Intraosseous schwannoma of the mobile spine: a report of twenty cases

Kyphoplasty of a C2 Body Intraosseous Schwannoma: A Case Report

We report a case of a 75-year-old male with an incidental and indeterminate lytic lesion of the C2 vertebral body. After rapid enlargement over 16 months, persistent neck pain, and concern for underlying occult malignancy, the patient underwent lesion biopsy and simultaneous balloon kyphoplasty. Histopathological analysis revealed the surprising diagnosis of intraosseous schwannoma. Spinal Intraosseous Schwannomas (SIS) are rare benign tumors, often mimicking more sinister processes on diagnostic imaging. Fortunately, their histologic appearance is identical to schwannomas found more commonly in the soft tissues, providing diagnostic certainty to otherwise ambiguous radiologic findings. Though rare, intraosseous schwannomas remain an important benign diagnostic consideration for incidental solitary lytic bone lesions. To our knowledge, this is the second published case of kyphoplasty involving an SIS.

Distinguishing Characteristics of Benign Versus Malignant Intraosseous Schwannomas: A Comparative Study

OBJECTIVES

Benign and malignant intraosseous schwannomas are rare, and primarily documented in case reports. This study aims to elucidate the differences in clinical features and imaging manifestations between these tumors. This will help clinicians identify malignant lesions at an early stage, reliable guide treatment decisions, and accurately predict outcomes.

METHODS

Eighteen patients who underwent surgery and got pathological examinations in our hospital from 2012 to 2023 were retrospectively reviewed. Among them, 14 cases were found benign with 4 malignant. In the benign group, patients underwent curettage followed by bone grafting, whereas the malignant group was treated with extensive resection or amputation. Patients' demographics and radiographic features, including gender, age at diagnosis, symptom duration, tumor location, tumor margin, and the ratio of sclerotic margins were documented and compared between these tumors. All imaging was reviewed by two fellowship-trained musculoskeletal radiologists, who also quantified the sclerotic margin ratio. The intraclass correlation coefficient was used to determine inter-observer agreement. The Mann-Whitney U test was applied for continuous clinical variables, and the chi-square test or Fisher's exact test for categorical variables.

RESULTS

In our series, the mean age of these patients was 43.1 ± 14.0 years, six patients were male and 12 were female. Pain was the predominant preoperative symptom. The average duration from symptom onset to initial physician visit was 28.5 ± 25.3 months for benign schwannomas and 8.3 ± 4.3 months for malignant schwannomas (p = 0.012). On plain radiographs, 13 (13/14) of benign schwannomas exhibited well-defined margins of bone destruction, compared to 1 (1/4) of malignant schwannomas (p = 0.019). Furthermore, benign schwannomas had a significantly higher sclerotic margin ratio (75.5%) than malignant ones (16.7%) (p = 0.001). No statistically significant difference was found between the two groups in terms of cortical bone destruction (p = 1.0). On MRI, both tumors demonstrated intermediate to slightly hypointense signal intensity on T1-weighted images and heterogeneous high signal intensities on T2-weighted images.

CONCLUSIONS

Despite their rarity, benign and malignant intraosseous schwannomas should be considered in the differential diagnosis for patients presenting with painful and radiographically lytic bone lesions, especially in the mandible, sacrum, and vertebrae. The ratio of sclerotic margins, which we proposed for the first time, in combination with symptom duration and the clarity of tumor margins, provide valuable diagnostic clues for distinguishing the malignancy of the tumors.

Safety and clinical contribution of computed tomography-guided biopsy for cervical spine lesion

INTRODUCTION

The purpose is to clarify the safety and clinical contribution of computed tomography (CT)-guided percutaneous needle-biopsy for patients with cervical spine lesion.

MATERIAL AND METHODS

Between June 2015 and August 2022, CT-guided percutaneous needle biopsies were performed for 15 cervical spine lesions of 15 patients (8 male, 7 female; 2-81 years old). The technical success, clinical contribution, and safety were evaluated. Technical success was defined as the completion of the biopsy procedure. Clinical contribution was defined as any contribution to the therapeutic strategy. Safety was assessed by the Common Terminology Criteria for Adverse Events, version 5.0.

RESULTS

The technical success rate was 100%. In all 15 patients, nontarget organs (e.g., major vessels, spinal cord) could be avoided. The post-biopsy histological diagnoses were myeloma (n = 2), metastatic adenocarcinoma (n = 2), chordoma (n = 2), Langerhans cell histiocytosis (n = 3), and one case each of malignant lymphoma, schwannoma, pyogenic spondylitis, non-pyogenic spondylitis, degenerative change, and non-pathological fracture. All of these diagnoses contributed to the therapeutic strategy decisions. One case of grade 2 pain was observed, but no complications with grade 3 or more were observed during or after the biopsies.

CONCLUSION

CT-guided percutaneous needle biopsies for cervical spine lesions were safe and clinically beneficial.

Long-term postoperative outcomes of spinal cellular schwannoma: study of 93 consecutive cases

BACKGROUND CONTEXT

Cellular schwannoma (CS) is a rare tumor that accounts for 2.8%-5.2% of all benign schwannomas. There is a dearth of up-to-date information on spinal CS in the literature.

PURPOSE

The aims of this study were to identify the proportion of CS cases amongst spinal benign schwannoma, describe the clinical features of spinal CS, and identify prognostic factors for local recurrence by analyzing data from 93 consecutive CS cases.

STUDY DESIGN

Retrospective review.

PATIENT SAMPLE

We analyzed 93 PSGCT screened from 1,706 patients with spine CS who were treated at our institute between 2008 and 2021.

OUTCOME MEASURES

Demographic, radiographic, operative and postoperative data were recorded and analyzed.

METHODS

We compared the clinical features of spinal CS from the cervical, thoracic, lumbar and sacral segments. Prognostic factors for local recurrence-free survival (RFS) were identified by the Kaplan-Meier method. Factors with p≤.05 in univariate analysis were subjected to multivariate analysis by Cox regression analysis.

RESULTS

The proportion of spinal CS in all benign schwannomas was 6.7%. The mean and median follow-up times for the 93 patients in this study were 92.2 and 91.0 months respectively (range 36-182 months). Local recurrence was detected in 11 cases, giving an overall recurrence rate of 11.7%, with one patient death. Statistical analysis revealed that tumor size ≥5 cm, intralesional resection, and Ki-67 ≥5% were independent negative prognostic factors for RFS in spinal CS.

CONCLUSIONS

Whenever possible, en bloc resection is recommended for spinal CS. Long-term follow-up should be carried out for patients with tumor size ≥5 cm and postoperative pathological Ki-67 ≥5%.

Surgical Management of Intraosseous Neurofibroma in Cervical Spine: A Case Report

CASE

A 30-year-old man had cervical radiculomyelopathy and neck pain caused by a massive intraosseous neurofibroma (IONF) originating from the C6 vertebrae. We performed posterior tumor resection with spinal instrumentation and fusion from C3 to T2 and a follow-up resection procedure of the remaining C6 anterior tumor, sacrificing the affected vertebral artery (VA), which accordingly required bypass surgery at 2 months recovery. Reconstruction using a titanium mesh cage was successfully performed. There were no local recurrences at 2 years postoperatively.

CONCLUSIONS

Total tumor resection split into 2 stages with sacrifice of the affected VA is a feasible option for treatment of IONF.

Giant Invasive Intradural Extramedullary Lumbar Schwannoma: A Case Report and Literature Review

Schwannomas are benign nerve sheath tumors that arise from Schwann cells, which are responsible for producing the myelin sheath that surrounds nerves. They are typically slow-growing and can occur in various locations in the body, including the lumbar region of the spine. We present a case of giant invasive intradural extramedullary schwannoma managed with posterior lumbar interbody fusion (PLIF) and laminectomy with excellent results. A 58-year-old man presented with lower back pain radiating to the right leg for six months. He had no history of trauma or systemic disease. Lumbosacral magnetic resonance imaging (MRI) showed a well-defined mass at the L3-L4 level compressing the right nerve root. The patient was managed with L3-L4-L5 transpedicular fixation and right-side laminectomy L3-L4 for resection of the tumor. Histopathological examination confirmed the diagnosis of schwannoma. The patient had a favorable postoperative recovery and experienced a resolution of symptoms. Lumbar schwannomas are rare they can cause significant symptoms and require appropriate diagnosis and management. Microsurgery is the preferred treatment, and endoscopic microsurgery is the most promising technique.

Posterior paramedian approach combined with a novel inverted V-shaped surgical access for intraspinal schwannomas: a retrospective case series study

OBJECTIVE

To explore the efficacy and safety of the posterior paramedian approach combined with a novel inverted V-shaped surgical access for the treatment of intraspinal schwannomas.

METHODS

This study retrospectively reviewed consecutive patients who underwent surgical resection of the intraspinal schwannomas via the inverted V-shaped approach at our center between January 2016 and May 2021. Changes between the preoperative and postoperative visual analog scale (VAS) scores and neurological function Japan Orthopaedic Association (JOA) scores were assessed. Secondary outcomes such as success rate of tumor resection, operation time, blood loss, spinal stability, and disruption degree of intervertebral joints. Postoperative complications were also investigated.

RESULTS

Of these 36 consecutive patients, there were 6 cases in the cervical spine, 2 cases at the cervical-thoracic junction, 11 cases in the thoracic spine, 4 cases at the thoracic-lumbar junction and 13 cases in the lumbar spine. The average operation time was 99 min, and the average blood loss was 95.4 mL. The tumor removal rate was 100%. Postoperative CT re-examination showed that the spinous processes were intact in all cases, the facet joint surfaces were intact in 32 cases. At the time of last follow-up, the median JOA score was 25 (9-27), which was significantly improved compared to the preoperative median JOA score of 15 (10-22) (P < 0.01). The overall excellent and good rate were 88.9 %. The median VAS score at post-surgery was 0 (0-2), which was significantly improved compared to the preoperative median VAS score of 4 (2-8) (P < 0.01). As for complications, there were no cases of cerebrospinal fluid leakage or spinal instability. Three patients who had a postoperative fever finally recovered after lumbar cistern drainage.

CONCLUSION

The inverted V-shaped surgical access via the posterior paramedian approach is an effective and safe method for the treatment of intraspinal schwannomas.

Imaging Features of Intraosseous Schwannoma: A Case Series and Review of the Literature

To characterize the imaging features of patients with pathologically confirmed intraosseous schwannoma (IOS), institutional pathology and imaging databases were searched for IOS cases over a period of 17 years. A musculoskeletal radiologist evaluated all imaging studies. Additionally, a literature search was performed to identify IOS cases that had imaging findings of at least two modalities. Six patients (one female, five males, mean age of 50 ± 14 years) with IOS were identified, with all lesions localized to the lumbosacral region. Radiographic imaging was available in four patients, while all patients underwent CT and MR imaging. Radiographs depicted lytic lesions, and CT depicted heterogeneous expansile lesions with centrally hypodense areas and peripheral sclerosis. All cases involved extra-osseous extension, producing a mass effect on adjacent soft tissues and nerve roots. On MRI, the neoplasms displayed iso- to- slightly- low signal intensity on T1-weighted images and hyperintense signal intensity on T2-weighted images with heterogeneous enhancement. The literature review resulted in 102 IOS cases, which to the best of our knowledge, is the largest review on IOS, and the imaging findings of the previously published cases were the same as our cases. IOSs are rare benign neoplasms that should be considered in the differential diagnosis of well-defined expansile lytic lesions with sclerotic borders. This is particularly important in middle-aged adults with mandibular, sacral, or vertebral body mass.

Differentiation of benign and malignant spinal schwannoma using guided attention inference networks on multi-source MRI: comparison with radiomics method and radiologist-based clinical assessment

BACKGROUND

Differentiating diagnosis between the benign schwannoma and the malignant counterparts merely by neuroimaging is not always clear and remains still confounding in many cases because of atypical imaging presentation encountered in clinic and the lack of specific diagnostic markers.

PURPOSE

To construct and validate a novel deep learning model based on multi-source magnetic resonance imaging (MRI) in automatically differentiating malignant spinal schwannoma from benign.

MATERIAL AND METHODS

We retrospectively reviewed MRI imaging data from 119 patients with the initial diagnosis of benign or malignant spinal schwannoma confirmed by postoperative pathology. A novel convolutional neural network (CNN)-based deep learning model named GAIN-CP (Guided Attention Inference Network with Clinical Priors) was constructed. An ablation study for the fivefold cross-validation and cross-source experiments were conducted to validate the novel model. The diagnosis performance among our GAIN-CP model, the conventional radiomics model, and the radiologist-based clinical assessment were compared using the area under the receiver operating characteristic curve (AUC) and balanced accuracy (BAC).

RESULTS

The AUC score of the proposed GAIN method is 0.83, which outperforms the radiomics method (0.65) and the evaluations from the radiologists (0.67). By incorporating both the image data and the clinical prior features, our GAIN-CP achieves an AUC score of 0.95. The GAIN-CP also achieves the best performance on fivefold cross-validation and cross-source experiments.

CONCLUSION

The novel GAIN-CP method can successfully classify malignant spinal schwannoma from benign cases using the provided multi-source MR images exhibiting good prospect in clinical diagnosis.

Intraosseous schwannoma in the clivus mimicking chordoma treated with endoscopic endonasal surgery: A case report

Background:

Intraosseous schwannomas are extremely rare and they have not yet been reported to occur in the clivus. We report a schwannoma in the clivus mimicking chordoma and review intraosseous schwannomas of the skull.

Case Description:

A 62-year-old man presented with gradually worsening hoarseness with dysphagia and atrophy of the left tongue, trapezius muscle, and sternocleidomastoid muscle. Magnetic resonance imaging showed that the tumor was mainly located in the clivus, and a computed tomography (CT) scan revealed an osteolytic lesion with expansion of the clivus and preservation of the bony cortex. Endoscopic endonasal surgery was performed to diagnose and treat symptoms. The tumor was subtotally removed without any complications. The histopathological findings revealed typical schwannoma, which showed Antoni A and Antoni B patterns positive for S100 protein. Based on the preoperative imaging, intraoperative and histopathological findings, the tumor was considered to be an intraosseous schwannoma in the clivus, and no recurrence was observed after 1 year of postoperative follow-up.

Conclusion:

Even though the intraosseous schwannoma in the clivus is uncommon, it should be considered as a differential diagnosis if an expansive lesion without destruction of the cortical bone is shown on CT as well as iso-hyperintensity on T2-weighted magnetic resonance imaging.

Benign and malignant diagnosis of spinal tumors based on deep learning and weighted fusion framework on MRI

BACKGROUND

The application of deep learning has allowed significant progress in medical imaging. However, few studies have focused on the diagnosis of benign and malignant spinal tumors using medical imaging and age information at the patient level. This study proposes a multi-model weighted fusion framework (WFF) for benign and malignant diagnosis of spinal tumors based on magnetic resonance imaging (MRI) images and age information.

METHODS

The proposed WFF included a tumor detection model, sequence classification model, and age information statistic module based on sagittal MRI sequences obtained from 585 patients with spinal tumors (270 benign, 315 malignant) between January 2006 and December 2019 from the cooperative hospital. The experimental results of the WFF were compared with those of one radiologist (D1) and two spine surgeons (D2 and D3).

RESULTS

In the case of reference age information, the accuracy (ACC) (0.821) of WFF was higher than three doctors' ACC (D1: 0.686; D2: 0.736; D3: 0.636). Without age information, the ACC (0.800) of the WFF was also higher than that of the three doctors (D1: 0.750; D2: 0.664; D3:0.614).

CONCLUSIONS

The proposed WFF is effective in the diagnosis of benign and malignant spinal tumors with complex histological types on MRI.

Clinical Effect of Laminectomy with Lateral Mass Screw Fixation in Treating Cervical Schwannoma: A Retrospective Study

Background

The objective of this study was to evaluate the clinical effectiveness and safety of laminectomy combined with lateral mass screw fixation in treating cervical intradural extramedullary schwannoma.

Methods

We retrospectively collected and analyzed medical records of 38 patients who underwent resection of cervical intraspinal schwannoma between January 2012 and April 2019. Based on different surgical procedures, two groups were divided among all participants: laminectomy-only (n = 21) and laminectomy with instrumented fixation (n = 17); the minimum follow-up time was 1 year. The visual analogue scale (VAS) score and neck disability index (NDI) were utilized for pain assessment; the Japanese Orthopedic Association (JOA) score was carried out for the assessment of neurological impairment. Radiographic changes of Cobb angle were compared before and after the surgery.

Results

Consequently, demographics were well matched in both groups, without any statistical difference (P > 0.05). Compared with preoperation, both surgical procedures significantly improved VAS, NDI, and JOA scores (P < 0.001), but no differences between them (P > 0.05). In terms of postoperative spinal instability/deformity, laminectomy-only caused more events than instrumented fixation, which is statistically significant (P < 0.001).

Conclusions

In summary, laminectomy with lateral mass screw fixation is an effective and safe approach to treat cervical intraspinal schwannoma, which is likely to be a better choice than the laminectomy-only approach.

Primary Paraganglioma of the Spine: A Systematic Review of Clinical Features and Surgical Management in Cauda Equina vs Non-Cauda Equina Lesions

BACKGROUND

Primary spine paragangliomas are rare tumors. Surgical resection plays a role, but aggressive lesions are challenging. We reviewed the literature on primary spine paragangliomas.

METHODS

PubMed, Scopus, Web of Science, and Cochrane were searched upon the PRISMA guidelines to include studies on primary spine paragangliomas. Clinical-radiological features, treatments, and outcomes were analyzed and compared between cauda-equina vs non-cauda-equina tumors.

RESULTS

We included 143 studies comprising 334 patients. Median age was 46 years (range, 6-85). The most frequent symptoms were lower-back (64.1%) and radicular (53.9%) pain, and sympathetic in 18 patients (5.4%). Cauda-equina paragangliomas (84.1%) had frequently lumbar (49.1%) or lumbosacral (29%) locations. Non-cauda-equina tumors were mostly in the thoracic (11.4%), thoracolumbar (5.1%), and cervical (3.6%) spine. Median tumor diameter was 2.5cm (range, 0.5-13.0). Surgical resection (98.5%) was preferred over biopsy (1.5%). Decompressive laminectomy (53%) and spine fusion (6.9%) were also performed. Adjuvant radiotherapy was delivered in 39 patients (11.7%) with aggressive tumors. Post-treatment symptomatic improvement was described in 86.2% cases. Median follow-up was 19.5 months (range, 0.1-468.0), and 23 patients (3.9%) had tumor recurrences. No significant differences were found between cauda-equina vs non-cauda-equina tumors.

CONCLUSION

Surgical resection is effective and safe in treating primary spine paragangliomas; however, adjuvant treatments may be needed for aggressive lesions.

Diagnostic yield, accuracy, and complication rate of CT-guided biopsy for spinal lesions: a systematic review and meta-analysis

BACKGROUND

CT-guided biopsy is a commonly used diagnostic procedure for spinal lesions. This meta-analysis aims to investigate its diagnostic performance and complications, as well as factors influencing outcomes.

METHODS

A systematic review of the literature was performed to identify studies reporting outcomes of CT-guided biopsies for spinal lesions. Diagnostic yield (ie, the rate of procedures resulting in a specific pathological diagnosis) and diagnostic accuracy (ie, the rate of procedures resulting in the correct diagnosis) were the primary outcomes of interest. Complications following biopsy procedures were also included.

RESULTS

Thirty-nine studies with 3917 patients undergoing 4181 procedures were included. Diagnostic yield per procedure was 91% (95% CI 88% to 94%) among 3598 procedures. The most common reason for non-diagnostic biopsies was inadequacy of sample. No difference in diagnostic yield between different locations and between lytic, sclerotic, and mixed lesions was found. Diagnostic yield did not differ between procedures using ≤13G and ≥14G needles. Diagnostic accuracy per procedure was 86% (95% CI 82% to 89%) among 3054 procedures. Diagnostic accuracy among 2426 procedures that yielded a diagnosis was 94% (95% CI 92% to 96%). Complication rate was 1% (95% CI 0.4% to 1.9%) among 3357 procedures. Transient pain and minor hematoma were the most common complications encountered.

CONCLUSION

In our meta-analysis of 39 studies reporting diagnostic performance and complications of CT-guided biopsy, we found a diagnostic yield of 91% and diagnostic accuracy of 86% with a complication rate of 1%. Diagnostic yield did not differ between different locations, between lytic, sclerotic and mixed lesions, and between wide- and thin-bore needles.

Intraosseous Melanotic Schwannoma in the Sacrum Mimicking Primary Bone Tumor

Primary tumors of sacrum are rarely seen, and the differential diagnosis is extensive, such as chordomas, giant cell tumors, and schwannomas. Sacral intraosseous schwannomas (IOSs) are very rare and encompass approximately 1%–5% of all spinal schwannomas. Melanotic schwannomas (MSs) are categorized as an unusual variant of benign schwannomas; however, they sometimes follow a malignant course. The authors present a case of MS with intraosseous extension into sacrum in a 48-year-old male arising from the left S2 nerve root. Magnetic resonance imaging (MRI) and computed tomography (CT) scan demonstrated a destructive mass in the sacrum. He was made a diagnosis with MS by 18F-fluoro-deoxy-glucose positron-emission-tomography (¹⁸F-FDG PET) and open biopsy. The tumor was blackish-colored and vascular-rich fragile tumor covered by fibrous capsule. The floor of the tumor was not encapsulated and invading into the sacral bone. Total removal of the tumor together with the left S2 nerve of origin via posterior approach was achieved. The patient made dramatic recovery of neurological symptoms and tumor recurrence is not seen for 6-month follow-up period. MS is a benign tumor with potential for aggressive behavior and capacity to metastasize. Therefore, total removal of the tumor and careful postoperative follow-up are recommended. Postoperative spinopelvic stability also needs to be taken into consideration. The authors discuss our successful management with a focus on diagnostic process, surgical planning, and histological consideration to provide the most up-to-date guidance on managing this challenging tumor.

Spinal intraosseous schwannoma without spinal canal and neuroforamina involvement: A case report

BACKGROUND

Spinal intraosseous schwannomas (SIS) are rare, and as yet have not been fully described in the literature. The first case of SIS was reported in 1971, and 24 cases of SIS have been reported so far. However, including the present case, there are only seven cases without spinal canal and neuroforamina involvement.

CASE SUMMARY

A 56-year-old man presented with a history of neck pain for 2 years. An obvious osteolytic destruction of the seventh cervical (C7) vertebra was observed on imaging examination. Magnetic resonance imaging of the cervical spine showed space-occupying lesions in the C7 vertebra, and destruction of the anterior cortex of the vertebra. The lesions had an exophytic component that extended from the C7 vertebra into the soft tissue on the front side. The foramen transversarium on both sides were intact. The patient underwent surgical biopsy and focal excision of the C7 lesion. The diagnosis of “schwannoma” was verified by postoperative pathological examinations. In a review of the literature, this is the seventh case of SIS without spinal canal and neuroforamina involvement, and the third reported case of type VIII SIS. We discussed our case with respect to reported classification characteristics of SIS.

CONCLUSION

SIS is a very rare tumor. We report a rare case that may be important for further classification of osteo-schwannoma. The establishment of a complete disease classification is of high importance for the treatment and prognosis of this disease. Thus, more basic studies and retrospective analysis of related cases are necessary.

Intraosseous Thoracic Schwannoma: Case Report and Review of the Literature

BACKGROUND

Intraosseous locations are extremely rare when it comes to schwannomas and account for 0.2% of primary bone tumors. The most common intraosseous locations include the mandible and sacrum, while cervical, thoracic, and lumbar spine lesions are even more uncommon.

CASE DESCRIPTION

We describe a 56-year-old female patient with incidental finding of an intraosseous lytic lesion within the vertebral body of T1. Complete surgical excision was performed with instrumented fusion. Histopathology results confirmed a World Health Organization grade I schwannoma.

CONCLUSIONS

Our case is the fourth case of purely intraosseous schwannoma described in the mobile spine in the literature, with good results both clinically and radiologically after complete surgical resection.