Management of benign retroperitoneal schwannomas: a single-center experience

Retroperitoneal pelvic schwannoma: A rare case report and review of the literature

Schwannoma, typically a non-cancerous tumor originating from Schwann cells, seldom occurs in the retroperitoneal area. Its clinical manifestation varies, often remaining asymptomatic for an extended period until it enlarges, exerting pressure on neighboring organs. This article presents a unique instance of retroperitoneal pelvic schwannoma in a 75-year-old woman, initially presenting with unusual lower back discomfort. Imaging was used to characterize the tumor, and anatomopathological examination established the preoperative diagnosis of pelvic schwannoma and its benign nature. The clinical, imaging, and anatomopathological aspects of this pelvic schwannoma case are elucidated herein.

Concomitant treatment of ureteral calculi and ipsilateral pelvic sciatic nerve schwannoma with transperitoneal laparoscopic approach: A case report

BACKGROUND

Schwannomas are rare peripheral neural myelin sheath tumors that originate from Schwann cells. Of the different types of schwannomas, pelvic sciatic nerve schwannoma is extremely rare. Definite preoperative diagnosis of pelvic schwannomas is difficult, and surgical resection is the gold standard for its definite diagnosis and treatment.

CASE SUMMARY

We present a case of pelvic schwannoma arising from the sciatic nerve that was detected in a 40-year-old man who underwent computed tomography for intermittent right lower back pain caused exclusively by a right ureteral calculus. Subsequently, successful transperitoneal laparoscopic surgery was performed for the intact removal of the stone and en bloc resection of the schwannoma. The total operative time was 125 min, and the estimated blood loss was inconspicuous. The surgical procedure was uneventful. The patient was discharged on postoperative day 5 with the simultaneous removal of the urinary catheter. However, the patient presented with motor and sensory disorders of the right lower limb, caused by partial damage to the right sciatic nerve. No tumor recurrence was observed at the postoperative appointment.

CONCLUSION

Histopathological examination of the specimen confirmed the diagnosis of a schwannoma. Thus, laparoscopic surgery is safe and feasible for concomitant extirpation of pelvic schwannomas and other pelvic and abdominal diseases that require surgical treatment.

Preoperative differentiation of mediastinum and retroperitoneum ganglioneuroma from schwannoma with clinical data and enhanced CT: developing a multivariable prediction model

AIM

To develop a multivariable prediction model for preoperative differentiation of ganglioneuroma (GN) from schwannoma in mediastinum and retroperitoneum based on clinical data and enhanced computed tomography (CT).

MATERIALS AND METHODS

This was a retrospective diagnostic study. Patients diagnosed with mediastinum or retroperitoneal GN or schwannoma at Zhongshan Hospital between July 2006 and March 2022 were divided into a training cohort and a validation cohort at a ratio of 7:3. Clinical information and CT features were collected. Histopathology was the reference standard for diagnosis. The model was developed using binary logistic regression. The predictive performance of the model was assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA).

RESULTS

A total of 105 patients (47 men and 58 women; mean age of 41 ± 15 years) were enrolled. There were significant differences in symptoms (p=0.006), location (p=0.008), ratio of the craniocaudal diameter (CC) to the major axis on axial images (CC/M; p=0.025), ratio of the CC to the diameter on axial images (CC/D; p<0.001), density homogeneity (p=0.001), enhancement homogeneity (p<0.001), enhancement degree (p<0.001), venous phase CT attenuation value (V; p=0.011), and blood vessels changes (p=0.045) between GN and schwannoma. The area under the ROC curve (AUC) and accuracy in the validation cohort were 0.841 (95% confidence interval [CI] 0.672, 1.000) and 0.839 (95% CI: 0.674, 0.929), respectively. Calibration curves and DCA showed that the model was beneficial for patients.

CONCLUSION

The multivariable prediction model exhibited good predictive performance and may facilitate preoperative planning.

Imaging in gynecological disease (26): clinical and ultrasound characteristics of benign retroperitoneal pelvic peripheral-nerve-sheath tumors

OBJECTIVE

To describe the clinical and sonographic characteristics of benign, retroperitoneal, pelvic peripheral-nerve-sheath tumors (PNSTs).

METHODS

This was a retrospective study of patients with a benign, retroperitoneal, pelvic PNST who had undergone preoperative ultrasound examination at a single gynecologic oncology center between 1 January 2018 and 31 August 2022. All ultrasound images, videoclips and final histological specimens of benign PNSTs were reviewed side-by-side in order to: describe the ultrasound appearance of the tumors, using the terminology of the International Ovarian Tumor Analysis (IOTA), Morphological Uterus Sonographic Assessment (MUSA) and Vulvar International Tumor Analysis (VITA) groups, following a predefined ultrasound assessment form; describe their origin in relation to nerves and pelvic anatomy; and assess the association between their ultrasound features and histotopography. A review of the literature reporting benign, retroperitoneal, pelvic PNSTs with preoperative ultrasound examination was performed.

RESULTS

Five women (mean age, 53 years) with a benign, retroperitoneal, pelvic PNST were identified, four with a schwannoma and one with a neurofibroma, of which all were sporadic and solitary. All patients had good-quality ultrasound images and videoclips and final biopsy of surgically excised tumors, except one patient managed conservatively who had only a core needle biopsy. In all cases, the findings were incidental. The five PNSTs ranged in maximum diameter from 31 to 50 mm. All five PNSTs were solid, moderately vascular tumors, with non-uniform echogenicity, well-circumscribed by hyperechogenic epineurium and with no acoustic shadowing. Most of the masses were round (n = 4 (80%)), and contained small, irregular, anechoic, cystic areas (n = 3 (60%)) and hyperechogenic foci (n = 5 (100%)). In the woman with a schwannoma in whom surgery was not performed, follow-up over a 3-year period showed minimal growth (1.5 mm/year) of the mass. We also summarize the findings of 47 cases of benign retroperitoneal schwannoma and neurofibroma identified in a literature search.

CONCLUSIONS

On ultrasound examination, no imaging characteristics differentiate reliably between benign schwannomas and neurofibromas. Moreover, benign PNSTs show some similar features to malignant retroperitoneal tumors. They are solid lesions with intralesional blood vessels and show degenerative changes such as cystic areas and hyperechogenic foci. Therefore, ultrasound-guided biopsy may play a pivotal role in their diagnosis. If confirmed to be benign PNSTs, these tumors can be managed conservatively, with ultrasound surveillance. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Surgical management of sporadic and schwannomatosis-associated pelvic schwannomas

Pelvic schwannomas are rare tumors that may occur either sporadically or in the context of schwannomatosis. We retrospectively reviewed the charts of patients harboring a pelvic schwannoma under conservative management or operated at our reference center between 2016 and 2023. All patients were operated by a multidisciplinary team, combining a vascular surgeon and a neurosurgeon. Twenty-four patients harboring 33 pelvic tumors were included in the cohort, including 12 patients with sporadic lesions, 2 patients with NF2-related schwannomatosis, and 10 patients with NF2-independent schwannomatosis. Multi-nodular tumors were more frequent in schwannomatosis compared to sporadic cases (p = 0.005). The mean age at diagnosis was 41 years old. Schwannomas were located on branches of the sciatic nerve (23/33, 70%), the femoral nerve (6/33, 18%), and the obturator nerve (4/33, 12%). Over the course of the study, 16 patients were operated, including 11 sporadic cases. The indication for surgery was pain (12/16, 75%) or tumor growth (4/16, 25%). Complete resection was achieved in 14 of 16 patients (87%). The mean post-operative follow-up was 37 months (range: 2-168 months). At last-follow-up, complete pain relief was achieved in all 12 patients with pre-operative pain. Post-operative morbidity included 3 long-term localized numbness and one MRC class 4 motor deficit in a multi-nodular tumor in a schwannomatosis patient. Despite its limited size, our series suggests that nerve-sparing resection of pelvic schwannomas offers satisfying rates of functional outcome both in sporadic and schwannomatosis cases, except for multi-nodular tumors.

Preoperative contrast-enhanced CT-based radiomics nomogram for differentiating benign and malignant primary retroperitoneal tumors

OBJECTIVES

This study evaluated the ability of a preoperative contrast-enhanced CT (CECT)-based radiomics nomogram to differentiate benign and malignant primary retroperitoneal tumors (PRT).

METHODS

Images and data from 340 patients with pathologically confirmed PRT were randomly placed into training (n = 239) and validation sets (n = 101). Two radiologists independently analyzed all CT images and made measurements. Key characteristics were identified through least absolute shrinkage selection combined with four machine-learning classifiers (support vector machine, generalized linear model, random forest, and artificial neural network back propagation) to create a radiomics signature. Demographic data and CECT characteristics were analyzed to formulate a clinico-radiological model. Independent clinical variables were merged with the best-performing radiomics signature to develop a radiomics nomogram. The discrimination capacity and clinical value of three models were quantified by the area under the receiver operating characteristics (AUC), accuracy, and decision curve analysis.

RESULTS

The radiomics nomogram was able to consistently differentiate between benign and malignant PRT in the training and validation datasets, with AUCs of 0.923 and 0.907, respectively. Decision curve analysis manifested that the nomogram achieved higher clinical net benefits than did separate use of the radiomics signature and clinico-radiological model.

CONCLUSIONS

The preoperative nomogram is valuable for differentiating between benign and malignant PRT; it can also aid in treatment planning.

KEY POINTS

• A noninvasive and accurate preoperative determination of benign and malignant PRT is crucial to identifying suitable treatments and predicting disease prognosis. • Associating the radiomics signature with clinical factors facilitates differentiation of malignant from benign PRT with improved diagnostic efficacy (AUC) and accuracy from 0.772 to 0.907 and from 0.723 to 0.842, respectively, compared with the clinico-radiological model alone. • For some PRT with anatomically special locations and when biopsy is extremely difficult and risky, a radiomics nomogram may provide a promising preoperative alternative for distinguishing benignity and malignancy.

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.

Clinical characteristics and prognosis of cystic degeneration in retroperitoneal schwannoma: A retrospective study of 79 patients

BACKGROUND AND PURPOSE

Diagnosis of retroperitoneal schwannoma (RS), especially cystic RS, is frequently missed or delayed owing to its rarity, location, nonspecific symptoms, and similarities with other tumors on various imaging modalities. This study aimed to determine associations between clinical, radiological, and histopathologic features and outcome.

MATERIALS AND METHODS

Seventy-nine patients with pathologically confirmed RS who underwent tumor resection between June 2010 and June 2020 were retrospectively reviewed and analyzed. Patients were stratified into three groups according to degree of tumoral cystic degeneration.

RESULTS

Cystic degeneration was significantly associated with multiple foci (p = 0.025), calcification (p = 0.012), and hemorrhage (p = 0.000), but not size (p = 0.08), high Ki-67 (p = 0.094), malignancy (p = 0.115; prevalence of cystic degeneration in the benign and malignant groups were 53.9% vs 100%), rough margin (p = 0.162), or irregular shape (p = 0.369). Malignant RS was significantly associated with multiple lymph nodes enlargement (p = 0.034). Tumor size, margins, shape, or/and multiplicity did not significantly differ between benign and malignant tumors. No recurrence occurred in patients with benign RS (mean follow-up, 45 months). All malignant tumors recurred; mean time to recurrence was 11.4 months (mean follow-up, 33 months).

CONCLUSION

Since RS is misdiagnosed mostly as malignancy and diagnosis is often delayed, a suspicion is necessary for diagnosis when atypical features are present. In RS, cystic degeneration was not associated with tumor size, Ki-67, or malignancy; however, it was significantly associated with multiple foci, calcification, and hemorrhage. Cystic degeneration and related factors are useful for the diagnosis of RS. Malignant RS should be considered when a mass involves multiple lymph nodes. Margins, morphology, and size are not associated with malignancy. Pathological tumor type, tumor location, and adjacent anatomic structures are associated with outcome.

An unusual histological finding following myomectomy

Ancient schwannomas are benign tumours arising from the neural sheath of peripheral, cranial and autonomic nerves. They are commonly situated in the inner ear and spine with pelvic manifestations being rare. We present the case of a 30-year-old patient, who presented with an abdominal mass. MRI imaging suggested a broad ligament fibroid and open surgery was undertaken to remove it. Subsequent histology confirmed an ancient schwannoma. This case report details the rarity of such a condition and the need for a high index of suspicion as well as outlining management options and surveillance.

Two giant connected retroperitoneal schwannomas: a rare case report

Schwannoma is a type of tumor originating from Schwann cells of peripheral nerves. In this study, we report a rare case of two giant connected retroperitoneal schwannomas. The patient presented to our department with a 1-day history of abdominal pain and without other symptoms. There were no abnormalities in the patient’s tumor markers. Abdominal plain computed tomography (CT) revealed two (combined) retroperitoneal masses appearing as soft tissue-density shadows with uneven internal density, cystic low-density shadows, and patchy calcification shadows. The larger mass measured approximately 12.0 cm × 12.3 cm in size. The tumors were completely excised by a reasonable surgical approach while the surrounding organs closely related to the tumor were preserved. Postoperative pathology confirmed that the tumors were benign schwannomas. In the 18-month follow-up, the patient had no recurrences and was asymptomatic. We summarize the diagnosis and treatment of two rare combined giant retroperitoneal schwannomas in a single patient. Laparotomy for the management of retroperitoneal giant schwannomas may be safe and effective.

Rare retroperitoneal conditions that mimic uterine myoma

The most frequent tumoral condition of the uterus is represented by uterine myoma. The diagnosis, in most cases, is established by clinical examination and ultrasound scan. Nevertheless, there are rare cases, in which the surgical findings reveal a retroperitoneal tumor instead of a uterine myoma. These could be represented by schwannomas or Castleman disease. The schwannomas are rarely malignant and arise from the Schwann cells of nerve fibers. These tumors are frequently found at the level of the head, neck and mediastinum and rarely in the pelvis. Generally, schwannomas localized at retroperitoneal level are asymptomatic and with a very slow growth rate. The treatment consists in complete surgical resection. The recurrence rate is low and, generally, the prognosis is good. The Castleman disease is considered a rare entity, but it should be always taken into consideration when it comes to a differential diagnosis in a young patient who presents a retroperitoneal mass at imagery exams. The condition affects the lymphatic system and is characterized by a hyperplasia of the lymph nodes, sometimes associated with herpes virus infection. The clinical picture is often non-specific; the pain may be the only symptom. The imaging methods are not always conclusive for the final positive diagnosis and the histopathological examination is always necessary. Pelvic Castleman disease can be misdiagnosed as myoma or an adnexal tumor. In this article, we review the present knowledge regarding the pathogenesis, pathology and management of these rare retroperitoneal tumors. Both conditions, when located in pelvis must be taken into consideration in the differential diagnosis of uterine myomas, especially in the pedunculated form.

Diagnostic Dilemma of Retroperitoneal Schwannomas Encountered in a Specialized Gynecology Hospital

BACKGROUND

This study analyzed the potential diagnosis and therapeutic challenges of retroperitoneal schwannoma (RSs) in a specialized gynecology hospital.

METHODS AND MATERIALS

A retrospective review was performed in our hospital from 2000 to 2018. A literature search of RSs was conducted using PubMed database.

RESULTS

45 patients were identified (22 from our hospital and 23 from the literature review). The majority of patients presented asymptomatic (22/45). Among them, 25 cases were misdiagnosed as adnexal cysts, 13 uterine fibroids, 1 ovarian malignancy and 6 pelvic masses. Intraoperative exploration revealed that the masses were located in the retroperitoneal space. The median diameter was 6.2 cm (range 3.0-9.8 cm) in our hospital compared with 9.3 cm (6-15 cm) in literature review. Complete resection was performed in 37 patients and subtotal resection in 8 patients. The pathological results confirmed the diagnosis of benign schwannoma and no recurrence was found in the follow-up data.

CONCLUSION

The preoperative diagnosis of RSs is difficult to make because of its nonspecific characteristics. In a specialized gynecology hospital, it is more important to differentiate the benign and malignant of mass before surgery. Surgical complete resection of tumor is recommended and recurrence is unusual after complete resection.

Retroperitoneal Schwannoma: Two Rare Case Reports

Schwannomas are neuroectodermal tumors that rarely occur in the retroperitoneal space. We report two cases of patients who presented with abdominal pain. Radiological findings revealed a retroperitoneal mass in both cases. Both patients underwent complete surgical excision with an uneventful postoperative course. The histopathological study confirmed the nature of schwannoma. Complete surgical excision remains the gold standard for the management of these tumors. The preoperative diagnosis is usually difficult; however, the definitive diagnosis is made upon histopathological examination.

Retroperitoneal tumors: Review of diagnosis and management

Retroperitoneal tumors are extremely rare tumors occurring in the retroperitoneum. Retroperitoneal tumors are divided into benign tumors and malignant tumors, including retroperitoneal sarcoma. Approximately 70-80% of primary retroperitoneal soft-tissue tumors are malignant; however, these only account for 0.1-0.2% of all malignancies. Retroperitoneal sarcoma is an orphan malignant disease with a low incidence. The information on benign retroperitoneal tumors is limited. The American Joint Committee on Cancer/TNM classification updated to the 8th edition in 2017. In 2010, three new drugs for soft tissue sarcoma were approved based on the results of phase III trials, but the histological subtypes of the patients enrolled in the trials of each drug differed. Recently, in addition to surgery for retroperitoneal sarcoma, the effectiveness of perioperative radiation therapy has become interesting. For malignant retroperitoneal tumors and retroperitoneal sarcoma, survival improvement and locoregional recurrence prevention can be undertaken by carrying out surgery to secure negative margins with wide and combined resection of some adjacent organs, and cooperation with a trained medical team comprising of radiologists, pathologists and medical oncologists in centralized hospitals. Some clinical trials aimed at further improving treatment results by adding preoperative chemotherapy and radiation therapy based on histological confirmation using a correct needle biopsy are in progress. In recent years, molecular profiling has been used to select eligible patients for chemotherapy. In the future, precision medicine with next-generation sequencing technology will be expected among the diverse and potential future treatments for retroperitoneal sarcoma. In this review, we summarized the current state of retroperitoneal tumors and retroperitoneal sarcoma.

Retroperitoneal schwannoma sandwiched between abdominal aorta and inferior vena cava. A case report

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Retroperitoneal schwannomas in the abdominal cavity are rare and pose difficulty in preoperative diagnosis and management.

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Imaging modalities are usually not sufficient to conclude a diagnosis.

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EUS-FNA is useful to confirm preoperative diagnosis.

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In EUS-FNA, diagnosis can be accurate if the tumor size is small and tumor is devoid of intratumoral degenerations.

Introduction

Schwannomas are tumors that originate from the Schwann cells present in the nerve sheath of peripheral nerves. They are commonly seen in cephalocervical areas. Schwannomas in the abdominal cavity are rare. Here, we discuss a case of retroperitoneal schwannoma lying dorsal to pancreas with critical relations to surrounding vessels.

Presentation of case

A 74 years old asymptomatic male was found with elevated amylase level on his routine blood examination. MR imaging revealed retroperitoneal mass of size 21*18*24 mm. EUS-FNA confirmed retroperitoneal schwannoma. The patient had co-morbid renal disease and was on hemodialysis. During the latest follow up, the tumor was 41*37*41 mm in size located dorsal to the confluence of right renal vein and inferior vena cava. The tumor was in contact with inferior vena cava, horizontal part of duodenum, right renal artery, right kidney, and adrenal gland. The patient underwent laparotomy and the tumor was extract with intact capsule. There were no post-operative complications.

Discussion

Pre-operative diagnosis in retroperitoneal schwannomas is challenging because imaging features are usually non-specific, and biopsy is the only diagnostic technique. EUS-FNA, which has low diagnostic accuracy, is useful in pre-operative diagnosis of small tumors devoid of intra-tumoral degeneration.

Conclusion

Retroperitoneal schwannoma is a rare entity. Preoperative diagnosis and curative resection are technically difficult. Care should be given during preoperative investigations and surgical resection of the tumor. EUS-FNA can be a useful diagnostic tool.

Giant Pelvic Schwannoma: Case Report and Review of the Literature

INTRODUCTION

Pelvic schwannomas are rare, mostly benign tumors. They are usually asymptomatic until their massive growth compresses adjacent organs. We describe the case of a 53-year-old man with a pelvic schwannoma who initially complained of constipation and urinary retention.

AREAS COVERED

We analyzed the clinical presentation, histopathology, diagnostic imaging tools, and the treatment options for pelvic schwannomas, compared with the few other cases reported in the literature.

EXPERT COMMENTARY

Pelvic schwannomas are masses that can grow to considerable size, producing symptoms over time. Due to their size and localization, surgery, although difficult, is the only available treatment.

Interdisciplinary approach allows minimally invasive, nerve-sparing removal of retroperitoneal peripheral nerve sheath tumors

Purpose

En bloc resection of retroperitoneal peripheral nerve sheath tumors (PNST) is advocated by a variety of surgical disciplines. Yet, microsurgical, nerve-sparing tumor resection might be better suited to improve symptoms and maintain neurological function, especially in cases where patients present with preoperative neurological deficits. However, neurosurgeons, versed in nerve-sparing techniques to remove PNST, are generally unfamiliar with the visceral approaches to retroperitoneal PNST.

Methods

We retrospectively evaluate a series of 16 patients suffering from retroperitoneal PNST. Patients were treated by a unique interdisciplinary approach, combining the visceral surgeon’s skills to navigate the complex anatomy of the retroperitoneal space and the neurosurgeon’s familiarity with microsurgical, nerve-sparing tumor removal. Specifically, we assess whether our interdisciplinary approach is suited to improve preoperative symptoms and maintain neurological function and study whether oncological outcome, surgical morbidity, and operative times are comparable to those reported for “classical” retroperitoneal PNST resection. In addition, we study two cases of suspected PNST that were diagnosed as malignant peripheral nerve sheath tumors (MPNST) after surgery.

Results

Total macroscopic tumor resection was achieved in 14/16 PNST patients. Mean intraoperative blood loss was 680.6 ml (95% CI, 194.3–1167.0 ml) and mean operative time was 162.5 min (95% CI, 121.6–203.4 min). We did not record any major postoperative surgical or neurological complications. A total of 8/11 patients with preoperative pain symptoms reported long-lasting improvement of their symptoms. In terms of oncological outcome, all patients that had been subjected to total tumor removal and for whom follow-up was available, were tumor-free after a mean follow-up of 761.9 days (95% CI, 97.6–1426.0 days). One of the two MPNST patients, who presented with tumor progress 15 months after initial surgery, was subjected to radical re-resection.

Conclusions

Interdisciplinary, nerve-sparing removal of retroperitoneal PNST is well suited to improve preoperative symptoms and maintain neurological function, while achieving an oncological outcome and a surgical morbidity similar to previously reported results for radical retroperitoneal PNST resection. Radical re-resection was feasible in a patient with post hoc MPNST diagnosis.

Intercontinental collaborative experience with abdominal, retroperitoneal and pelvic schwannomas

Background

Schwannomas are rare tumours that pose a significant management challenge in the abdomen, retroperitoneum and pelvis. No data are available to inform management strategy.

Methods

A collaborative international cohort study, across specialist sarcoma units, was conducted to include adults presenting between 2000 and 2017 with histopathologically confirmed schwannomas within the abdomen, retroperitoneum or pelvis.

Results

Of 485 patients across 12 centres, 38 (7·8 per cent) were discharged without follow-up, 199 (41·0 per cent) underwent early resection and 248 (51·1 per cent) had radiological monitoring. Of these 248 patients, 96 (38·7 per cent) eventually had surgery, giving an overall resection rate of 60·8 per cent (295 of 485). At baseline, median tumour volume was 90·1 (i.q.r. 26·5–262·0) cm3. The estimated growth rate was 10·5 (95 per cent c.i. 9·4 to 11·6) per cent per year, and was consistent in the short term (within 2 years of diagnosis) and long term (beyond 2 years) (ρ = 0·405, P = 0·021). A decision to operate was more common in symptomatic patients (P &lt; 0·001) and for rapidly growing tumours (growth rate more than 20 per cent per year) (P = 0·025). R0/R1 resection was achieved in 91·6 per cent of patients (263 of 287). Kaplan–Meier long-term recurrence rates after R0/R1 resection were 2·3 and 6·7 per cent at 3 and 5 years respectively.

Conclusion

Specific recommendations include: indications for early surgery, prediction of growth from radiological monitoring, promotion of selective submacroscopic resection and cessation of postoperative imaging surveillance.

Retroperitoneal schwannoma preoperatively diagnosed as liver metastasis from colon cancer: A case report

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Retroperitoneal schwannomas are very rare and difficult to make a definite diagnosis.

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This is the first report of surgery for colon cancer and retroperitoneal schwannoma performed simultaneously.

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Although liver lesions accompanied by advanced malignant tumor should be firstly considered as liver metastasis, other rare tumors are also occasionally seen.

Background

Retroperitoneal schwannomas are rare.

Case presentation

We here report a case of 64-year-old woman who was referred to her local hospital for abdominal pain and found to have a palpable tumor. Computed tomography (CT) and colonoscopy revealed a combination of liver and colon lesions and colon cancer with a large liver metastasis was suspected. After neoadjuvant chemotherapy had proved ineffective for her presumed liver metastasis, the patient was referred to our hospital where we performed a simultaneous right hemicolectomy and extended left hepatic lobectomy. The pathological diagnoses were a colonic adenocarcinoma and retroperitoneal schwannoma immediately adjacent to the liver.

Conclusions

Although liver metastasis should be the first provisional diagnosis in patients with advanced colon cancer, retroperitoneal schwannoma should also be suspected in the differential diagnosis of possible liver lesions.

The natural history of incidental retroperitoneal schwannomas

The natural history of asymptomatic retroperitoneal schwannomas is poorly understood. This study aimed at investigating the natural history of incidental retroperitoneal schwannomas. The medical charts and imaging studies of 22 asymptomatic patients under observation for at least 12 months for retroperitoneal schwannomas were reviewed. The duration of follow-up ranged between 13 and 176 months (mean 48 months). In the 22 patients managed by the “wait and see” approach, the average tumor size at initial presentation was 51 mm, which increased to 57 mm at final follow-up. During the final follow-up, 2 patients required surgical treatment for tumor enlargement, while the remaining patients remained asymptomatic without surgery. The average growth rate of the tumors was 1.9 mm/year (range: -1.9 to 8.7 mm/year). The majority of asymptomatic retroperitoneal schwannomas demonstrate minimal growth and may be suitable for management with the “wait and see” approach.

Clinicopathological variables of sporadic schwannomas of peripheral nerve in 291 patients and expression of biologically relevant markers

OBJECTIVE While sporadic peripheral schwannomas (SPSs) are generally well treated with surgery, their biology is not well understood. Consequently, treatment options are limited. The aim of this study was to provide a comprehensive description of SPS. The authors describe clinicopathological features and treatment outcomes of patients harboring these tumors, and they assess expression of biomarkers using a clinically annotated tissue microarray. Together, these data give new insight into the biology and management of SPS. METHODS Patients presenting with a primary SPS between 1993 and 2011 (n = 291) were selected from an institutional registry to construct a clinical database. All patients underwent follow-up, and short- and long-term outcomes were assessed. Expression of relevant biomarkers was assessed using a new tissue microarray (n = 121). RESULTS SPSs were generally large (mean 5.5 cm) and frequently painful at presentation (55%). Most patients were treated with surgery (80%), the majority of whom experienced complete resolution (52%) or improvement (18%) of their symptoms. Tumors that were completely resected (85%) did not recur. Some patients experienced short-term (16%) and long-term (4%) complications postoperatively. Schwannomas expressed higher levels of platelet-derived growth factor receptor-β (2.1) than malignant peripheral nerve sheath tumors (MPNSTs) (1.5, p = 0.004) and neurofibromas (1.33, p = 0.007). Expression of human epidermal growth factor receptor-2 was greater in SPSs (0.91) than in MPNSTs (0.33, p = 0.002) and neurofibromas (0.33, p = 0.026). Epidermal growth factor receptor was expressed in far fewer SPS cells (10%) than in MPNSTs (58%, p < 0.0001) or neurofibromas (37%, p = 0.007). SPSs more frequently expressed cytoplasmic survivin (66% of tumor cells) than normal nerve (46% of cells), but SPS expressed nuclear survivin in fewer tumor cells than in MPNSTs (24% and 50%, respectively; p = 0.018). CONCLUSIONS Complete resection is curative for SPS. Left untreated, however, these tumors can cause significant morbidity, and not all patients are candidates for resection. SPSs express a pattern of biomarkers consistent with the dysregulation of the tumor suppressor merlin observed in neurofibromatosis Type 2-associated schwannomas, suggesting a shared etiology. This SPS pattern is distinct from that of other tumors of the peripheral nerve sheath.

Retroperitoneal schwannoma misdiagnosed as an ovarian malignancy

A 55-year-old woman presented to the hospital with abdominal discomfort over 3 months. Contrast-enhanced abdominal CT showed a 10×9×6.5 cm sized well-defined solid-cystic enhancing mass in the right pelvic cavity. Under general anaesthesia, exploratory laparotomy was performed on suspicion of ovarian malignancy. Pathological examination revealed a retroperitoneal schwannoma with highly ordered cellular component (Antoni A) and hypocellularity with predominantly loose myxoid component (Antoni B). On immunohistochemical staining, the sample showed typically positive result for S-100 in the cytoplasm of the tumour cells. Schwannomas are consisting only of Schwann cells and are most often non-malignant tumors. It is relatively slow growing and usually located in the head, neck and the extremities. Schwannomas are quite rare in the retroperitoneal region. The diagnosis of retroperitoneal schwannomas is often delayed and misdiagnosed as an adnexal tumour, especially locating in the pelvic cavity. Surgical complete resection of tumour is the treatment of choice and recurrence is unusual after complete resection.

Robotic resection of an obturator schwannoma with preservation of normal nerve fascicles and function

An asymptomatic pelvic tumor was incidentally found in a 27-year-old man. A CT-guided needle biopsy with a pathologic examination confirmed the diagnosis of a benign schwannoma. We describe the complete robotic resection with the conservation of normal fascicles. The postoperative course was uneventful. No neurological deficit occurred, and the electromyogram was normal 6 weeks and 7 months later.

RETROPERITONEAL SCHWANNOMA (CLINICAL CASE)

Schwannoma - a tumor growing from Schwann cells of the peripheral nerve sheath. Retroperitoneal schwannoma is a rare tumor accounting for approximately 1 to 5% of all retroperitoneal neoplasms. Retroperitoneal localization occurs for a total in 0.75-2.6% of cases, often they localize in the extremi- ties, the head and neck. Despite the significant progress made currently in the field of instrumental studies for non-organ retroperitoneal tumors, diagnosis and differential diagnosis remain a complex problem requiring further study. Presented clinical case illustrates difficulties in the diagnosis of retro- peritoneal schwannoma. Precise preoperative determination of the tumor relationship with all the nearby organs and vessels according to the different methods of ray diagnostics gives an opportunity to define the tactics of treatment.

Lateral access to paravertebral tumors

Traditional transabdominal and retroperitoneal approaches for paravertebral tumors can be associated with injury to the viscera and lumbar plexus. The authors provide a technical description of a known approach with a new application for the resection of paraspinal tumors using both open and minimally invasive transpsoas techniques and report on 2 illustrative cases. In both cases, gross-total resection of the tumor was achieved and the patients experienced resolution of their presenting neurological symptoms, although one of the patients required 2 extra days of hospitalization due to an asymptomatic retroperitoneal hematoma, which was conservatively managed.

The authors conclude that the lateral transpsoas approach is a safe approach for paravertebral tumors and may not require an access surgeon.

Surgical treatment of a retroperitoneal benign tumor surrounding important blood vessels by fractionated resection: A case report and review of the literature

Retroperitoneal tumors are lesions with diverse pathological subtypes that originate from the retroperitoneal space; ~40% of these tumors are benign. Due to such lesions often surrounding and associating with vital abdominal blood vessels, a complete surgical resection is difficult. The current study presents a novel surgical approach, known as fractionation, through which a benign retroperitoneal tumor surrounding important abdominal blood vessels was completely resected. A 21-year-old man was admitted to The First Affiliated Hospital of Chongqing Medical University (Chongqing, China), presenting with a ~7.5×7.2-cm tumor that was located in the retroperitoneal pancreatic head region and the first hepatic hilum. The tumor completely surrounded the celiac axis and the splenic, common hepatic and superior mesenteric arteries, and was closely associated with the abdominal aorta and the portal, splenic, superior mesenteric and left renal veins. A pre-operative computed tomography scan and intraoperative frozen biopsy indicated that the lesion was a benign tumor. A fractionation approach was subsequently adopted, with fractionation of the lesion being performed according to the location of the tumor itself and the direction of the surrounding abdominal blood vessels. In this manner, a complete tumor resection was conducted. Post-operative pathological examination confirmed the diagnosis of a retroperitoneal ganglioneuroma. The patient was followed up for a year and a half, with no evidence of tumor recurrence. In the present case, a fractionation approach for the complete resection of the retroperitoneal benign tumor achieved a positive outcome and demonstrated the feasibility of the technique.

CT and MR imaging of retroperitoneal schwannoma

The purpose of this presentation is to allow the radiologist to discuss the diagnosis of retroperitoneal schwannoma, involving mostly a fortuitous discovery and a misleading clinical presentation. We present 4 cases of retroperitoneal schwannoma, two having benefited from a surgery and two others of a therapeutic abstention. The retropritoneal localization and the imaging are good indicator elements of this pathology. The constant improvement of the CT and MR imaging allows a better approach of this entity also by specifying its localization and its anatomical relationships to guide the therapeutic attitude which must be remain mutidisciplinary.

Pelvic schwannoma in the right parametrium

Neurilemomas are benign usually encapsulated nerve sheath tumors derived from the Schwann cells. These tumors commonly arise from the cranial nerves as acoustic neurinomas but they are extremely rare in the pelvis and the retroperitoneal area (less than 0.5% of reported cases), unless they are combined with von Recklinghausen disease (type 1 neurofibromatosis). We report the case of a 58-year-old female with pelvic schwannoma, 6.5 × 5.5 cm in size, in the right parametrium. This is the first case reported in the literature. Based on the rarity of this tumor and in order to ensure optimum treatment and survival for our patient, we performed laparotomy with total abdominal hysterectomy and en-block tumor excision. A frozen section was taken during the surgery before complete resection of the mass, which was ambiguous. Because of the possibility of malignancy, complete excision of the mass was performed, with pelvic blunt dissection. Histological examination showed a benign neoplasm, originating from the cells of peripheral nerve sheaths; diagnosis was a schwannoma. There were degenerative areas, including cystic degeneration, hemorrhagic infiltrations, ischemic foci with pycnotic cells, and collagen replacement. Pelvic schwannomas are rare neoplasms that can be misdiagnosed. Laparoscopy is a safe and efficient option for approaching benign pelvic tumors and might offer the advantage of better visualization of structures due to the magnification in laparoscopic view, especially in narrow anatomic spaces.

Simultaneous Right Retroperitoneal Schwannoma and Left Renal Hydatid Cyst

Retroperitoneal schwannomas are quite rare tumors. Isolated renal hydatid cyst is also rare, and it forms 2–4% of hydatid disease. Because of their infrequent occurrence, nonspecific signs and symptoms, and lack of distinguishing radiologic features, we report herein a case of right retroperitoneal mass in a 26-year-old woman which was found to be benign schwannoma following a percutaneous core needle biopsy and a large cortical cyst in the lower pole of the left kidney which was diagnosed as isolated renal hydatid cyst following exploration.

Lumbar plexus schwannoma causing recurrent syncope

Retroperitoneal schwannomas are rare and present non-specifically. They usually manifest secondary to their compressive effects on adjacent structures. We describe a patient who presented with recurrent syncope resulting from a large retroperitoneal schwannoma stretching the inferior vena cava and compromising venous return. We also discuss the salient aspects of preoperative investigations leading to definitive diagnosis and surgery.

Retroperitoneal schwannoma treated with percutaneous computed tomography-guided radiofrequency ablation

Retroperitoneal schwannomas (RSs) are particularly rare tumors, and resection is the first choice for symptomatic patients. However, some RSs with anatomical complexities pose great challenges for surgeons attempting radical resection without sacrificing the nearby critical structures, and subtotal resection leads to local recurrence, especially in refractory malignant RSs. The authors have successfully applied percutaneous CT-guided radiofrequency ablation in 2 cases of RSs, with favorable long-term progression-free survival.