Tumor-infiltrating CD8+ T cells recognize a heterogeneously expressed functional neoantigen in clear cell renal cell carcinoma.

Immune checkpoint inhibitors (ICIs) are used in cancer immunotherapy to block programmed death-1 and cytotoxic T-lymphocyte antigen 4, but the response rate for ICIs is still low and tumor cell heterogeneity is considered to be responsible for resistance to immunotherapy. Tumor-infiltrating lymphocytes (TILs) have an essential role in the anti-tumor effect of cancer immunotherapy; however, the specificity of TILs in renal cell carcinoma (RCC) is elusive. In this study, we analyzed a 58-year-old case with clear cell RCC (ccRCC) with the tumor showing macroscopic and microscopic heterogeneity. The tumor was composed of low-grade and high-grade ccRCC. A tumor cell line (1226 RCC cells) and TILs were isolated from the high-grade ccRCC lesion, and a TIL clone recognized a novel neoantigen peptide (YVVPGSPCL) encoded by a missense mutation of the tensin 1 (TNS1) gene in a human leukocyte antigen-C*03:03-restricted fashion. The TNS1 gene mutation was not detected in the low-grade ccRCC lesion and the TIL clone did not recognized low-grade ccRCC cells. The missense mutation of TNS1 encoding the S1309Y mutation was found to be related to cell migration by gene over-expression. These findings suggest that macroscopically and microscopically heterogenous tumors might show heterogenous gene mutations and reactivity to TILs.

Neuregulin-1-ß1 and γ-secretase play a critical role in sphere-formation and cell survival of urothelial carcinoma cancer stem-like cells.

Previously, we investigated gene expression in a high aldehyde dehydrogenase 1 expression (ALDH1high) population of urothelial carcinoma (UC) cells as UC cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) and found that NRG1 expression was upregulated in ALDH1high cells. NRG1 is a trophic factor that contains an epidermal growth factor (EGF)-like domain that signals by stimulating ERBB receptor tyrosine kinases and the cytoplasmic domain. NRG1 has been determined to be involved in frequent gene fusions with other partners in several malignancies and has a role in carcinogenesis through the NRG1 EGF-like domain and its cognitive receptor ERBBs. We thus aimed to elucidate the function of NRG1 in UC CSCs/CICs in this study. Both NRG1α and NRG1-ß1 were preferentially expressed in ALDH1high cells compared with ALDH1low cells; however, siRNA experiments revealed that NRG1-ß1 but not NRG1-α has a role in sphere formation. The EGF-like domain of NRG1 had a role in sphere formation of UC cells to some extent but was not essential. The intracellular domain of NRG1 did not have a role in sphere-formation. Inhibition of γ-secretase suppressed sphere formation. These findings indicate that cleavage of NRG1-ß1 by γ-secretase plays an important role in UC CSC/CIC proliferation; however, the downstream targets of NRG1-ß1 remain elusive.

Antiresorptive agent-related osteonecrosis of the jaw (ARONJ) in urological malignancies: a multi-center retrospective study.

INTRODUCTION: We evaluated the incidence and risk factors for antiresorptive agent-related osteonecrosis of the jaw (ARONJ) in prostate and kidney cancer patients. MATERIALS AND METHODS: We retrospectively reviewed the clinical data of 547 patients from 13 hospitals. Prostate and kidney cancer patients with bone metastases who were treated with a bone-modifying agent (BMA) between January 2012 and February 2019 were enrolled. Exclusion criteria were BMA use for hypercalcemia, a lack of clinical data, a follow-up period of less than 28 days and a lack of evaluation by dentists before BMA administration. The diagnosis and staging of ARONJ were done by dentists. RESULTS: Two-hundred eighteen patients were finally enrolled in the study, including 168 prostate cancer patients and 50 kidney cancer patients. Of them, 49 (29%) prostate cancer patients and 18 (36%) kidney cancer patients needed tooth extraction prior to BMA initiation. The mean follow-up period after BMA initiation was 552.9 ± 424.7 days (mean ± SD). In the cohort, 23% of the patients were diagnosed with ARONJ in the follow-up period. The 1-year cumulative incidences of ARONJ were 9.4% and 15.4% in prostate and kidney cancer patients, respectively. Multivariate analysis indicated that kidney cancer, tooth extraction before BMA and a body mass index (BMI) ≥ 25 kg/m2 were significant predictors for ARONJ. CONCLUSION: ARONJ is not a rare adverse event in urological malignancies. Especially, kidney cancer, high BMI patients and who needed tooth extraction before BMA were high risk for developing ARONJ.

Does cognitive behavioral therapy using a self-check sheet improve night-time frequency in patients with nocturia? Results of a multicenter randomized controlled trial.

OBJECTIVE: To determine whether cognitive behavioral therapy using a self-check sheet is effective in improving night-time frequency of patients with nocturia. METHODS: We carried out a multicenter, open-labeled, randomized controlled trial in eight institutions. Patients having two or more episodes of nocturia were randomly assigned to either cognitive behavioral therapy with completion of frequency volume charts regularly (cognitive behavioral therapy group) or frequency volume charts regularly alone (frequency volume charts group). The cognitive behavioral therapy checklist was composed of eight items: wake up time/bedtime, mealtime, napping, alcohol/caffeine intake, water intake, salt intake, exercise and taking a bath. A physician explained cognitive behavioral therapy within 5 min using a brief manual. The patients in the cognitive behavioral therapy group filled out the self-check sheet every day. The primary end-point was the difference in night-time frequency based on the International Prostate Symptom Score Q7 at 4 weeks. RESULTS: Of the 100 first-visit patients randomly allocated, 37 in the cognitive behavioral therapy group and 41 in the frequency volume charts group completed the protocol. No difference was observed in the mean ± standard deviation of night-time frequency at 4 weeks between the cognitive behavioral therapy group (2.6 ± 1.0) and the frequency volume charts group (3.1 ± 1.2; P = 0.056). However, when six patients with achievement of cognitive behavioral therapy of <50% were excluded from the analysis, night-time frequency at 4 weeks was significantly lower in the cognitive behavioral therapy group (2.5 ± 1.0) than in the frequency volume charts group (3.1 ± 1.2; P = 0.027). CONCLUSIONS: The efficacy of cognitive behavioral therapy using a self-check sheet for nocturia remains to be shown. However, strictly practicing cognitive behavioral therapy might be beneficial to these patients.

The neutrophil-lymphocyte ratio has a role in predicting the effectiveness of nivolumab in Japanese patients with metastatic renal cell carcinoma: a multi-institutional retrospective study.

BACKGROUND: The neutrophil-lymphocyte ratio (NLR) is a well-known prognostic marker in various cancers. However, its role as a predictive marker for the effectiveness of nivolumab in patients with metastatic RCC (mRCC) remains unclear. We evaluated the relationships between the NLR and progression-free survival (PFS) or overall survival (OS) in mRCC patients treated with nivolumab. METHODS: The data of 52 mRCC patients who received nivolumab therapy were collected from seven institutes and evaluated. The median follow-up period from treatment with nivolumab was 25.2 months (IQR 15.5-33.2). RESULTS: The median duration of nivolumab therapy was 7.1 months (IQR 2.9-24.4). The objective response rate was 25% and the 1- and 2-year PFS rates were 46.2 and 25.2%, respectively. The median NLR values at baseline and 4 weeks were 3.7 (IQR 2.7-5.1) and 3.3 (IQR 2.4-5.7), respectively. In the multivariate analysis, an NLR of ≥3 at 4 weeks was an independent predictor of PFS (P = 0.013) and OS (P = 0.034). The 1-year PFS of patients with an NLR of < 3 at 4 weeks was better than that of those with an NLR of ≥3 (75% versus 29%, P = 0.011). The 1-year OS of patients with an NLR of < 3 at 4 weeks was also better than that of those with an NLR of ≥3 (95% versus 71%, P = 0.020). CONCLUSIONS: Although the baseline NLR was not associated with PFS or OS, an NLR of ≥3 at 4 weeks after the initiation of therapy might be a robust predictor of poor PFS and OS in mRCC patients undergoing sequential treatment with nivolumab.

Incidence and risk factors of postoperative delirium in elderly patients undergoing urological surgery: A multi-institutional prospective study.

OBJECTIVES: To investigate the incidence and risk factors of postoperative delirium among patients aged ≥65 years undergoing elective urological surgery. METHODS: From April 2015 through December 2016, 1023 consecutive patients aged ≥65 years who received transurethral, laparoscopic (with or without robot assistance) or open surgery in eight institutions were enrolled in this prospective observational study. Their preoperative cognitive status was assessed with the Hasegawa Dementia Scale-Revised score. The treating physician or nurse assessed delirium using the Intensive Care Delirium Screening Checklist. Multivariate logistic regression analysis was used to determine predictive factors for postoperative delirium. RESULTS: We analyzed 946 patients whose median age was 74 years (range 65-95 years). Postoperative delirium was observed in 32 patients (3.4%). Multivariate analysis showed that a history of cerebrovascular disease (odds ratio 5.24, 95% confidence interval 2.05-13.40), low Hasegawa Dementia Scale-Revised score <20 points (odds ratio 3.50, 95% confidence interval 1.36-9.02), low serum albumin level <3.5 g/dL (odds ratio 3.12, 95% confidence interval 1.25-7.83) and long surgery duration >4 h (odds ratio 4.94, 95% confidence interval 2.20-11.10) were independent risk factors for the development of postoperative delirium. CONCLUSIONS: The preoperative medical history, cognitive status, low serum albumin level and operative duration were associated with the development of postoperative delirium, although the incidence was just 3.4% in elective urological surgery. The present results suggest that the Hasegawa Dementia Scale-Revised is a useful tool for assessment of the risk for delirium.

Antitumor and Antiangiogenic Activities of Lenvatinib in Mouse Xenograft Models of Vascular Endothelial Growth Factor-Induced Hypervascular Human Hepatocellular Carcinoma.

High expression of vascular endothelial growth factor (VEGF) in patients with hepatocellular carcinoma (HCC) is associated with poor prognosis. Here, we investigated the antitumor activity of lenvatinib, a multiple receptor tyrosine kinase inhibitor, in VEGF-overexpressing HCC models. In human umbilical vein endothelial cells, lenvatinib showed potent inhibitory activities against VEGF-induced proliferation and VEGF/basic fibroblast growth factor-induced tube formation. In VEGF-overexpressing HCC xenograft models, characterized by aggressive tumor growth and hypervascularity, lenvatinib had significant antitumor and antiangiogenic activities. These results suggest that potent activity of lenvatinib against VEGF signaling underlies its antitumor and antiangiogenic activities in the hypervascular HCC models.

[PD-L1-Mediated Immune Escape Mechanism of Cancer Stem-Like Cells].

Immune checkpoint inhibitors(ICIs)have provided great success in cancer treatment field, and immunotherapies using ICIs have become standard therapy for several cancers. Cancer stem-like cells(CSCs)are defined by their higher tumorigenicity and resistance to chemotherapy and radiotherapy, thus they are supposed to be responsible for recurrence and distant metastasis. Therefore, control of CSCs is a key factor to improve patients' prognosis. In this review article, we summarize the expression of PD-L1, a molecular target of ICIs, in CSCs, and discuss the possibility of CSC-targeting immunotherapy using ICIs.

[Necrotizing Fasciitis and Frostbite of the Male External Genitalia : A Case Repor].

We report a case diagnosed as both necrotizing fasciitis and frostbite of the male external genetalia. The patient was a 58-year-old man with diabetes mellitus. He was referred to our hospital with swelling of his penis and icing there for 3 weeks. We diagnosed his condition as necrotizing fasciitis of the external genitalia and decided to perform an emergency operation. Although we consulted plastic surgeons about debridement of a large area, they considered that there was no necessity for it because the scrotum, perineum and abdominal wall were frostbitten. The final clinical diagnosis was necrotizing fasciitis of the penile region and frostbite around the perineal region. We performed partial penectomy without debridement. Through collaboration with another medical department it was thus possible to avoid unnecessary invasive treatment.

Targeting of tumor growth and angiogenesis underlies the enhanced antitumor activity of lenvatinib in combination with everolimus.

The combination of lenvatinib, a multiple receptor tyrosine kinase inhibitor, plus everolimus, a mammalian target of rapamycin (mTOR) inhibitor, significantly improved clinical outcomes versus everolimus monotherapy in a phase II clinical study of metastatic renal cell carcinoma (RCC). We investigated potential mechanisms underlying the antitumor activity of the combination treatment in preclinical RCC models. Lenvatinib plus everolimus showed greater antitumor activity than either monotherapy in three human RCC xenograft mouse models (A-498, Caki-1, and Caki-2). In particular, the combination led to tumor regression in the A-498 and Caki-1 models. In the A-498 model, everolimus showed antiproliferative activity, whereas lenvatinib showed anti-angiogenic effects. The anti-angiogenic activity was potentiated by the lenvatinib plus everolimus combination in Caki-1 xenografts, in which fibroblast growth factor (FGF)-driven angiogenesis may contribute to tumor growth. The combination showed mostly additive activity in vascular endothelial growth factor (VEGF)-activated, and synergistic activity against FGF-activated endothelial cells, in cell proliferation and tube formation assays, as well as strongly suppressed mTOR-S6K-S6 signaling. Enhanced antitumor activities of the combination versus each monotherapy were also observed in mice bearing human pancreatic KP-1 xenografts overexpressing VEGF or FGF. Our results indicated that simultaneous targeting of tumor cell growth and angiogenesis by lenvatinib plus everolimus resulted in enhanced antitumor activity. The enhanced inhibition of both VEGF and FGF signaling pathways by the combination underlies its superior anti-angiogenic activity in human RCC xenograft models.

The discrepancy between serum creatinine and cystatin C can predict renal function after treatment for postrenal acute kidney injury: multicenter study and pooled data analysis.

BACKGROUND: Although serum cystatin C and creatinine are used as practical markers of renal function, the discrepancy between them in postrenal acute kidney injury (AKI) cases was reported. The aim of this study was to determine whether the preoperative serum cystatin C (pre-CysC) level could predict clinical outcomes after treatment in patients with postrenal AKI. METHODS: Patients who underwent urological interventions with postrenal AKI were enrolled in this prospective observational study. Associations among preoperative serum creatinine (pre-sCr), pre-CysC, and nadir postoperative serum creatinine (post-sCr) were evaluated. In addition, based on our results in combination with detailed data from the literature, a predictive equation for postoperative serum creatinine (post-sCr) was developed by simple regression analysis and validated using Bland-Altman plots. RESULTS: Finally, 19 patients were eligible for analysis in this study. The value calculated by subtracting pre-CysC (mg/L) from pre-sCr (mg/dl) had a strong correlation to the decrement of serum creatinine (r = 0.9508, p < 0.0001). We added the data of 16 patients obtained from the literature to our series, which were totally randomized into 2 groups, training set and validation set in a 2:1 ratio (n = 23 and 12, respectively) to develop and validate a predictive equation for post-sCr. The mean difference between the predictive and actual post-sCr, -0.68 mg/dl (95% CI -1.62 to 0.26) in the validation set was within the limits of agreement. CONCLUSION: We showed that the discrepancy between pre-sCr and pre-CysC could predict improvement of renal function after intervention in patients with postrenal AKI.

Changes of sexual function and perception in Japanese men: A 15-year cross-sectional community-based study.

OBJECTIVES: To investigate the longitudinal changes of sexual function of Japanese men. METHODS: From 1992 to 1993, we carried out a cross-sectional community-based study on sexual function in Japanese men aged 40-79 years. After 15 years, a follow-up study was carried out to determine longitudinal changes of their sexual function. Of the 319 participants in the initial study, 135 participated again in the follow-up study. Sexual function was assessed using the same validated questionnaire in the two studies. RESULTS: Erectile rigidity declined in men of each age decade at baseline (40s, 50s, 60s and 70s) of the initial study (P < 0.01, <0.01, <0.01 and <0.05). The frequency of sexual drive was significantly decreased in men aged in their 40s, 50s and 60s (P < 0.05, <0.01 and <0.01). Men aged in their 40s were dissatisfied with their decreased sexual function (P < 0.05). In contrast, men aged in their 70s were satisfied with their sexual life (P < 0.01). CONCLUSIONS: Over a 15-year period, the sexual function of Japanese men declined in each age decade. However, the perception of this decline differed among different age group. Most elderly Japanese men did not worry about their impaired sexual function.

CLINICAL FEATURES OF 15 PATIENTS UNDER SURVEILLANCE FOR RENAL MASSES.

(Objective) We investigated the clinical features of patients under surveillance for localized renal masses. (Methods) This study was a retrospective analysis of 15 patients who were diagnosed as having clinically localized renal cell carcinoma and were placed under surveillance and 68 patients who underwent immediate radical operation for renal masses. (Results) The age at diagnosis in the surveillance group was significantly higher than in the immediate operation group (median, 81 vs. 65 years, respectively, P<0.01). The Charlson Comorbidity Index in the surveillance group was significantly higher than in the immediate operation group (median, 5 vs. 2, respectively, P<0.01) and 10 patients (67%) had complications, which was one of the reasons for surveillance. The median initial tumor size in the surveillance group was 2.5 cm (1.5-10.1). There was no significant difference in the tumor size between the two groups. During a median follow-up of 19 months (6-55) the median tumor growth rate was 0.29 cm per year (-0.19-0.65) in the surveillance group. Of the 15 patients with computed tomography follow-up, four underwent surgical resection of the renal masses after surveillance. The histological diagnosis was clear cell renal cell carcinoma in all four. During follow-up, two patients died of other causes and one patient had bone metastasis but there was no death related to the renal masses in the surveillance group. (Conclusions) The appropriateness of the surveillance should be considered when we initiate surveillance for patients with renal masses because metastasis was detected in one patient in this study. On the other hand, surveillance may be an acceptable management method for elderly or severely comorbid patients because there were two deaths from other causes in the surveillance group.

[Polyorchidism: a case report and review of the literature].

A 10-year-old boy presented with a painless left scrotal mass that had been present for 2 years. Ultrasound examination revealed 2 left testes measuring 2.4 ml and 1.0 ml with the same echogenicity. Atsurgery, there were 2 similarly sized testes connecting with other spermatic vascular, but the supernumerary testis had no connection with the vas deferens. Histological findings showed immature testicular tissue without malignancy. We report the 26th case of polyorchidism in Japan and discuss this condition.

[Clinical features of six patients with pancreas metastasis from renal cell carcinoma].

We retrospectively reviewed patients who underwent radical or partial nephrectomy and were followed up in Oji General Hospital from 1992 through 2012. A total of 6 patients had disease recurrence in the pancreas during follow-up. We investigated their clinical features and treatment outcomes. The median age at diagnosis was 75 years. The median interval from nephrectomy to the detection of pancreatic metastasis was 114 months. As local therapy for metastasis, surgical resection was selected for 4 patients. On the other hand, administration of medication, including interferon alpha and sunitinib was selected for 2 patients with other simultaneous metastatic sites. One of the 4 patients with surgical resection had disease recurrence in the residual pancreas and needed additional excision. At the median follow-up of 38 months after treatment of pancreatic metastasis, one patient remained alive without evidence of disease, 3 patients were alive with recurrent disease, and 2 patients had died of the disease.

[Rhabdomyolysis after radical nephrectomy in the lateral decubitus position: report of 2 cases].

Rhabdomyolysis is a rare perioperative complication, however, potentially lead to fatal outcome. We experienced 2 cases of rhabdomyolysis after radical nephrectomy and nephroureterectomy in the lateral decubitus position. (Case 1) A 40-years old man was seen in our hospital because of asymptomatic grosshematuria. Computed tomography revealed right renal pelvic cancer, cT3N0M0. Right radical nephroureterectomy, lymph node dissection, partial cystectomy was underwent, and the operation was finished without any trouble. At the post-operative day 1, serum creatinine level was elevated to the point of 4.2 mg/dl, and serum creatine kinase was 1,945 IU/l. Continuous hemodiafiltration (CHDF) was done at intensive-care unit (ICU), and serum creatinine and creatine kinase level were decreased. At the post-operative day 1, urine myoglobin level was prominently elevated (2,943.7 ng/ml), so we diagnosed acute renal failure due to rhabdomyolysis. (Case 2) A 40-years old man was incidentally pointed out of right renal tumor that was seen as renal cell carcinoma, cT1aN0M0. Open partial nephrectomy was underwent, and there was no trouble during the operation. After recovering from anesthesia, the patient felt left thigh pain strongly. Serum creatine kinase was 888 IU/L after the operation. At the postoperative day 1, serum creatine kinase level was markedly increased (31,138 IU/L). Serum creatinine level was 1.34 mg/dl. Urine and serum myoglobin level was prominently elevated (89,000 ng/ml and 8,634 ng/ml, respectively). We diagnosed it rhabdomyolysis, and he received large amount of fluid intravenously at intensive-care unit. Serum creatine kinase was peak out at the post-operative day 3 (20,709 IU/L), and hemodialysis was not performed.

[A case of squamous cell carcinoma of the bladder in a patient with interstitial cystitis].

A 60-year-old woman with interstitial cystitis (IC), who had previously received hydrodistention surgery, intravesical instillation of resiniferatoxin and medication, was being followed. Although urinary cytology was regularly tested with no positive findings, computed tomography carried out for screening of recurrent colon cancer showed muscle-invasive squamous cell carcinoma (SCC) of the bladder (cT3bN0M0). Cystectomy was performed, but she died due to rapid disease progression at 3 months postoperatively. Chronic inflammation can be the cause of development of SCC. It is dubious whether the specific treatments for IC affected her disease. In cases of IC with persistent pyuria, the development of SCC should be kept in mind, and affirmative examination including cystoscopy should be done regularly for early detection of the disease.

[Pathological complete response to gemcitabine and cisplatin chemotherapy for advanced upper tract urothelial carcinoma: a case report].

A 61-year-old man was referred to our hospital with the chief complaint of right leg weakness. Abdominal magnetic resonance imaging (MRI) and computed tomography (CT) demonstrated a ureteral tumor and a neighboring massive retroperitoneal tumor in addition to retroperitoneal lymph node and right renal metastases. The tumor was diagnosed as upper tract urothelial carcinoma (cT4N1M1) by percutaneous tumor biopsy. As the patient achieved a partial response after three courses of combination chemotherapy with gemcitabine and cisplatin, he received total nephroureterectomy and lymph node dissection. The pathology showed no viable cancer cells, demonstrating a pathological complete response. He remains alive after 26 months with no evidence of disease.

Inhibition of FGFR Reactivates IFNγ Signaling in Tumor Cells to Enhance the Combined Antitumor Activity of Lenvatinib with Anti-PD-1 Antibodies.

Combination therapies consisting of immune checkpoint inhibitors plus anti-VEGF therapy show enhanced antitumor activity and are approved treatments for patients with renal cell carcinoma (RCC). The immunosuppressive roles of VEGF in the tumor microenvironment are well studied, but those of FGF/FGFR signaling remain largely unknown. Lenvatinib is a receptor tyrosine kinase inhibitor that targets both VEGFR and FGFR. Here, we examine the antitumor activity of anti-PD-1 mAb combined with either lenvatinib or axitinib, a VEGFR-selective inhibitor, in RCC. Both combination treatments showed greater antitumor activity and longer survival in mouse models versus either single agent treatment, whereas anti-PD-1 mAb plus lenvatinib had enhanced antitumor activity compared with anti-PD-1 mAb plus axitinib. Flow cytometry analysis showed that lenvatinib decreased the population of tumor-associated macrophages and increased that of IFNγ-positive CD8+ T cells. Activation of FGFR signaling inhibited the IFNγ-stimulated JAK/STAT signaling pathway and decreased expression of its target genes, including B2M, CXCL10, and PD-L1. Furthermore, inhibition of FGFR signaling by lenvatinib restored the tumor response to IFNγ stimulation in mouse and human RCC cell lines. These preclinical results reveal novel roles of tumor FGFR signaling in the regulation of cancer immunity through inhibition of the IFNγ pathway, and the inhibitory activity of lenvatinib against FGFRs likely contributes to the enhanced antitumor activity of combination treatment comprising lenvatinib plus anti-PD-1 mAb. SIGNIFICANCE: FGFR pathway activation inhibits IFNγ signaling in tumor cells, and FGFR inhibition with lenvatinib enhances antitumor immunity and the activity of anti-PD-1 antibodies.

A case with fistula formation between a perinephric retroperitoneal abscess and the duodenum: successful outcome after conservative management.

A 67-year-old woman diagnosed with pyonephrosis and perinephric abscess because of an impacted urinary stone in the pelvicoureteric junction was admitted to the hospital with a high-grade fever. Although construction of a right nephrostomy for drainage of the abscess improved her general condition, she had a fever again 2 weeks after the initial treatment. Computed tomography revealed a persistent perinephric retroperitoneal abscess and a second drainage procedure was performed. Then, imaging examination revealed fistula formation between the cavity of the perinephric retroperitoneal abscess and the duodenum. The patient received conservative management including percutaneous drainage, discontinuation of oral intake, and antimicrobial chemotherapy. Three days after the second drainage and discontinuation of oral intake, imaging examination revealed complete closure of the fistula. Fistula formation between a perinephric abscess and the duodenum is very rare but a favorable outcome was obtained by our conservative management.