Retroperitoneal Tumor Research Articles

Mixed reality in primary retroperitoneal tumour surgery: Evaluation of preoperative and intraoperative application value.

To evaluate the feasibility and application value of mixed reality technology (MR) in Primary retroperitoneal tumour (PRT) surgery. From 276 patients who underwent PRT resection at the First Affiliated Hospital of Xi'an Jiaotong University, we screened 46 patients who underwent MR-assisted retroperitoneal tumour resection and 46 patients who underwent tumour resection without MR assistance. The intraoperative and postoperative recovery of the patients in both groups were compared, and the reliability and validity of the application of MR were further examined using the Likert scale. There was a significant difference in the mean intraoperative bleeding volume between the two groups, but it was reduced in the MR group. The resultsof the Likert scale showed higher scores in the MR group than non-MR group. MR can be used to assist PRT resection and has great potential to improve the rate of complete retroperitoneal tumour resection.

Area of combined surgical interventions, including those with an angiosurgical component, in terms of malignant non-organ retroperitoneal tumors’ treatment

Purpose of the study. To analyze the immediate outcomes following surgical treatment of locally advanced malignant non-organ retroperitoneal tumors (NRT).Materials and methods. Surgical interventions for malignant NRTs were performed in 114 patients at Abdominal Oncology Department № 1, National Medical Research Centre for Oncology.There were 48 males and 66 females among them. According to the histological structure, liposarcoma was commonly detected in 64 (56.1 %) cases.Results. Intraoperative revision revealed the spread of the tumor to adjacent anatomical structures in 67 (58.8 %) cases. Resection surgical interventions were performed in 109 patients, of which 106 (97.2 %) patients had operations performed in an amount of R0. Combined surgical interventions for NRTs were performed in 62 (54.4 %) patients, and multiorgan happened to be in 45 (72.6 %) patients out of those. Resection of the inferior vena cava was performed in 12 patients. Resection of the superior mesenteric vein was performed in 2 patients and the iliac-colonic vein in 2 patients. In 1 observation the left renal vein was resected with suturing of the lateral defect of the vessel wall. Complications during surgery and in the early postoperative period were noted in 14 (12.3 %) patients. In total, 2 patients died after operations, the mortality rate was 1.8 %.Conclusions. Tumor invasion of big main blood vessels is not a contraindication for surgical treatment of locally spread malignant non-organ retroperitoneal tumors.

OP09.04: Imaging in gynecological disease: clinical and ultrasound characteristics of benign retroperitoneal pelvic nerve sheath tumours

OP09.04: Imaging in gynecological disease: clinical and ultrasound characteristics of benign retroperitoneal pelvic nerve sheath tumours

Planning Target Volume Margin Quantification of Retroperitoneal Tumors Using Robotic Stereotactic Body Radiotherapy with Spine Tracking

Stereotactic body radiotherapy treatment (SBRT) is an effective modality for treating primary and oligometastatic malignant lesions. Appropriate planning target volume (PTV) margins are essential when delivering SBRT to maximize target prescription coverage while minimizing dose to surrounding organs-at-risk. Spine tracking uses boney spinal anatomy as a surrogate for tumor localization during treatment delivery on robotic linear accelerator platforms that employ intrafraction kV x-ray imaging. The aim of this study was to quantify the PTV margin needed when spine tracking was used for tumor localization when treating retroperitoneal metastatic lesions with robotic SBRT. A single institution chart review was performed and identified 16 patients with retroperitoneal tumors treated stereotactically over 19 courses in 103 fractions. Daily cone-beam computed tomography (CBCT) images that were registered based on tumor position at the time of treatment were analyzed. Rigid registrations were re-performed aligning the position of the spine on the CBCT relative to its position on the planning CT. Shifts from the treatment position were recorded and per-patient mean shifts and standard deviations were calculated. Van Herk's margin recipe was used to determine the additional PTV margin required if spine tracking was used instead of soft tissue alignment. Patient tumors were stratified and compared based on proximity to the vertebral column (≤1 cm vs >1 cm) and location within the retroperitoneum (superior vs inferior to the renal artery). Student's t-test was used to compare statistical differences of shifts based on location. The additional margins calculated by van Herk's margin recipe to adequately cover the target volumes within the 95% isodose surface for 90% of the entire patient cohort in the vertical, longitudinal, and lateral directions were 2.7, 2.8, and 2.8 mm, respectively. When tumors were stratified by proximity to the vertebral column, average longitudinal (p<0.001) and total shifts (p<0.001) were statistically significant. Isometric PTV expansions of 3, 4, and 5 mm would have encompassed 55%, 76%, and 86% of the maximum total shifts for lesions >1 cm from the vertebral column versus 94%, 100%, and 100% for lesions ≤1 cm. When stratified by location within the retroperitoneum, isometric PTV expansions of 3, 4, and 5 mm would have encompassed 82%, 94%, and 100% of the maximum total shifts for lesions superior to the renal artery versus 78%, 94%, and 98% for lesions inferior to the renal artery. When treating retroperitoneal tumors with robotic SBRT, a minimum isometric margin expansion between 3 to 5 mm when creating the PTV is recommended if spine tracking is used for intrafraction tumor localization. Target volumes adjacent to the vertebral column may have PTV margins decreased to ≤4 mm without compromising target coverage.

Large functional retroperitoneal paraganglioma: A surgical challenge

ABSTRACT Paraganglioma is relatively rare retroperitoneal tumors. If functional retroperitoneal paragangliomas are misdiagnosed, surgical intervention can precipitate intraoperative hypertensive crises which may have serious consequences. We present a case of a 40-year-old female who presented with a large functional right-sided retroperitoneal paraganglioma encasing the inferior vena cava (IVC). The patient underwent paraganglioma excision with IVC resection with right nephrectomy. Such complex multivisceral resections require surgical expertise and are feasible at high-volume centers experienced in performing retroperitoneal surgeries.

Incidence, risk factors, and outcomes of venous thromboembolism in patients undergoing surgery for retroperitoneal tumors: A propensity-matched retrospective cohort study.

Venous thromboembolism (VTE) is a common postoperative complication; however, incidence and risk stratification of postoperative VTE in patients with retroperitoneal tumor remains unclear. We aim to quantify incidence, identify risk factors, and determine outcomes of VTE in patients undergoing retroperitoneal tumor surgery. We retrospectively reviewed characteristics, perioperative outcomes, and overall survival (OS) of patients (VTE and non-VTE) who underwent retroperitoneal tumor surgery between 2015 and 2020. Perioperative and oncologic outcomes were compared using propensity-matching and Cox analyses. Of 1223 patients with retroperitoneal tumor surgery, 2.1% had VTE. Age (odds ratio [OR] 1.140, 95% confidence interval [CI] 1.053-1.239, P=0.004), recurrence (OR 1.851, 95% CI 1.241-2.761, P=0.003), and vascular resection (OR 2.036, 95% CI 1.054-3.934, P=0.034) were independent risk factors, with significant between-group differences regarding age, recurrence, sarcoma, organ resection, vascular resection, and operation time. No between-group differences in 30-day all-cause mortality (8% vs. 4%, OR 0.657, 95% CI 0.375-1.151, P=0.427) and major complications (12% vs. 8%, OR 0.775, 95% CI 0.483-1.244, P=0.572) were observed. Mean hospitalization duration (20.1 vs. 22.9d, OR 1.153, 95% CI 1.022-1.386, P=0.033) and ICU stay (3.2 vs. 5.5d, OR 1.193, 95% CI 1.034-1.347, P=0.012) were shorter in non-VTE versus VTE, respectively, with inferior OS (hazard ratio [HR] 2.090, 95% CI 1.014-4.308, P=0.046) in VTE. Age, recurrence, and vascular resection are positively associated with VTE, which is associated with inferior OS.

Retroperitoneal capillary arteriovenous malformation mimicking a malignant neoplasm

IntroductionRetroperitoneal tumors account for 0.2% of all neoplasms. Among these tumors, retroperitoneal vascular malformations are particularly rare, with most previously reported cases being venous malformations.Case presentationA 72‐year‐old woman was diagnosed with a retroperitoneal tumor on abdominal computed tomography. The 27‐mm diameter tumor was located away from the right kidney and major vessels in the right perirenal adipose tissue. Contrast‐enhanced computed tomography revealed a heterogeneously enhanced tumor with well‐defined borders. Dynamic contrast‐enhanced magnetic resonance imaging revealed rapid enhancement in the arterial phase and a progressive filling‐in pattern in the delayed phase. Although vascular malformation was suspected, a definitive diagnosis could not be established. The retroperitoneal tumor was excised laparoscopically for therapeutic and diagnostic purposes, and the histopathological diagnosis confirmed it as a capillary arteriovenous malformation.ConclusionHerein, we presented a rare case of retroperitoneal capillary arteriovenous malformation that was difficult to definitively diagnose preoperatively.

Solid pseudopapillary epithelial neoplasm of pancreas presenting as an abdominal lump: a case report

Solid pseudopapillary epithelial neoplasm (SPEN) of the pancreas is a rare cystic exocrine tumour of the pancreas that predominantly affects women between 30 and 40 years of age. This case report aims to describe clinical presentation and management of SPEN. We report a case of 20 years old female who presented with palpable lump in upper abdomen and continuous dull aching pain. Preoperative contrast enhanced computed tomography (CECT) abdomen was suggestive of large solid mass of size 11×10×10 cm with liquified content in relation to tail of pancreas with a possibility of retroperitoneal tumour or gastrointestinal tumour (GIST). Spleen sparing distal pancreatectomy with segmental resection of transverse colon with colo-colic anastomosis was performed and the diagnosis of SPEN was subsequently confirmed on histopathology examination. SPEN is a slow-growing tumour with a low-grade malignant potential found incidentally in asymptomatic patients. The average tumour size is about 4 to 6 cm in diameter at presentation. Distal pancreatectomy with splenectomy is the procedure of choice as described in literature. SPEN should be kept as a differential diagnosis in a young female patient presenting with vague abdominal pain and retroperitoneal lump in relation to the pancreas. Complete surgical resection is the definite treatment with a 5-year survival rate of 95%.

Surgical approach for complete resection of giant retroperitoneal liposarcoma with diaphragmatic hernia via ninth rib thoracotomy.

Resection of a giant retroperitoneal liposarcoma is difficult and technically demanding, especially for large retroperitoneal tumors accompanied by a diaphragmatic hernia. Technically, the open abdominal approach can be time-consuming and difficult to perform, with possible intraoperative complications and other factors bringing psychological and physical difficulties to the patient. This study reports a safe and feasible approach for the complete resection of a large retroperitoneal tumor complicated by a diaphragmatic hernia. A 58-year-old male patient with persistent upper abdominal pain and distension was treated at a local hospital on 4 July 2022. Computed tomography showed a mixed-density mass on the right retroperitoneum, and liposarcoma was considered. On 6 July 2022, the patient was transferred to our hospital for further treatment. Computed tomography showed a mass with low-density fatty shadow in the right adrenal region. The boundary with the right adrenal gland was unclear. The mass was 102mm × 74mm, and the right lobe of the liver was compressed. Insufficiency of the right middle lobe of the liver was seen due to a right diaphragmatic hernia and left mediastinal deviation. We considered the traditional approach for tumor resection via laparotomy, but we opted to perform a comprehensive evaluation first. The tumor was close to the back of the right kidney and liver, causing the diaphragm to rise because of its proximity to these organs. Exposing the tumor through laparotomy would be difficult, making it challenging to remove. The patient had a diaphragmatic hernia and moderate pulmonary dysfunction; therefore, we decided to enter the abdomen through a thoracotomy of the ninth rib. Using our technique, the tumor was easily visualized and completely removed in approximately 30min. The intraoperative blood loss was 100ml, and no postoperative bleeding, pneumothorax, intestinal fistula, infection, or other complications occurred. The transthoracic approach may be a safer and more feasible resection method than the traditional open approach for patients with giant retroperitoneal liposarcoma with a diaphragmatic hernia.

Ferroptosis triggered by STAT1- IRF1-ACSL4 pathway was involved in radiation-induced intestinal injury

Radiation-induced intestinal injury (RIII), a common gastrointestinal complication caused by radiotherapy on pelvic, abdominal and retroperitoneal tumors, seriously affects the life quality of patients and may result in termination of radiotherapy. At present, the pathogenesis of RIII has not been fully understood. Herein, we demonstrated that ferroptosis played a critical role in RIII occurrence. The RNA sequencing analysis strongly hinted ferroptosis was involved in RIII mice. In line with this, the levels of 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA), markers of lipid peroxidation, remarkably increased in RIII mice. And the ferroptosis inhibitor, Ferrostatin-1 (Fer-1), improved the mice survival and alleviated intestinal fibrosis in vivo. Moreover, our results revealed that arachidonic acid (AA) enhanced ferroptosis in cultured intestinal epithelial cells (IECs) and organoids in vitro after irradiation, and AA gavage aggravated RIII in mice. Mechanistic studies revealed the level of ACSL4 protein significantly increased in mouse jejunums and IECs after irradiation. Radiation-induced ferroptosis in IECs was also prevented following ACSL4 knockdown or with the function inhibitor of ACSL4. Furthermore, we found that transcription of ACSL4 induced by irradiation was regulated by STAT1/IRF1 axis, and AMPK activation triggered by AA negatively regulated radiation-induced ferroptosis. Taken together, our results suggest that ferroptosis mediates RIII and reducing dietary AA intake as well as targeting the STAT1-IRF1-ACSL4 axis or AMPK may be the potential approaches to alleviate RIII.

Overexpression of ASPH protein predicts poor outcomes in retroperitoneal liposarcoma patients.

Overexpression of ASPH protein predicts poor outcomes in retroperitoneal liposarcoma patients.

Castleman disease. A rare clinical case of retroperitoneal tumor localization in an elderly patient

Castleman disease is an extremely rare benign disease of the lymphatic system with an estimated incidence of 1–9 cases per 1,000,000. Its etiology remains unknown; interleukin 6 (IL-6) plays an important role in pathogenesis. Castleman disease has two clinical forms: localized (up to 90 % of cases) with a favorable prognosis, treated predominantly by surgical method; generalized (up to 10 % of cases) with less favorable prognosis, treated by pharmacological therapy. The diagnosis is rarely established at the preoperative stage.The aim. To present a clinical case of diagnosis and treatment of Castleman tumor of a rare topical localization.Results. A 66-year-old patient was admitted at the Abdominal Oncology Department of the G.E. Ostroverkhov Kursk Oncology Scientific and Clinical Center.Diagnosis: Retroperitoneal mass on the right found at the preventive examination; no peripheral lymphadenopathy was detected on ultrasound and computed tomography (CT). After the examination, a preliminary diagnosis was made: Gastrointestinal stromal tumor (GIST) of the small intestine mesentery. Based on the results of the case conference, the decision was taken to perform a surgery – laparoscopic removal of the tumor under endotracheal anesthesia. For surgical approach, a fan-shaped arrangement of ports was chosen. The surgery had no complications. Intraoperative blood loss was 50.0 ml. The total operating time was 98 minutes.According to the results of the histological study, the following diagnosis was made: Castleman disease, unicentric form, hyaline-vascular variant. En bloc surgery is the standard method for the treatment of localized forms of the Castleman disease. In all cases, long-term follow-up shows a long relapse-free period in almost all patients.During follow-up examinations (ultrasound of the abdominal cavity and retroperitoneal space, CT of the abdominal cavity with contrast enhancement, CT of the chest), no disease recurrence was detected during the year of observation.Castleman disease is a rare non-clonal lymphoproliferative disease of unknown etiology. A rare case of its retroperitoneal localization indicates that in cases with an uncertain nature of the peritoneal mass, Castleman disease should be included in the differential diagnostic search.

Insight of a lipid metabolism prognostic model to identify immune landscape and potential target for retroperitoneal liposarcoma.

The exploration of lipid metabolism dysregulation may provide novel perspectives for retroperitoneal liposarcoma (RPLS). In our study, we aimed to investigate potential targets and facilitate further understanding of immune landscape in RPLS, through lipid metabolism-associated genes (LMAGs) based prognostic model. Gene expression profiles and corresponding clinical information of 234 cases were enrolled from two public databases and the largest retroperitoneal tumor research center of East China, including cohort-TCGA (n=58), cohort-GSE30929 (n=92), cohort-FD (n=50), cohort-scRNA-seq (n=4) and cohort-validation (n=30). Consensus clustering analysis was performed to identify lipid metabolism-associated molecular subtypes (LMSs). A prognostic risk model containing 13 LMAGs was established using LASSO algorithm and multivariate Cox analysis in cohort-TCGA. ESTIMATE, CIBERSORT, XCELL and MCP analyses were performed to visualize the immune landscape. WGCNA was used to identify three hub genes among the 13 model LMAGs, and preliminarily validated in both cohort-GSE30929 and cohort-FD. Moreover, TIMER was used to visualize the correlation between antigen-presenting cells and potential targets. Finally, single-cell RNA-sequencing (scRNA-seq) analysis of four RPLS and multiplexed immunohistochemistry (mIHC) were performed in cohort-validation to validate the discoveries of bioinformatics analysis. LMS1 and LMS2 were characterized as immune-infiltrated and -excluded tumors, with significant differences in molecular features and clinical prognosis, respectively. Elongation of very long chain fatty acids protein 2 (ELOVL2), the enzyme that catalyzed the elongation of long chain fatty acids, involved in the maintenance of lipid metabolism and cellular homeostasis in normal cells, was identified and negatively correlated with antigen-presenting cells and identified as a potential target in RPLS. Furthermore, ELOVL2 was enriched in LMS2 with significantly lower immunoscore and unfavorable prognosis. Finally, a high-resolution dissection through scRNA-seq was performed in four RPLS, revealing the entire tumor ecosystem and validated previous findings. The LMS subgroups and risk model based on LMAGs proposed in our study were both promising prognostic classifications for RPLS. ELOVL2 is a potential target linking lipid metabolism to immune regulations against RPLS, specifically for patients with LMS2 tumors.

Retroperitoneal Liposarcoma Presenting as Right Inguinal Hernia - A Rare Entity

Background: The purpose of this case report is to highlight a rare entity of retroperitoneal liposarcoma presenting as inguinal hernia. Difficulty in preoperative diagnosis, surgical management &amp; outcome are discussed. Pitfalls in diagnosis and management are also highlighted. Introduction: Inguinal hernia is a common condition with the majority of patients presenting in the surgical outpatient department. Retroperitoneal sarcoma projecting through the groin is very rare. In literature only 10 cases have been published over the last 30 years. Case Presentation: Middle age person presented in OPD with complaint of right Inguinal swelling for 1 &amp; ½ years. He was diagnosed with right inguinal hernia. On exploration there was a huge mass communicating to retroperitoneum. Laparotomy was done &amp; mass excised. On histopathology it was revealed to be liposarcoma. Conclusion: Sometime history, clinical examination and even investigations can be misleading but if inguinal hernia is large, growing slowly, non-reducible then retroperitoneal tumor must be ruled out carefully in differential diagnosis of hernia by extended preoperative workup.

(032) A Large Retroperitoneal Schwannoma Masquerading as Genito-Urinary Syndrome of Menopause

Abstract Introduction Retroperitoneal schwannomas are extremely rare, slow growing, benign, neurogenic tumors. Their diagnosis is challenging and often incidentally found upon evaluation of vague symptoms. Extrinsic compression to nearby organs or nerves may cause pain and paresthesia. Vulvar pain as a presenting symptom of a retroperitoneal schwannoma is reported in the literature in a case with pudendal nerve involvement. Here we present a case report of a patient who presented with vulvar burning and lower urinary tract irritative symptoms which was found to have a large infra-hepatic retroperitoneal schwannoma. Objectives In this report we show case how performing a detailed neurological evaluation and having a good understanding of the vulvar, perineal, and lower extremity dermatomal innervation have assisted in early diagnosis and treatment of a large retroperitoneal schwannoma. Methods A 65-year-old menopausal woman presented to her primary provider for a 3-month-history of worsening vulvar burning sensation associated with urinary burning, frequency, and nocturia. The pain is worse at night and when sitting for more than an hour. The patient endorsed low back pain that radiated like pins down her anterior thighs. The patient underwent evaluation by her referring provider to rule out a urinary tract infections and vaginitis. She was treated with vaginal estrogen tablets with partial relief for a working diagnosis of Urogenital Syndrome of Menopause. Patient was then referred to Gynecology due to inadequate relief. A detailed pelvic examination revealed normal labia majora and minora with no erythema or swelling. The Vestibule, Bartholin and Skene glands were non tender. Q-tip testing provoked burning sensation in the left and right labia minora on the medial and lateral aspect as well as the labia majora. Pelvic Floor evaluation elicited left pelvic floor tenderness and bilateral ischial spine pain concerning for Pudendal neuralgia. Also, noted paresthesia overlying the left lower extremity at the L3 and L4 distribution at the medial thigh (Figure-1) The patient underwent a bilateral pudendal block with total resolution of her vulvar pain for 24 hours and hence, lumbar and pelvic nerve entrapment was suspected. Magnetic Resonance Imaging was requested. Evaluation revealed a 3.3x4.4cm left ovarian mass and uterine fibroids that could potentially explain L2-L5 radiculopathy. The Lumbar MRI noted a cystic mass in the right mid abdomen for which further evaluation with CT scan was recommended. (Image-1). Referral to Surgical Oncology and Gyn oncology was sought. Epithelial ovarian cancer tumor markers were normal. Catecholamine studies were nonrevealing except for unexplained increase in dopamine levels. Results Surgical excision of the retroperitoneal and ovarian tumor revealed a left ovarian Fibroma and Schwannoma with Cystic Degeneration, confirmed with Immuno-peroxidase studies for S100 and SOX10. The patient had an uncomplicated post-operative course and remains asymptomatic with total resolution of her urinary and vulvar burning symptoms. Conclusions This a case report of vulvar and urethral paresthesia caused by an exceedingly rare tumor located high in the retroperitoneum. Diagnosis was aided by detailed history, comprehensive gynecological, and neurodermatomal evaluation. Appropriate imaging and timely referral led to early diagnosis and treatment, resulting in symptom resolution. Disclosure No.

114: Preoperatory and Postoperatory Nutritional Repletion aiming at Intestinal Rehabilitation: A 5-year Prospective Protocol for Large Retroperitoneal Malignant Tumors

114: Preoperatory and Postoperatory Nutritional Repletion aiming at Intestinal Rehabilitation: A 5-year Prospective Protocol for Large Retroperitoneal Malignant Tumors

How I do it: using a hammock mesh in the reconstruction of inguinal ligament during a wide en-bloc resection of a groin mesenchymal tumor.

In case of soft tissue sarcomas (STS), an en-bloc resection with safe margins is recommended. To ensure safe removal without tumor rupture, STS of the groin area, retroperitoneal or pelvic mesenchymal tumors may require incision or resection of the inguinal ligament. Solid reconstruction is mandatory to prevent early and late postoperative femoral hernias. We present here a new technique of inguinal ligament reconstruction. Between September 2020 and September 2022, patients undergoing incision and/or resection of inguinal ligaments during a wide en-bloc resection of STS of the groin area in the Department of General Surgery in Strasbourg were included. All patients had an inguinal ligament reconstruction with biosynthetic slowly resorbable mesh shaped as a hammock, pre- or intraperitoneally, associated or not with loco-regional pedicled muscular flaps. A total of 7 hammock mesh reconstructions were performed. One or several flaps were necessary in 57% of cases (4 patients): either for inguinal ligament reconstruction only (n = 1), for recovering of femoral vessels (n = 1), and for both ligament reconstruction and defect covering (n = 2). The major morbidity rate was 14.3% (n = 1), related to a thigh surgical site infection due to sartorius flap infarction. After a median follow-up of 17.8months (range 7-31), there was neither early nor late occurrence of post-operative femoral hernia. This is a new surgical tool for inguinal ligament reconstruction with the implementation of a biosynthetic slowly resorbable mesh shaped as a hammock, which should be compared to other techniques.

Primary retroperitoneal squamous cell carcinoma: a literature review.

Retroperitoneal squamous cell carcinoma is an extremely rare histological variant of retroperitoneal tumors. The exact etiology and origin of the same is still unknown. To date, only a few case reports have been published in the literature. Due to rarity, standard treatment protocol is not available. The article aims to review the literature and treatment options available for this uncommon entity, based on available data. We searched the databases like PubMed, PubMed Central, Scopus, and Google Scholar with the keywords "Squamous cell carcinoma" and "retroperitoneal tumors". Peer-reviewed and recent articles were screened. Seven relevant articles comprising 14 cases were found. Due to the small number of reports, tabulation of treatment details and outcome was done. Like the sarcoma variant, these tumors also present with a large mass in the abdomen and abdominal discomfort. Association with human papillomavirus appears to be the most common factor that gives rise to squamous histology. Retroperitoneal SCC is an uncommonly diagnosed entity. Although no specific treatment guidelines exist for this uncommon malignancy; surgery followed by adjuvant or definitive radiotherapy with concurrent chemotherapy (in inoperable cases) seems a feasible option. Multicentre trials should be conducted for establishing definitive treatment strategies for this ailment.

Integrated Neurosurgical Management of Retroperitoneal Benign Nerve Sheath Tumors

Peripheral nerve sheath tumors (PNST) of the retroperitoneum are rare and are often treated by general surgeons dealing with retroperitoneal cancers. However, resection without the correct microsurgical technique can cause permanent neurological deficits and pain. Here, we discuss our interdisciplinary approach based on the integration of expertise from neurosurgery and abdominal surgery, allowing for both safe exposure and nerve-sparing microsurgical resection of these lesions. We present a series of 15 patients who underwent resection of benign retroperitoneal or pelvic PNST at our institution. The mean age of patients was 48.4 years; 67% were female. Tumors were 14 schwannomas and 1 neurofibroma. Eight patients (53%) reported neurologic symptoms preoperatively. The rate of complete resection was 87% (n = 13); all symptomatic patients showed improvement of their preoperative symptoms. There were no postoperative motor deficits; one patient (7%) developed a permanent sensory deficit. At a mean postoperative follow-up of 31 months, we observed no recurrences. To our best knowledge, this is the second-largest series of benign retroperitoneal PNST consistently managed with microsurgical techniques. Our experience confirms that interdisciplinary management allows for safe treatment of these tumors with good neurological and oncological outcomes.

68 Ga-FAPI-04 PET/MRI in a Case of Tuberous Sclerosis Complex With Extrarenal Retroperitoneal Angiomyolipoma.

Extrarenal retroperitoneal angiomyolipomas are rare benign tumors that may mimic other benign or malignant retroperitoneal tumors. We describe 68 Ga-FAPI-04 PET/MRI findings in a case of tuberous sclerosis complex with an extrarenal retroperitoneal angiomyolipoma and multiple angiomyolipomas involving bilateral kidneys. The extrarenal retroperitoneal angiomyolipoma and most of the renal angiomyolipomas were 68 Ga-FAPI-04-avid. One left renal angiomyolipoma with extensive hemorrhage and fibrosis had no significant 68 Ga-FAPI-04 uptake. Angiomyolipoma should be included in the differential diagnosis of FAPI-avid renal or extrarenal retroperitoneal lesions.