Operative approach of chest wall schwannoma: a case report

Introduction

Background

Schwannomas are benign tumors of nerve sheaths originating from Schwann cells of peripheral nerves (1). These tumors can develop in any peripheral nerve; however, they most frequently arise from nerves in the head and neck (2). Less commonly, schwannomas also occur in the chest wall (3). They typically manifest in individuals during their second to fifth decade of life (4). While schwannomas are often asymptomatic, they may manifest with symptoms of pain, numbness, or paresthesia due to nerve impingement. Surgical intervention is a curative option for carefully selected patients (4).

Rationale and knowledge gap

Schwannomas are the most commonly encountered peripheral nerve tumor in the mediastinum, typically occurring in the posterior mediastinum (5). Rarely, schwannomas can also develop in the chest wall arising from the intercostal nerves (6). Of chest wall schwannomas, only 5% are known to arise from the lateral chest wall rather than the posterior mediastinum (3). To date, only one case of axillary schwannoma originating from the long thoracic nerve has been reported (4). Other cases of schwannomas have been documented in the thoracic spine, originating from the thoracic nerve root (2,7,8). Diagnosis of schwannoma can be challenging due to its slow-growing and asymptomatic nature; symptoms usually arise due to a mass effect (4). Differential diagnoses to consider for an intramuscular chest wall lesion are sarcomas, glomus tumors, hemangiomas, and neurofibromas (6). Imaging does not allow for complete differentiation, and because there is the potential for malignant transformation, biopsy and surgical excision are recommended for definitive diagnosis and management (3,4,6). Surgical resection with complete nerve preservation can be challenging due to the nature of the tumor, however, it is possible in some cases to perform enucleation without nerve fascicle injury (4).

Objective

The purpose of this report is to present the operative management of a chest wall schwannoma originating from the long thoracic nerve. We present this article in accordance with the CARE reporting checklist (available at https://asj.amegroups.com/article/view/10.21037/asj-25-13/rc).

Case presentation

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

A 52-year-old male presented with an incidentally diagnosed right chest wall mass during evaluation for right shoulder pain. He had no history of cancer or other significant medical issues. The patient denied shortness of breath, fevers, chills, weight loss, numbness, tingling, or loss of motor function of his right upper extremity. On examination, there were no skin lesions or discoloration. Scapular protrusion was noted, but he had a normal range of motion of this upper extremity. He had tenderness to palpation of his right axillary lymph node.

Magnetic resonance imaging (MRI) of the right shoulder with contrast was completed to rule out shoulder pathology due to his right shoulder pain. The MRI incidentally revealed a 5 cm × 2.8 cm × 6.4 cm rim-enhancing mass, suspected to have central necrosis (Figure 1). The mass was elevating the serratus anterior muscle, located within or deep to the muscle belly, and anterior to the scapular musculature. Edema and enhancement extended more anteriorly than posteriorly, with significant neovascularity. There were also unrelated denervation changes in the right shoulder. The patient was referred to orthopedic oncology who recommended computed tomography (CT) of the chest to evaluate for mass invasion and to rule out lesions in the lungs, as well as CT-guided biopsy of the mass. The CT scan, completed one month after the MRI, revealed a 5.3 cm × 2.9 cm × 7.7 cm intramuscular mass and a 3.8 mm nonspecific nodule in the left lower lobe. CT-guided biopsy confirmed the intramuscular mass as a schwannoma. Although schwannomas rarely undergo malignant transformation and are slow growing, they can cause pain secondary to mass effect. It is reasonable to follow with conservative management if asymptomatic with a low suspicion for malignancy; however, in this case, the patient was symptomatic with pain and winged scapula, and he was therefore desirous for excision.

Figure 1 MRI of the right shoulder and chest wall with contrast revealed a 5 cm × 2.8 cm × 6.4 cm rim-enhancing mass (arrows). (A) Axial STIR image; (B) coronal T2 weighted image; (C) sagittal STIR image. MRI, magnetic resonance imaging; STIR, short tau inversion recovery (MRI imaging sequence).

Surgical management

The patient elected to proceed with surgery. An oblique incision was made along the 5th rib, overlying the palpable mass. A latissimus and serratus sparing incision and dissection were performed. The mass undermined the serratus anterior muscle but showed no gross invasion. It was resected with the capsule intact, and the branch of the long thoracic nerve leading to the mass was identified. Preservation of this branch of the long thoracic nerve was not possible due to the intimate involvement of the schwannoma with this branch; however, the remainder of the dissection was performed to preserve all of the long thoracic nerve, except the branch mentioned. This branch was suture ligated and divided. The specimen was sent to pathology for frozen section to confirm the diagnosis of schwannoma given the unusual location. Hemostasis was achieved via bipolar coagulation. A 7 French flat Blake drain was placed inferior to the serratus muscle layer. The serratus and latissimus muscles were then reapproximated and another 7 French flat Blake drain was placed in the subcutaneous tissue. Both Blake drains were placed to bulb suction.

Inspection of the gross excised specimen revealed a well-circumscribed lobule of soft tissue measuring 5.9 cm × 2.9 cm × 3 cm (Figure 2). The surface was tan-brown and heterogeneous, with a small ill-defined cystic cavity containing serosanguineous fluid. Necrosis was present in 20–30% of the area. Negative margins were confirmed. The pathology was consistent with schwannoma, benign fibroadipose tissue, and three benign lymph nodes.

Figure 2 Gross specimen.

The patient’s postoperative course was uneventful and without complications. His postoperative physical exam was notable for scapular winging, which was unchanged from his preoperative exam, however, the patient did not have any functional deficits and cleared physical therapy without difficulty. He was discharged in stable condition. He returned for a postoperative visit 10 days after surgery for drain removal. He had improved chest wall soreness and no muscle weakness. He had returned to his usual activities by this follow-up visit.

Discussion

Key findings

This report presents the second documented case of a chest wall schwannoma originating from the long thoracic nerve. The patient, a 52-year-old male, was incidentally diagnosed with the mass during evaluation for shoulder pain. He presented with winged scapula secondary to impinged long thoracic nerve branch and tumor location. Imaging studies (MRI and CT) revealed a mass measuring 5.9 cm × 2.9 cm × 3 cm, located deep to the serratus anterior muscle. Pathology of the excised mass confirmed a schwannoma with negative margins. This case is notable for its location, as schwannomas originating from the long thoracic nerve in the chest wall are extremely rare. The surgical resection led to a successful postoperative course.

Strengths and limitations

Chest wall schwannomas and chest wall sarcomas share similar clinical and radiographic characteristics, but have different prognostic and therapeutic implications. The precise diagnosis of schwannoma was key to allow for surgical resection and, possibly, nerve preservation. Due to the rarity of this presentation, performance of the upper extremity is not well defined. The long thoracic nerve innervates the serratus anterior muscle, which helps move the shoulder and stabilizes the scapula (9). Sacrifice of this nerve presents the possibility for long-term weakness, reduced range of motion, and winged scapula (9). In our case, the patient’s initial presentation showed long thoracic nerve involvement with a winged scapula, thus, the consequences of sacrificing the nerve intraoperatively are limited. There are no existing studies that highlight follow-up or recurrence rates after surgical removal.

Comparison to existing literature

Previous reports have documented schwannomas originating from the thoracic nerve root or presenting in the axilla, but this is the first to describe a schwannoma arising directly from the long thoracic nerve in the chest wall (4,7). The only other reported case of schwannoma arising from the long thoracic nerve presented similarly as a palpable mass without pain or paresthesia, but was found in the axilla covered by the pectoralis major muscle and was misdiagnosed as an accessory breast (4). In comparison, our case was presented in the lateral chest wall and was covered by the serratus anterior muscle. The management of this earlier case differed with the use of intraoperative electrical stimulation to identify the long thoracic nerve, as well as the ability to preserve the nerve fascicle (4). Microsurgical dissection and intracapsular enucleation are established techniques for preserving nerve fibers while dissecting along the tumor or within the tumor capsule (10,11). Continuous electromyography (EMG) monitoring of the serratus anterior muscle may have been considered if he had not presented with a winged scapula at the time of surgery.

Explanations of findings

The patient’s exam, the mass’s location deep to the serratus anterior muscle, and its relationship to the long thoracic nerve explain the tumor’s pathology and its origin. MRI sensitivity rates for schwannomas are approximately 85–91% (12,13). Therefore, our MRI and CT findings were sufficient modalities to confirm suspicion of chest wall malignancy, followed by confirmational CT-guided biopsy of the mass. Other considerations would be to add neurography sequences as an adjunct to the MRI that would provide detailed visualization of the peripheral nerves. Due to the typical benign, slow-growing nature of schwannomas with rare malignant transformation, it is reasonable to consider conservative management. In an asymptomatic patient, with classically benign radiographic features such as homogeneity and smooth to multilobulated contour, conservative management with observation is a suitable choice. In our case, however, we elected to proceed with surgical excision due to the patient’s preference, symptoms, and the necrotic component to his imaging. Intraoperative findings in our case of intimate tumor involvement with a branch of the long thoracic nerve did not allow for complete nerve-sparing, however, each case should be carefully evaluated intraoperatively for the use of nerve-sparing technique if possible.

Implications and actions needed

Given the rarity of schwannomas arising from the long thoracic nerve in the chest wall, it is important for clinicians to consider this diagnosis in the workup for chest wall masses. Early and accurate diagnosis through imaging, followed by biopsy, will guide surgical management. Long-term follow-up is recommended to monitor for functional impairments. Further research into the benefits of nerve preservation and tumor recurrence would guide surgical decision-making.

Conclusions

This case report highlights the operative approach for chest wall schwannomas originating from the long thoracic nerve. It is important to consider schwannoma in the differential diagnosis of a chest wall mass. Long thoracic nerve involvement should be considered in the setting of scapular winging. Despite the mass’s unusual location for a schwannoma, a combination of MRI, CT, and biopsy are important for diagnosis. Surgical resection is the mainstay for treatment. Nerve-sparing techniques such as microsurgical dissection with intracapsular enucleation with EMG monitoring may be utilized if nerve function is not impaired. Although postoperative recovery was uneventful, ligation of a secondary branch from the long thoracic nerve raises concerns regarding potential long-term functional outcomes. In our case, we only have short-term follow-up for this patient, however, long-term functional implications of long thoracic nerve resection include weakness, reduced range of motion, and winged scapula. This case underscores the importance of considering schwannomas in the differential diagnosis of chest wall masses and emphasizes the need for continued vigilance in monitoring long-term recovery.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://asj.amegroups.com/article/view/10.21037/asj-25-13/rc

Peer Review File: Available at https://asj.amegroups.com/article/view/10.21037/asj-25-13/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-25-13/coif). C.N.E. received speaker honorarium from Atricure and consultation payment from Johnson & Johnson MedTech, Atricure, and Cook Medical. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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