Recurrent epithelioid angiomyolipoma of the adrenal gland: a case report and literature review.

Background: Epithelioid angiomyolipoma (EAML), a subtype of angiomyolipoma, is distinct. It has a biologic behavior of borderline tumor, a malignant tendency, and a risk of metastasis and recurrence. Adrenal EAML is very rare. It is true that only six cases of adrenal EAML have been documented in the English-language literature. Case Description: A 65-year-old man who underwent a laparoscopic left adrenalectomy in July 2022 has adrenal EAML and this is a case report about it. The mass was surrounded by abundant blood vessels and adherence with surround-tissue. Postoperative pathology of the tumor analysis revealed adrenal epithelioid vascular smooth muscle lipoma. The patient underwent left upper abdomen and lumbar pain in July 2022. The enhanced computed tomography (CT) scan of the abdomen showed markedly enhanced masses in and around the left adrenal gland. A second left laparoscopic adrenalectomy was performed under general anesthesia. Postoperative pathology showed two taupe nodules of left adrenal, maximum diameter 0.9 to 1.1 cm. The postoperative pathological diagnosis in combination with immunohistochemistry was EAML. The patient was discharged 10 days later with symptomatic treatment with low molecular heparin. Conclusions: Adrenal EAML has a biologic behavior of borderline tumor with malignant potential and a risk of distant metastasis and recurrence. Therefore, radical surgical resection should be considered as its necessary treatment. Long-term postoperative follow-up is an important part of the treatment.

Testicular choriocarcinoma with pelvic and pulmonary metastases: a case report.

Testicular tumors represent a common form of solid tumor in young men, with choriocarcinoma of the testis being a rare, non-granulomatous germ cell tumor. It accounts for less than 0.3% of all testicular germ cell tumors. Pelvic and pulmonary metastases originating from testicular choriocarcinoma are exceptionally uncommon in men. This study describes a case of a 27-year-old male diagnosed with testicular choriocarcinoma, presenting initially with nausea, vomiting, and abdominal pain. Furthermore, this review encompasses cases of testiclar choriocarcinoma in individuals aged 30 years and below, both in China and internationally, over the past 20 years.

Massive, Retroperitoneal, Well-Differentiated Liposarcoma in Second-Trimester Pregnancy: A Report of a Rare Case.

Retroperitoneal liposarcoma during pregnancy is rare and poses significant diagnostic challenges, even for experienced specialists. We present a case report of a 27-year-old female patient, 15 weeks pregnant, who was admitted to the hospital due to a massive retroperitoneal liposarcoma. The patient underwent surgical resection of the tumor. Postoperative pathology confirmed a diagnosis of well-differentiated liposarcoma. Although liposarcoma during pregnancy is rare and challenging to diagnose, CT or MRI plays a crucial role in its detection. The recurrence rate depends on the pathological stage, histological grade, and ability to resect the tumor.

Retroperitoneal and lower extremities muscle bleeding in acquired haemophilia A (AHA): Risk factors and implications in disability and survival.

AIM: To assess risk factors of retroperitoneal and lower extremity musculoskeletal bleed in acquired haemophilia (AHA) and perform an objective assessment of disability and influence on survival. METHODS: We included 49 patients with AHA from November 2017 to May 2023. The occurrence of any retroperitoneal or/and lower extremities bleeding manifestation was investigated. On clinical follow-up, we search for compressive femoral neuropathy and quadriceps amyotrophy. The lower extremity functional scale (LEFS) was carried out one year after the last bleeding event in all AHA patients. RESULTS: A 61.2% of patients in our AHA cohort presented with any retroperitoneal and/or lower extremities musculoskeletal manifestation. Those patients had higher percentage of major bleeding EACH2/ISTH criteria (90% vs. 57%, p = .01), needs of blood transfusions (86% vs. 57% of patients, p = .03), and haemostatic by-pass products (90% vs. 63%, p = .02). Hypertension (HR 2.6, 95% CI 1.1-5.9, p = .02), presence of autoimmune disease (HR 13, 95% CI 1.7-99, p = .01), and inhibitor level > 20 BU (HR 2.6 95% CI 1.0-6.8, p = .04) significantly predicted retroperitoneal/lower extremities clinical manifestations. Most frequent sequelae were quad atrophy (30.6%) and femoral nerve palsy (20.4%). Quad atrophy and LEFS scores under 50 were associated with increased mortality (HR 3, 95% CI 1.1-8.6 and HR 12, 95% CI 3.3-45, respectively). CONCLUSION: AHA with retroperitoneal/lower extremities bleeding involvement is of greater severity and shows high disability and worst survival outcomes. Quadriceps atrophy and LEFS scale scoring under 50 predicted mortality in our AHA patients.

Understanding the Anatomy of Retroperitoneal Interfascial Space: Implications for Regional Anesthesia.

BACKGROUND: Fascial plane block techniques have evolved considerably in recent years. Unlike the conventional peripheral nerve block methods, the fascial plane block's effect can be predicted based on fascial anatomy and does not require a clear vision of the target nerves. The anatomy of the retroperitoneal interfascial space is complex, since it comprises multiple compartments, including the transversalis fascia (TF), the retroperitoneal fasciae (RF), and the peritoneum. For this reason, an in-depth, accurate understanding of the retroperitoneal interfascial space's anatomical characteristics is necessary for perceiving the related regional blocks and mechanisms that lie underlie the dissemination of local anesthetics (LAs) outside or within the various retroperitoneal compartments. OBJECTIVES: This review aims to summarize the retroperitoneum's anatomical characteristics and elucidate the various communications among different interfascial spaces as well as their clinical significance in regional blocks, including but not limited to the anterior quadratus lumborum block (QLB), the fascia iliaca compartment block (FICB), the transversalis fascia plane block (TFPB), and the preperitoneal compartment block (PCB). STUDY DESIGN: This is a narrative review of pertinent studies on the use of retroperitoneal spaces in regional anesthesia (RA). METHODS: We conducted searches in multiple databases, including PubMed, MEDLINE, and Embase, using "retroperitoneal space," "transversalis fascia," "renal fascia," "quadratus lumborum block," "nerve block," and "liquid diffusion" as some of the keywords. RESULTS: The anatomy of the retroperitoneal interfascial space has a significant influence on the injectate spread in numerous RA blocking techniques, particularly the QLB, FICB, and TFPB approaches. Furthermore, the TF is closely associated with the QLB, and the extension between the TF and iliac fascia offers a potential pathway for LAs. LIMITATIONS: The generalizability of our findings is limited by the insufficient number of randomized controlled trials (RCTs). CONCLUSIONS: Familiarity with the anatomy of the retroperitoneal fascial space could enhance our understanding of peripheral nerve blocks. By examining the circulation in the fascial space, we may gain a more comprehensive understanding of the direction and degree of injectate diffusion during RA as well as the block's plane and scope, possibly resulting in effective analgesia and fewer harmful clinical consequences.

The optimal management of large upper ureteral stones (> 1.5 cm) with infection in elderly patients: a comparative analysis of three minimally invasive surgical approaches.

PURPOSE: The aim of this study was to investigate the efficacy and safety of three minimally invasive surgical approaches for treating large upper ureteral stones complicated by infection in elderly (> 60 years) patients. METHODS: Clinical data from 95 elderly patients with large upper ureteral stones and infection, treated at our hospital between January 2018 and April 2023, were retrospectively analyzed. The surgical approaches included FURL (flexible ureteroscopic lithotripsy) 33 cases, mPCNL (minimally percutaneous nephrolithotomy) 29 cases, and RLUL (retroperitoneal laparoscopic ureterolithotomy) 33 cases. Surgical time, intraoperative blood loss, postoperative hospital stay, reoperation rate, incidence of postoperative complications, and hospitalization costs were observed and compared among the three groups. RESULTS: No statistically significant difference was found in stone clearance rates among the three groups (P > 0.05). The FURL group exhibited advantages over the mPCNL and RLUL groups in surgical time, intraoperative blood loss, and postoperative hospital stay (P < 0.05). However, it also had the highest reoperation rate and hospitalization costs (P < 0.05). RLUL demonstrated superiority over the mPCNL and RLUL groups in terms of reoperation rate, incidence of complications, and hospitalization costs (P < 0.05). Notably, mPCNL exhibited the highest complication rate at 37.9% (P < 0.05). CONCLUSION: For elderly patients with large upper ureteral stones complicated by infection, FURL, mPCNL, and RLUL represent effective surgical approaches. Further attention is needed regarding the perioperative safety of mPCNL. RLUL, which offers higher safety, efficacy, and cost-effectiveness, can be considered a primary surgical option for these patients.

Leiomyosarcoma of the abdomen and retroperitoneum; a systematic review.

Background: Intraabdominal and retroperitoneal leiomyosarcomas are rare cancers, which cause significant morbidity and mortality. Symptoms, treatment and follow up differs from other cancers, and proper diagnosis and treatment of intraabdominal and retroperitoneal leiomyosarcomas is of utmost importance. We performed a systematic review to collect and summarize available evidence for diagnosis and treatment for these tumours. Methods: We performed a systematic literature search of Pubmed from the earliest entry possible, until January 2021. Our search phrase was (((((colon) OR (rectum)) OR (intestine)) OR (abdomen)) OR (retroperitoneum)) AND (leiomyosarcoma). All hits were evaluated by two of the authors. Results: Our predefined search identified 1983 hits, we selected 218 hits and retrieved full-text copies of these. 144 studies were included in the review. Discussion: This review summarizes the current knowledge and evidence on non-uterine abdominal and retroperitoneal leiomyosarcomas. The review has revealed a lack of high-quality evidence, and randomized clinical trials. There is a great need for more substantial and high-quality research in the area of leiomyosarcomas of the abdomen and retroperitoneum. Systematic Review Registration: PROSPERO, identifier, CRD42023480527.

Giant retroperitoneal hemolymphangioma: A case report and review of literature.

BACKGROUND: Hemolymphangioma is a very rare benign tumor in clinical practice caused by abnormalities of the vasculature. Its clinical features are often atypical, and it is easy to miss and misdiagnose. When the time of nuclear magnetic T1 is significantly reduced, the diagnosis of hemangioma should be considered. Therefore, we report this case in the hope of raising clinicians' awareness of the disease. CASE SUMMARY: A 37-year-old man presented with a giant retroperitoneal hemolymphangioma. Computed tomography and magnetic resonance imaging indicated the possibility of a large perirenal lymphatic cyst. The postoperative pathological diagnosis is retroperitoneal hemolymphangioma. The patient underwent surgical excision after adequate drainage. The postoperative recovery was smooth and there were no complications. There was no recurrence during half a year of follow-up. CONCLUSION: This case reiterates that large retroperitoneal cystic masses with significantly shortened nuclear T1 time should be considered hemolymphangioma. Specific clinical basis and experience for the diagnosis and treatment of these diseases is necessary.

Da Vinci robot-assisted retroperitoneal tumor resection in 105 patients: a single-center experience.

Background: The Da Vinci Surgical System (DVSS) has the advantages of minimal invasion, rapid recovery, safety, and reliability. Although the DVSS has been widely used in various abdominal surgeries, descriptions of its use in robot-assisted retroperitoneal tumor resection (RRTR) are limited to case reports; large-sample systematic studies are lacking. The present study was performed to analyze the data of RRTR in our center, summarize our experience, and provide a reference for other retroperitoneal tumor centers. Methods: We retrospectively analyzed the clinical data of 105 patients who underwent RRTR at the Affiliated Hospital of Qingdao University from January 2015 to December 2022. Logistic univariate and multivariate analyses were performed to identify independent risk factors affecting RRTR. A receiver operating characteristic curve was used to find the cut-off value, which was then included in the logistic multivariate analysis for verification. Results: Among the 105 patients, 87 successfully underwent RRTR (DVSS group) and 18 underwent conversion to open surgery (conversion group). There was no significant difference in sex, age, body mass index, history of abdominal surgery, or tumor location between the two groups (P > 0.05). The maximum tumor diameter [odds ratio (OR), 1.041; 95% confidence interval (CI), 1.015-1.067; P = 0.002] and pathological property (OR, 8.646; 95% CI, 2.370-31.544; P = 0.001) were independent risk factors for conversion to open surgery. Further analysis confirmed that the success rate of RRTR was higher for tumors with a maximum diameter of ≤64 mm and benign tumors. Based on our experience and statistical results, we believe that retroperitoneal tumors that meet the following criteria have a higher success rate of DVSS resection: maximum tumor diameter of ≤64 mm, benign tumors, the tumor has relatively clear boundary, no obvious invasion of surrounding tissues and organs, and no need for combined organ resection. Conclusions: RRTR is safe and effective in the treatment of RPT, and the clinical prognosis is similar to that of open surgery. The success rate of RRTR in patients with appropriate surgical indications for this procedure is higher.

Case report: A case with atypical presentation oftesticular choriocarcinoma.

Testicular choriocarcinoma is a relatively rare malignancy with a highly aggressive nature. Timely diagnosis and treatment can help prolong the survival of patients and even cure them. This case reports a 29-year-old male who presented to the clinic for a month with epigastric pain. On examination, a massive mass of approximately 9*10 cm could be palpated in the upper abdomen. When asked about his previous history, the patient only described a history of a right inguinal hernia that had been repaired 12 years earlier. The admission diagnosis was considered the retroperitoneal tumor, which was found to have metastasized to the liver and lungs after the completion of relevant tests. We then performed a CT-guided lune puncture biopsy on day 8 of admission. The biopsy pathology suggested metastatic cancer was considered. As the symptoms of tumor compression gradually worsened, we performed surgical treatment (retroperitoneal tumor resection + partial duodenal resection + enteroanastomosis) on day 13 of admission. The postoperative pathology was choriocarcinoma. We subsequently conducted a detailed inquiry with the patient's family about his medical history and found a history of inguinal testicle. Through testicular ultrasound examination, it was preliminarily determined to be testicular choriocarcinoma (not yet pathologically confirmed). We wanted to start salvage chemotherapy as soon as possible after surgery. However, the patient's postoperative condition was poor, with rapid progression of hepatopulmonary metastases and gradually increased thyrotoxicosis, and we started salvage chemotherapy (EP regimen: etoposide and cisplatin) on postoperative day 12. However, the patient was forced to stop due to a severe chemotherapy reaction and died of respiratory and cardiac arrest in the hospital. For male patients with retroperitoneal mass, the possibility of germ-cell neoplasm should first be excluded. By inquiring in detail about a history of cryptorchidism and in the initial days of hospitalization, testicular exploration, ultrasounds, and serum tumor markers (AFP, ß-HCG) tests can be conducted to rule out the possibility of germ-cell neoplasm, thereby preventing misdiagnosis and treatment delays. If the clinical diagnosis is metastatic germ-cell tumor with severe symptoms of metastatic disease, surgery should never be used as the initial treatment.

Mature Cystic Teratoma in a Newborn With Down Syndrome.

Retroperitoneal teratomas are uncommon neoplasms that cause diagnostic dilemmas in neonates during the evaluation of abdominal cystic mass lesions. Down syndrome (DS) is a chromosomal abnormality with an extra third copy of chromosome 21. Due to chromosomal instability, DS is inferred to be a cancer predisposition syndrome. The malignancy pattern in DS is unique with higher incidence of hematological malignancies and solid tumors are rarely reported. Down syndrome neonate was incidentally diagnosed with a retroperitoneal cystic lesion along the left kidney during evaluation for poor feeding on ultrasonography, raising suspicion of an adrenal hemorrhagic cyst. CECT abdomen and pelvis revealed complex cystic lesions along the left renal hilum, with the possibility of cystic neuroblastoma, retroperitoneal cystic teratoma, and cystic lymphangioma. Tumor markers were within normal limits. Surgical exploration revealed a left renal hilar solitary cystic mass lesion, which was excised in toto with a probable intraoperative diagnosis of cystic lymphangioma. The postoperative course was uneventful. Histopathological examination confirmed that the lesion was a mature cystic teratoma. The child is doing well postoperatively at the one-year follow-up. Neonatal retroperitoneal teratomas are unusual neoplasms. A favorable outcome can be achieved, with early diagnosis and treatment.

Diagnostic Approach to IgG4-Related Retroperitoneal Fibrosis After Colorectal Cancer Surgery in a Patient With Normal IgG4 Levels: A Case Report.

An asymptomatic 75-year-old man who underwent transverse colon cancer surgery two years previously presented with retroperitoneal fibrosis (RPF) around the ventral sacral and right external iliac artery and vein on abdominal computed tomography (CT) during a routine surveillance visit. We assumed cancer recurrence or immunoglobulin G4 (IgG4)-related disease (RD), but although generic tumor markers and IgG4 levels were normal, soluble interleukin 2 receptor (sIL-2R) was elevated at 569 U/mL (reference: 122-496 U/mL). No diagnosis was made at this time, and the patient was followed up. He subsequently developed edema of both lower extremities. Abdominal enhanced CT showed an enlarged RPF without invasion of surrounding organs and with a delayed contrast effect, and positron emission tomography-CT showed fluorodeoxyglucose accumulation in the same area but a lower standardized uptake value (SUV) than at the time of transverse colon cancer diagnosis. Although generic tumor markers and IgG4 levels remained within the reference range, sIL-2R was further elevated to 1100 U/mL. An open biopsy and histopathology showed a high IgG4/IgG-positive cell ratio and infiltration of IgG4-positive plasma cells. The patient was finally diagnosed with IgG4-RD RPF. In cases of RPF after colorectal cancer surgery, the combined findings of elevated sIL-2R, lack of infiltration into surrounding organs, and lower SUV values ​​than at the cancer site could provide useful information to aid the diagnosis of IgG4-RD RPF.

Sentinel node mapping decreases the risk of failed detection of isolated positive para-aortic lymph node in endometrial cancer.

BACKGROUND: Isolated positive para-aortic lymph node metastasis in endometrial cancer is an uncommon event, ranging from 1% to 3%. OBJECTIVE: Our aim was to evaluate the impact of sentinel lymph node (SLN) mapping on the risk of isolated positive para-aortic lymph node metastasis. METHODS: We retrospectively evaluated a series of 426 patients who underwent SLN mapping with at least one SLN detected from January 2013 to December 2021 (SLN group) compared with a historical series of 209 cases who underwent a systematic pelvic and para-aortic lymphadenectomy between June 2007 and April 2015 (LND group). Isolated para-aortic lymph node metastasis recurrences were included in the SLN group analysis. RESULTS: In the SLN group, 168 cases (39.4%) had backup systematic lymphadenectomy, and 56 (13.1%) had positive lymph nodes compared with 34 (16.3%) in LND group (p=0.18). The SLN group had higher rates of minimally invasive surgeries (p<0.001) and presence of lymphovascular space invasion (p<0.001). Moreover, SLN group had fewer other uterine risk factors, such as high-grade tumors (p<0.001), and deep myometrial invasion (p<0.001). We found that SLN mapped outside the pelvis at pre-sacral, common iliac areas, and para-aortic regions in 2.8% (n=12), 11.5% (n=49), and 1.6% (n=7) of cases, respectively. Overall, 52 (12.2%) patients had positive SLNs, and 3 (5.7%) positive SLNs were found outside the pelvis-one in the pre-sacral region, one in the common iliac area, and one in the para-aortic region. An isolated para-aortic lymph node was found in only 2 (0.5%) cases in the SLN group compared with 7 (3.3%) cases in the LND group (p=0.004). CONCLUSIONS: SLN protocol accurately predicts lymph node status and may decrease the risk of failed identification of isolated para-aortic lymph node metastasis compared with systematic lymphadenectomy.

Retroperitoneal infantile hemangioma: a case report and literature review.

BACKGROUND: Retroperitoneal infantile hemangioma (RIH), a type of primary retroperitoneal tumors, are exceptionally rare in clinical practice. Infantile hemangiomas typically manifest on the skin's surface. RIHs are exceptionally rare and typically small. In adults, these tumors often manifest without specific clinical symptoms or detectable signs for a definitive diagnosis. This case report details a patient diagnosed with RIH. We recommend complete excision of the tumor after a comprehensive evaluation, followed by postoperative pathology, to achieve a conclusive diagnosis. We believe that managing critical retroperitoneal structures and vessels intraoperatively presents a significant challenge for all procedures involving primary retroperitoneal tumors. A 47-year-old male was diagnosed with gallstones and underwent surgery 3 months ago at other institution for unexplained nausea and vomiting. Follow-up imaging 2 months after surgery revealed a retroperitoneal mass below the left renal pole. Upon presentation to our hospital, the patient continued to experience intermittent nausea and vomiting, with no other significant symptoms or signs. Considering the patient's 8-year history of hypertension, a paraganglioma was initially suspected. We performed the laparoscopic mass resection after a detailed assessment. However, postoperative pathology revealed it a capillary hemangioma (old term)/infantile hemangioma. CONCLUSION: RIHs are exceedingly rare benign tumor. The possibility of malignancy should be ruled out, and surgical resection is recommended following a thorough evaluation, with the diagnosis confirmed through pathological examination.

Retroperitoneal Extension of a Fistula-in-Ano: A Case Report.

Fistula-in-ano and anorectal abscesses are commonly encountered in surgical departments, but their extension into the retroperitoneum and pelvis to form an extensive collection is rare. Here, we present the case of a 66-year-old diabetic male who presented with lower abdominal pain and fever for a day, with signs of sepsis. He had a simple fistula in the perianal region for the past 15 years. Radiological studies showed that the fistulous tract was complex which extended superiorly into the supralevator space and the retroperitoneum and formed a localized collection in the pelvis. The dependent part of the collection was drained using minimally invasive techniques, and the remnant collection was surgically drained through a perianal approach. The patient's condition improved with further treatment and local wound care, and he was subsequently discharged.

IgG4-Related Retroperitoneal Fibrosis in a Patient With B-Cell Lymphoproliferative Disorder.

We report an interesting case of a 25-year-old male patient who presented with a complaint of pain in the abdomen for six months, which was not associated with any other symptom, the patient was diagnosed with IgG4-related retroperitoneal fibrosis (RF) via endoscopic ultrasound (EUS)-guided biopsy. He was prescribed steroids and proton pump inhibitors. Due to the limited presentation and rarity of RF, diagnosis of this disease requires extensive diligence and care. In this case report, we underscore the importance of considering the differential diagnosis of RF or Ormond's disease when a patient presents with vague symptoms of pain in the abdomen. According to our knowledge, this is the first case of IgG4-related RF in a patient with B-cell lymphoproliferative disorder reported from Pakistan.

Histology-Tailored Approach to Soft Tissue Sarcoma.

Soft tissue sarcomas are a diverse and heterogeneous group of cancers of mesenchymal origin. Each histological type of soft tissue sarcoma has unique clinical particularities, which makes them challenging to diagnose and treat. Multidisciplinary management of these rare diseases is thus key for improved survival. The role of surgery has been well established, and it represents the cornerstone curative treatment for soft tissue sarcomas. To date, local recurrence is the leading cause of death in low-grade sarcomas located at critical sites, and distant metastasis in high-grade sarcomas, regardless of the site of origin. Management must be tailored to each individual histologic type. We describe the most common types of extremity, trunk, abdominal, and retroperitoneal soft tissue sarcoma along with characteristics to consider for optimized management.

Learning curve in retroperitoneal sarcoma surgery.

INTRODUCTION: Retroperitoneal sarcoma (RPS) surgery poses unique challenges. This retrospective study aimed to analyze the learning curve (LC) in RPS surgery, assessing the relationship between surgical experience and outcomes. MATERIALS AND METHODS: Cumulative sum (CUSUM) analysis was used to analyze 62 RPS surgeries performed by a single surgeon between 2016 and 2022 at our center. RESULTS: The number of cases where the surgeon acted as first operator increased from 3 in 2016 to 13 in 2022. The surgeon operated with his mentor in 66.7 % of cases in 2016, whereas in 7.7 % of cases in 2022. LC consisted of 3 phases. Phase 1 (16 cases), with a negative slope, represented shorter operative time (OT) and fewer number of resected organs (RO). Phase 2 (30 cases) was the plateau phase. Phase 3 (16 cases), with a positive slope, indicated longer OT and more RO. Statistically significant differences were observed in terms of size (p = 0.003), presentation (p = 0.048), number of resected organs (p = 0.046), pattern of resection (p = 0.033), OT (p = 0.006), and length of stay (p = 0.026) between the three phases. CONCLUSION: This study focused on the critical role of LC in RPS surgery, emphasizing its influence on outcomes. We identified three phases, highlighting the surgeon's evolution. This offers a framework for educating sarcoma surgeons and ensuring exposure to increasing surgical complexity. In discussions on sarcoma referral centers and the correlation between case volume and outcomes, this study underlines the importance of evaluating LC to distinguish surgeons qualified to manage sarcoma cases within a referral center.

A Case of Idiopathic Retroperitoneal Fibrosis Triggering Recurrent Gastrointestinal Bleeding.

Idiopathic retroperitoneal fibrosis (IRF) is a rare condition characterized by fibrous tissue proliferation in the retroperitoneal space, commonly affecting the ureters and other abdominal structures. This case report describes a previously undocumented presentation of IRF in a 52-year-old female, who presented with recurrent gastrointestinal bleeding and severe anemia over six months. Diagnostic workup included endoscopy, colonoscopy, abdominal computed tomography (CT), and biopsy, revealing fibrous encasement of the mesenteric vessels leading to ischemic damage and gastrointestinal bleeding. Treatment involved high-dose corticosteroids and surgical resection of the fibrotic tissue, which resulted in complete resolution of symptoms. The aim of this case report is to highlight this unique presentation of IRF, discuss the diagnostic challenges, and explore effective treatment strategies for managing this rare but significant complication.

Subcutaneous ureteral bypass for treatment of proximal ureteral obstruction secondary to retroperitoneal fibrosis after renal transplantation in a cat.

Case summary: A 5.5-year-old male neutered domestic shorthair cat was presented with a 2-year history of progressive chronic kidney disease. Abdominal ultrasonography revealed bilateral chronic renal degeneration, nephrolithiasis, cortical hyperechogenicity and infarction. Left orthotopic renal transplantation was performed using the Synovis vascular coupling system for end-to-end anastomosis of the renal arteries and veins. Two months after transplantation, renal values were elevated, and abdominal ultrasonography revealed hydronephrosis and hydroureter of the transplanted kidney. Fluoroscopic antegrade pyelography identified a proximal ureteral stricture. Proximal neoureterocystostomy was performed and renal values normalized postoperatively. The cat was re-evaluated for acute stranguria and severe azotemia 12 months later. Contrast-enhanced CT revealed severe hydronephrosis of the transplanted kidney, obstruction of the proximal ureter and adhesions to the urinary bladder. Upon exploration, retroperitoneal fibrosis was found covering the transplanted kidney. Given the clinical situation, a subcutaneous ureteral bypass device (SUB) was placed. Clinicopathologic analyses, trough cyclosporine levels, aerobic urine cultures and ultrasonographic evaluations of the transplanted kidney were monitored every 1-3 months. Patency of the SUB was reassessed every 3-6 months. At 15 months after placement, the SUB occluded due to kinking of the cystostomy catheter and was replaced. At 28 months after SUB placement, renal function and clinical status deteriorated, and the cat was euthanized. Relevance and novel information: To the authors' knowledge, this is the first report of a SUB device being used for management of ureteral obstruction in a transplanted kidney in a cat.