. We detected these locations based on McNeal's zonal origin using whole-mount sections. Biochemical recurrence (BCR) free survival curves were generated using the Kaplan-Meier method. Univariate and multivariate analyses using the Cox proportional hazards model were performed to determine the predictive factors for early BCR (within 1-year). RESULTS: A total of 621 patients with negative surgical margins who did not receive adjuvant therapy were included in this study. The index tumor were located in the transitional zone in 191 patients (30.8%), the peripheral zone in 399 patients (64.3%), and the central zone in 31 patients (5.0%). In total, 22 of 621 patients (3.5%) experienced early BCR and 70 patients (11.2%) experienced overall BCR at a median follow-up of 61.7 months. According to the index tumor location, the early BCR-free rates were 99.5%, 95.7 %, and 83.3% in the transitional, peripheral, and central zones, respectively. On multivariate analysis, the index tumor in the central zone was an independent predictor of early BCR with negative surgical margins following radical prostatectomy, followed by prostatectomy pathological grade, index tumor in the peripheral zone, and high prostate-specific antigen level. CONCLUSIONS: We assessed the significance of index tumor location in patients with negative surgical margins following radical prostatectomy. Index tumors located in the central zone, although infrequent, were the strongest predictive factors for early BCR. Our results may allow urologists and patients to reconsider the therapeutic strategies for prostate cancer.

Preoperative rapid growth of inferior vena cava tumor thrombus in renal cell carcinoma.

Introduction: We present the case of a rapidly growing inferior vena cava tumor thrombus in renal cell carcinoma. Case presentation: We present a case of a 66-year-old woman with right renal cell carcinoma with a tumor thrombus extending 2 cm into the inferior vena cava on an initial Imaging. Radical surgery was performed 6 weeks after the first visit. Intraoperatively, the tumor thrombus was confirmed to have grown near the diaphragm. The tumor was resected using an inferior vena cava clamping just below the diaphragm. The tumor thrombus and renal cell carcinoma were completely removed. There was no recurrence 6 months postoperatively. Conclusion: Inferior vena cava tumor thrombus in renal cell carcinoma can grow in a short period, suggesting that preoperative imaging evaluation at the appropriate time is important. Once inferior vena cava tumor thrombus of renal cell carcinoma occurs, surgery should not be delayed unless there is an urgent reason.

Analysis of bacteremia at first-line antibiotic treatment for febrile neutropenia in children and adolescents: A retrospective, single-center analysis.

BACKGROUND: Control of bacterial and fungal infections is critical to improving outcomes in hematological neoplastic diseases of children and adolescents. In this study, a retrospective analysis of our previous studies on febrile neutropenia was performed to investigate bacteremia. PROCEDURE: From August 2008 to December 2023, five antibiotic studies were performed for febrile and neutropenic pediatric patients who had been treated with chemotherapy, immunosuppressive therapy, or had received stem cell transplantation in the pediatric unit at Sapporo Hokuyu Hospital. The rate of positive blood culture, detected bacteria, and susceptibility of several types of antibiotics in febrile episodes were investigated. RESULTS: Blood culture was positive in 133 of 1604 febrile episodes of 329 patients. Detected bacteria were Gram-positive cocci (61.2 %), Gram-negative bacilli (27.6 %), Gram-negative cocci (0.7 %), and Gram-positive bacilli (10.4 %). The incidence of bacteremia over time showed a decreasing trend with each passing year. In particular, the incidence of bacteremia was around 10 % in 2008-2013, whereas it was often below 5 % after 2020; this decrease was statistically significant. Although almost all detected bacteria and their susceptibilities to antibiotics (piperacillin/tazobactam, meropenem, ceftazidime, and cefozopran) did not change over time, all Escherichia coli detected after 2014 were extended-spectrum ß-lactamase-producing bacteria.

Real-World Insights into Efficacy and Safety of Enfortumab Vedotin in Japanese Patients with Metastatic Urothelial Carcinoma: Findings, Considerations, and Future Directions.

This study presents the enfortumab vedotin (EV) treatment analysis at our institution. We retrospectively analyzed patients with metastatic urothelial cancer (mUC) treated with EV between January 2021 and October 2023. EV was administered at 1.25 mg/kg on days 1, 8, and 15 in a 28-day cycle. Whole-body computed tomography scans were performed to assess the treatment response. Patient characteristics, treatment histories, response rates, progression-free survival, and adverse events were evaluated. Response rates were determined, and adverse events were recorded. Among the 20 patients, 70% were male and 65% had bladder tumors. Most patients had lung (65%) or lymph node (65%) metastases. The median follow-up was 11.2 months, with 45% of the patients succumbing to the disease. The overall response rate was 55%. The median progression-free and median overall survivals were 10.5 and 12.9 months, respectively. Severe adverse events occurred in 35% of patients. In this real-world study, EV demonstrated promising efficacy and manageable safety profiles in Japanese patients with mUC. The study's results were consistent with previous clinical trials, although a longer follow-up was required. Our findings support EV use as a treatment option for patients with mUC who exhibit disease progression after platinum-based chemotherapy and immune-checkpoint inhibitor therapy.

Nelarabine-containing salvage therapy and conditioning regimen in transplants for pediatric T-cell acute lymphoblastic leukemia and lymphoma.

Therapy for relapsed or refractory (r/r) T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) in children is challenging, and new treatment methods are needed. We retrospectively analyzed eight patients with r/r T-ALL (five patients) and T-LBL (three patients) who were treated with nelarabine (NEL) plus etoposide, cyclophosphamide, and intrathecal therapy, administered 3 days apart. Five patients achieved a complete response, and the other three achieved a partial response (PR). All patients underwent hematopoietic stem cell transplantation (HSCT) after two cycles of treatment, except for one patient who received one cycle. Three patients who had previously received HSCT were treated with reduced-intensity conditioning regimens, including fludarabine, melphalan, and NEL; one survived for over 5 years after the second HSCT. Grade 2 neuropathy occurred in one patient, but other severe toxicities commonly associated with NEL were not observed during NEL administration in combination with chemotherapy. The 2-year overall survival and event-free survival rates were 60.0% and 36.5%, respectively. The addition of NEL to reinduction chemotherapy was useful in achieving remission and did not lead to excessive toxicity. In addition, a conditioning regimen, including NEL, appeared to be effective in patients who had previously undergone HSCT.

Obstructive azoospermia caused by epididymis injury with testicle rupture on the other side.

Background: Epididymal injuries without ipsilateral injuries of the testicles are rare. We report a case of a solitary right epididymal injury complicated by left testicular rupture. Case Presentation: A 21-year-old man experienced scrotal trauma caused by a motorcycle accident. Bilateral swelling and tenderness of the scrotum were observed. Ultrasonography and computed tomography revealed a ruptured left testicle; therefore, surgery was performed. During surgery, the left testicle was excised because it was completely ruptured, and the right testicle and epididymis were evaluated to identify the cause of swelling of the right scrotum. The right testis was not injured; however, the right epididymis was lacerated. Subsequently, the lacerated right epididymis was repaired using sutures. A semen analysis performed at 1, 4, and 7 months after surgery revealed the absence of sperm in the semen. Conclusion: Epididymal injuries should be considered as differential diagnoses for scrotal trauma.

Analysis of non-alcoholic fatty liver disease during induction therapy for B-cell precursor acute lymphoblastic leukemia in children and adolescents.

BACKGROUND: A prospective evaluation of non-alcoholic fatty liver disease (NAFLD) during induction therapy for acute lymphoblastic leukemia (ALL) has not been performed. Herein, we prospectively investigated the frequency, risk factors, and outcomes of NAFLD during induction therapy in children and adolescents with B-cell precursor ALL (BCP-ALL). METHODS: This study enrolled 74 newly diagnosed BCP-ALL cases aged 1 year and older who were admitted to our department between January 2011 and December 2020. Median age was 6.6 years (1.3-17.5 years). Plain computed tomography (CT) of the upper abdomen was performed before induction therapy, and on days 15 and 29 after initiation of induction therapy. Patients with a liver/spleen CT ratio <0.9 were defined as having NAFLD. RESULTS: The frequency of NAFLD was 73%. Patients with NAFLD had a higher rate of hypertriglyceridemia. There was no significant difference in 5-year overall survival and event-free survival (EFS) between patients with and without NAFLD. However, after restricting the target age to 10 years and older, 5-year EFS was significantly higher in patients with NAFLD than in those without (88.5 vs. 42.9%, respectively, P = 0.037). Similarly, 5-year cumulative incidence of relapse (CIR) was significantly lower in patients with NAFLD than in those without it (5-year CIR, 6.3 vs. 57.1%, respectively, P = 0.013). CONCLUSION: Patients with NAFLD exhibit better outcomes including 5-year EFS and CIR. Further studies are necessary.

The Japanese Urological Association's clinical practice guidelines for urotrauma 2023.

The Japanese Urological Association's guidelines for the treatment of renal trauma were published in 2016. In conjunction with its revision, herein, we present the new guidelines for overall urotrauma. Its purpose is to provide standard diagnostic and treatment recommendations for urotrauma, including iatrogenic trauma, to preserve organ function and minimize complications and fatality. The guidelines committee comprised urologists with experience in urotrauma care, selected by the Trauma and Emergency Medicine Subcommittee of the Specialty Area Committee of the Japanese Urological Association, and specialists recommended by the Japanese Association for the Surgery of Trauma and the Japanese Society of Interventional Radiology. The guidelines committee established the domains of renal and ureteral, bladder, urethral, and genital trauma, and determined the lead person for each domain. A total of 30 clinical questions (CQs) were established for all domains; 15 for renal and ureteral trauma and five each for the other domains. An extensive literature search was conducted for studies published between January 1, 1983 and July 16, 2020, based on the preset keywords for each CQ. Since only few randomized controlled trials or meta-analyses were found on urotrauma clinical practice, conducting a systematic review and summarizing the evidence proved challenging; hence, the grade of recommendation was determined according to the 2007 "Minds Handbook for Clinical Practice Guidelines" based on a consensus reached by the guidelines committee. We hope that these guidelines will be useful for clinicians in their daily practice, especially those involved in urotrauma care.

A case of renal abscess mimicking metastatic lesion in a patient with lung carcinosarcoma.

Renal abscesses require prompt diagnosis and appropriate intervention, as they can be life-threatening. However, diagnosis based solely on clinical findings is often challenging. We present the case of a 69-year-old woman with left renal masses on follow-up computed tomography (CT) after surgery for pT2aN0M0 lung carcinosarcoma. The masses were localized only in the left kidney without suspected metastatic lesions at other sites. The patient was referred to our department for further evaluation and treatment under a diagnosis of suspected metastatic lung carcinosarcoma of the left kidney. On enhanced CT, the left renal masses, the largest of which had a diameter of 40×36 mm had thick irregular walls gradually enhanced by the contrast media and an internal low-attenuation area. The masses showed heterogeneous signal intensity with a pseudocapsule on T2-weighted magnetic resonance imaging. Clinical symptoms such as fever or costovertebral angle tenderness were absent, and blood and urine tests were not sufficiently inflammatory to suggest a renal abscess. Histopathological findings on CT-guided renal biopsy revealed only inflammatory tissue and no tumor cells. However, because lung carcinosarcoma metastatic nodules could not be ruled out, laparoscopic left nephrectomy was performed for a definitive diagnosis and curative intent. The pathological diagnosis was renal abscess without malignant lesions. Here, we present a case of renal abscess mimicking metastatic lesions in a patient with lung carcinosarcoma. Accurately differentiating renal abscesses from metastatic renal tumors before treatment is often difficult. Renal abscess diagnosis should be considered through a comprehensive evaluation of the clinical findings of individual cases.

A case of marked rectal stenosis due to Douglas' pouch metastasis of renal pelvic carcinoma successfully treated with salvage enfortumab vedotin: correlation between serum KL-6 levels and tumor response.

Introduction: We report a rare case of marked rectal stenosis due to Douglas' pouch metastasis of renal pelvic urothelial carcinoma successfully treated with enfortumab vedotin. Case presentation: A 77-year-old female presented with difficulty in defecation and abdominal distension. She had received two courses of cisplatin plus gemcitabine followed by four courses of maintenance avelumab for postoperative lymph node metastasis of renal pelvic urothelial carcinoma. KL-6 levels were elevated, and a computed tomography scan revealed an irregularly shaped large mass occupying Douglas' pouch, with marked rectal stenosis. Metastatic urothelial carcinoma was pathologically diagnosed, and enfortumab vedotin was initiated after colostomy. After 12 courses of enfortumab vedotin, metastatic lesions showed marked shrinkage and KL-6 levels decreased. Conclusion: Enfortumab vedotin elicited a remarkable response in treating rectal stenosis due to metastasis of renal pelvic urothelial carcinoma in Douglas' pouch. Furthermore, serum KL-6 levels were correlated with the severity of metastatic urothelial carcinoma.

Primary leiomyoma of the bladder radiologically mimicking a retroperitoneal tumor - a case report.

The case presented is of a 47-year-old patient with an extravesical pedunculated bladder leiomyoma, which was difficult to distinguish from a retroperitoneal tumor. Preoperatively, it was suspected to be a retroperitoneal tumor and a laparotomy with tumor resection was performed. lntraoperatively, the bladder and tumor were connected by a cord-like tissue. A retrospective review of preoperative images revealed that cord-like tissue, identified intraoperatively, was also present. Bladder leiomyomas can grow as extravesical pedunculated tumors. Therefore, when the continuity between the bladder and tumor is only a cord-like object, the finding ofcontinuity is useful to diagnose with bladder leiomyoma. J. Med. Invest. 70 : 513-515, August, 2023.

Perirenal fat stranding as a predictor of disease progression after radical nephroureterectomy for renal pelvic urothelial carcinoma: a retrospective study.

BACKGROUND: To investigate the impact of Perirenal fat stranding (PRFS) on progression after radical nephroureterectomy (RNU) for renal pelvic urothelial carcinoma (RPUC) without hydronephrosis and to reveal the pathological findings of PRFS. METHODS: Clinicopathological data, including computed tomography (CT) findings of the ipsilateral PRFS, were collected from the medical records of 56 patients treated with RNU for RPUC without hydronephrosis between 2011 and 2021 at our institution. PRFS on CT was classified as either low or high PRFS. The impact of PRFS on progression-free survival (PFS) after RNU was analyzed using the Kaplan-Meier method and log-rank test. In addition, specimens including sufficient perirenal fat from patients with low and with high PRFS were pathologically analyzed. Immunohistochemical analysis of CD68, CD163, CD3, and CD20 was also performed. RESULTS: Of the 56 patients, 31(55.4%) and 25 (44.6%) patients were classified as having low and high PRFS, respectively. Within a median follow-up of 40.6 months postoperatively, 11 (19.6%) patients showed disease progression. The Kaplan-Meier method and log-rank test revealed that patients with high PRFS had significantly lower PFS rates than those with low PRFS (3-year PFS 69.8% vs 93.3%; p = 0.0393). Pathological analysis revealed that high PRFS specimens (n = 3 patients) contained more fibrous strictures in perirenal fat than low PRFS specimens (n = 3 patients). In addition, M2 macrophages (CD163 +) infiltrating fibrous tissue in perirenal area were observed in all patients with high PRFS group. CONCLUSIONS: PRFS of RPUC without hydronephrosis consists of collagenous fibers with M2 macrophages. The presence of ipsilateral high PRFS might be a preoperative risk factor for progression after RNU for RPUC patients without hydronephrosis. Prospective studies with large cohorts are required in the future.