The natural history of incidental retroperitoneal schwannomas

Analysis of Benign Retroperitoneal Schwannomas: A Single-center Experience

BACKGROUND

 Retroperitoneal schwannomas are rare. The purpose of this study was to present our experience with the diagnosis and treatment of 67 such tumors.

METHODS

 We retrospectively analyzed 67 patients with retroperitoneal schwannoma admitted to the Peking University International Hospital from 2015 to 2021.

RESULTS

 Thirty-seven of the 67 patients had no obvious clinical symptoms. Complete excision was obtained in 62 and subtotal excision in 5 cases. In7 cases, tumor resection was combined with organ resection. The intraoperative blood loss was 300 ml (20-9,000 ml), the maximum size of the tumor was 9 cm (2.5-26 cm), and postoperative complication occurred in six cases (9.0%). Compared with abdominal retroperitoneal tumors, pelvic retroperitoneal tumors had larger tumor volume, more bleeding, higher proportion of block resection, and longer postoperative hospitalization time (p < 0.05). The residual mass progressed slowly in five patients with subtotal resection, and no obvious malignant transformation occurred.

CONCLUSION

 Complete resection of a retroperitoneal schwannoma can achieve a good long-term prognosis. Residual tumor after surgery progresses slowly and rarely become malignant. We recommend early resection after the discovery of a pelvic retroperitoneal schwannoma.

Six year natural progression of a clinically monitored retroperitoneal schwannoma: A case report

INTRODUCTION AND IMPORTANCE

Schwannomas arise from Schwann cells, which make up the neural sheath of peripheral nerves. These tumors are usually seen in the head, neck and flexor surfaces, but can arise in the retroperitoneal space on rare occasions. This case gives the unique opportunity to watch the long term progression and speed of growth of this rare tumor and the development of symptoms over time.

CASE PRESENTATION

Here, we describe the interesting case of a retroperitoneal Schwannoma discovered incidentally that was then monitored over the course of six years. After the tumor grew from 2.4 × 2.2 cm to 5.4 × 5.2 cm over this time, symptoms such as abdominal pain, nausea, constipation, increased urinary frequency, and left leg paresthesia arose, prompting for removal of the tumor. On follow-up two weeks later, the patient reported resolution of symptoms.

CLINICAL DISCUSSION

Treatment for this tumor is either immediate excision or the "watch and wait" method, as this tumor has a low rate of malignant transformation. The tumor discussed in this case had a higher rate of growth before removal when compared to other studies examining retroperitoneal Schwannoma development.

CONCLUSION

The "watch and wait" method of treatment for this benign tumor is effective, but it is important to ensure the patient is aware that the tumor will likely continue to grow. Given this, the patient should be informed of possible mass effect symptoms to monitor for.

Retroperitoneal ancient schwannoma presenting as left flank pain and moderate unilateral hydronephrosis: A case report and literature review

Key Clinical Message

Benign ancient retroperitoneal schwannomas (BARS) exhibit abdominal masses and flank pain to incidental findings at more advanced stages. Histopathological and immunohistochemical analysis is essential for confirmation of benign nature. Our patient was misdiagnosed as ureteric colic, highlighting the need to consider BARS in differential diagnosis to prevent complications like hydronephrosis.

Abstract

Ancient schwannomas are usually benign neoplasms that originate from Schwann cells of peripheral nerves. We present a novel case of a 24-year-old young male with left flank pain and nausea which was initially thought to be left ureteric colic. However, in-depth imaging and biopsy revealed a retroperitoneal mass. The definitive diagnosis was narrowed down to Benign Retroperitoneal Ancient Schwannoma (BARS) via immunohistochemistry and histopathological analysis. This often marble-shaped S100 protein-positive tumor is an under-recognized and potential cause of hydronephrosis if localized near the renal structures. In addition, the retroperitoneal location with infrarenal abdominal aortic adherence is another rare peculiarity in the present case that demands prompt diagnosis and surgical excision to avoid any cardiovascular sequelae such as hypotension and abdominal pain, as indicated by the natural history of growth of this benign tumor. Therefore, timely excision of this benign tumor prior to its further proliferation is paramount. We initially planned laparoscopic removal but adopted excision via laparotomy because of the proximity of the vital structures. The postoperative course of the patient was uneventful and subsequently the patient's presenting complaint of left abdominal flank pain greatly improved. The patient was advised to undergo follow-up computed tomography scan of kidney ureter bladder and RFT evaluation 6 months postsurgery which indicated no evidence of recurrence or iatrogenic complications. The diagnosis and management of the present case share valuable experiences for similar future cases worldwide.

[Retroperitoneal schwannoma mimicking colorectal cancer metastases: a false positive result report.]

Introduction

schwannomas are benign and common soft tissue tumors. They are usually asymptomatic and are discovered for other reasons.

Materials

we present the case of an 82-year-old male patient with a recent diagnosis of moderately differentiated adenocarcinoma of the colon and a hypermetabolic periaortic nodule as an incidental finding.

Results

percutaneous biopsy of the periaortic nodule confirmed the diagnosis of schwannoma. At one year of follow-up, growth of the schwannoma has been demonstrated. There are no signs of progression of his oncological disease.

Conclusions

schwannomas are benign tumors, rarely found in the retroperitoneum and can be sources of false-positive positron emission tomography results.

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.

Successful management of a giant retroperitoneal ancient schwannoma mimicking malignant tumors: A case report and literature review

Introduction and Importance

Schwannomas, originating from Schwann cells surrounding nerve sheaths, tend to be slow-growing. Among these, giant ancient schwannomas are remarkable for their rare occurrence and their capacity for substantial growth and regressive changes. Furthermore, the expansiveness and flexibility of the retroperitoneal space often conceal the symptoms of retroperitoneal schwannomas, leading to delayed diagnosis and allowing these tumors to grow significantly and become large and long-standing before detection.

Case Presentation

A 24-year-old man presented with left flank pain and a growing abdominal bulge in the left upper quadrant. Computed tomography scan revealed a 15×15×10 cm lytic expansile lesion. Consequently, the encapsulated mass was surgically excised and diagnosed as an ancient retroperitoneal schwannoma through histological and immunohistochemical studies.

Clinical Discussion

Comprehensive preoperative planning and a multidisciplinary strategy are imperative for the complete excision of schwannomas. These tumors can present diagnostic complexities, particularly due to nuclear atypia and pleomorphism, which might lead to misinterpretation regarding malignancy. Despite the risks associated with percutaneous biopsies, the low mitotic count is a critical diagnostic factor. Our study underscores the consensus that the definitive diagnosis should rely on postoperative histopathological findings, highlighting the importance of accurate assessment.

Conclusion

Rare giant retroperitoneal ancient schwannomas pose diagnostic challenges due to their rarity, lack of distinct symptoms, and atypical locations. This study presents a successful case and management.

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.

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.

Natural History of Brachial Plexus, Peripheral Nerve, and Spinal Schwannomas

BACKGROUND

Management of sporadic schwannomas is often dictated by a patient's clinical presentation and the tumor's behavior. For patients who are managed nonsurgically, there are little data available about the expected natural history.

OBJECTIVE

To evaluate the natural history and growth patterns of extracranial schwannomas including tumors of the distal peripheral nerves, spine, and brachial plexus.

METHODS

A retrospective review was performed to identify patients with nonsyndromic extracranial schwannomas at a single tertiary care institution diagnosed between 2002 and 2019. Patient data and tumor characteristics including volume were recorded.

RESULTS

Two hundred twenty-seven patients were identified (mean age 51 years, 42% male, average of 27.8-month follow-up). Tumor location was distal peripheral nerve in 82, brachial plexus in 36, and paraspinal in 109. At the time of diagnosis, peripheral lesions were significantly larger than spinal (59 m 3 vs 13 cm 3 ) and brachial plexus lesions (15 cm 3 ). Distinct growth patterns were seen with both distal peripheral nerve and spinal lesions; 34/82 peripheral nerve lesions had fast growth (β = 0.176%/day), and 48 had slow growth (β = 0.021%/day; P < .01). Spinal schwannomas similarly had 30 fast-growing (β = 0.229%/day), 16 moderate-growing (β = 0.071%/day), and 63 slow-growing (β = 0.022%/day; P = .03) subtypes. The brachial plexus had relatively homogeneous growth patterns (β = 0.065%/day). Females had 2.9 times greater odds of having the fast-growing subtype.

CONCLUSION

Distinct growth patterns were seen in extracranial sporadic schwannomas based on tumor location and patient demographics. Fast (>80% volume change per year) vs slow (5%-10% per year) tumor growth can often be ascertained within 2 follow-up images. Awareness of these patterns might have implications for patient counseling and therapeutic decision-making.

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 case of pelvic schwannoma mimicking intra-ligamenter uterine fibroid: A case report

INTRODUCTION AND IMPORTANCE

Schwannomas are benign tumors originating from Schwann cells of nerve fibers. Pelvic schwannomas are extremely rare. Here, we present a case of a 48-year-old woman with a pelvic schwannoma imitating degenerating cystic leiomyoma.

CASE PRESENTATION

A 48-year-old woman presented with brown-yellowish bloody vaginal discharge, fever, abdominal enlargement, and pain. Abdominal ultrasound showed a homogeneous solid mass with a clear border separated from the uterus and left ovary. Computed tomography (CT) scan revealed a multilocular cystic mass with thick septa and solid enhancing component. Histopathological examination showed a mesenchymal tumor composed of cells with fine chromatin. The nuclei were oval or round, and some cells exhibited spindle and cigar-shaped nuclei. Tumor cells had an abundant amount of eosinophilic cytoplasm. Immunohistochemical examination demonstrated positive expression for S100 as specific staining for schwannomas. Mitosis was not found, and hyalinized blood vessels were observed.

CLINICAL DISCUSSION

Compression by the tumor into the surrounding organs, such as the bladder and intestines, could cause difficulty with defecation and urination in patients. The absence of specific signs and symptoms can lead to a misdiagnosis of pelvic schwannoma. Surgery is the treatment of choice. It is difficult to establish a definitive diagnosis before surgery. Laparotomy approach was taken and a histopathological examination was completed to confirm the diagnosis.

CONCLUSION

Unspecified pelvic pain with abdominal mass may suggest a rare tumor such as schwannoma. Transvaginal ultrasonography is incapable of reliably distinguishing between schwannoma and other tumors.

A Rare Case of an Adrenal Mass Proved to Be a Benign Cellular Schwannoma

Adrenal schwannomas are extremely uncommon tumors. We report the case of a 39-year-old male with a right adrenal mass. Laboratory tests were normal and radiological exams revealed the adrenal tumor. Open surgical adrenalectomy was performed. The postoperative course was uneventful. Microscopy and immunohistochemistry revealed a cellular schwannoma. Adrenal schwannomas are rare tumors, very difficult to diagnose in preoperative evaluation. Surgical excision of the tumor, histological and immunohistochemical examination of the specimen provide a definitive diagnosis. Prognosis is generally very good. Recurrence rates are related to positive surgical margins.

Robotic Nerve Sheath Tumor Resection With Intraoperative Neuromonitoring: Case Series and Systematic Review

BACKGROUND

Retroperitoneal nerve sheath tumors present a surgical challenge. Despite potential advantages, robotic surgery for these tumors has been limited. Identifying and sparing functional nerve fascicles during resection can be difficult, increasing the risk of neurological morbidity.

OBJECTIVE

To review the literature regarding robotic resection of retroperitoneal nerve sheath tumors and retrospectively analyze our experience with robotic resection of these tumors using a manual electromyographic probe to identify and preserve functional nerve fascicles.

METHODS

We retrospectively analyzed the clinical courses of 3 patients with retroperitoneal tumors treated at the National Institutes of Health by a multidisciplinary team using the da Vinci Xi system. Parent motor nerve fascicles were identified intraoperatively with a bipolar neurostimulation probe inserted through a manual port, permitting tumor resection with motor fascicle preservation.

RESULTS

Two patients with neurofibromatosis type 1 underwent surgery for retroperitoneal neurofibromas located within the iliopsoas muscle, and 1 patient underwent surgery for a pelvic sporadic schwannoma. All tumors were successfully resected, with no complications or postoperative neurological deficits. Preoperative symptoms were improved or resolved in all patients.

CONCLUSION

Resection of retroperitoneal nerve sheath tumors confers an excellent prognosis, although their deep location and proximity to vital structures present unique challenges. Robotic surgery with intraoperative neurostimulation mapping is safe and effective for marginal resection of histologically benign or atypical retroperitoneal nerve sheath tumors, providing excellent visibility, increased dexterity and precision, and reduced risk of neurological morbidity.

Surgical Management of Symptomatic Lumbar, Sacral, and Lumbosacral Plexus Tumors: a Peripheral Nerve Unit Experience

OBJECTIVE

Data concerning the surgical treatment of lumbosacral plexus tumors (LSPTs) is scarce. This study aims to present our experience with a series of 19 patients surgically treated for symptomatic LSPTs at our institution.

METHODS

This is a retrospective study of 19 patients surgically treated for symptomatic LSPTs from 2011 to 2019. Clinical data were retrieved from medical records and consisted of age, gender, clinical presentation, location of the lesion, surgical approach, final histopathologic diagnosis, follow-up time, outcomes, and complications.

RESULTS

Nineteen surgical procedures were conducted. Thirteen patients were female and six, male. The median age of patients was 45 years (range 20 to 63 years). No patients harbored genetic syndromes. Surgical treatment appears to be correlated to the reduction of pain in patients with peripheral nerve sheath tumors (PNSTs), as assessed by visual analog scale (VAS). Sixteen patients did not present with new-onset deficits during follow-up (84.2%), two of whom recovered from their preoperative deficit. Four patients presented with postoperative weakness. The histopathological diagnoses were 11 schwannomas, four neurofibromas, three metastases, and one lymphoma.

CONCLUSIONS

LSPTs are rare. When surgical treatment is indicated, it usually requires multidisciplinary management. Surgery appears to be effective concerning the reduction of pain in PNSTs and may also recover neurological deficits. Iatrogenic neurological deficits are an evident risk, such that intraoperative multimodal monitoring should always be performed if available. In lesions involving the sacral plexus, we found it to be indispensable.

Natural history of peripheral nerve schwannomas

BACKGROUND

Little information about the natural history of peripheral nerve schwannomas exists in the literature. The aim of this study was to determine the natural history of those tumors both in sporadic and schwannomatosis cases to determine their growth rates and patterns.

METHODS

In 44 patients from 3 surgical centers, hospital charts, follow-up records, and imaging studies were reviewed. Of these patients, 7 had sporadic schwannomatosis. Histological diagnosis was obtained in 37 patients (84%). Tumor growth rates were determined by calculating the absolute and relative growth rates.

RESULTS

On the 47 tumors analyzed, the median tumor size at diagnosis was 1.8 cm³, and the majority of tumors were located in the lower limb (62%). The absolute growth rate ranged from - 1.13 to 23.17 cm³/year (mean, 1.69 cm³/year). Relative annual growth rates ranged from - 9 to 166%/year (mean, 33.9%/year). There was no clear correlation between initial tumor size, age at diagnosis, and tumor growth rate. Six patients (13%) harbored "fast-growing" tumors (absolute growth rate > 2 cm³/year and relative growth rate > 35%/year) while 19% of tumors demonstrate no growth or negative growth. In schwannomatosis patients, each tumor displayed a distinct growth pattern.

CONCLUSION

This study confirms the slow-growing nature of most, but not all, peripheral nerve schwannomas. Additional studies are mandatory to explore the environmental factors influencing growth in sporadic cases and the precise growth patterns in schwannomatosis cases to detect the rare cases of malignant transformation and pave the way to the evaluation of future clinical trials.