Spontaneous hemothorax from a giant posterobasal thoracic ancient schwannoma: a case report of intercostal nerve tumor rupture

Introduction

Background

Schwannomas are encapsulated, slow-growing, and typically benign tumors originating from Schwann cells. They can arise from peripheral, cranial, or autonomic nerves (1). Histologically, they consist of Schwann cells, axons, macrophages, T cells, and fibroblasts, embedded in a vascularized extracellular matrix (2). A central mechanism in their pathogenesis involves inactivation of merlin, a tumor suppressor protein encoded by the NF2 gene on chromosome 22 (3,4). Malignant transformation is rare and typically results in epithelioid or primitive neuroectodermal morphology (5).

Rationale and knowledge gap

Intrathoracic schwannomas account for a minority of mediastinal tumors and are often asymptomatic or slowly progressive (6,7). According to published criteria, schwannomas with a maximum diameter greater than 8 cm are defined as “giant” tumors (8). In rare cases, they can present with acute complications such as hemorrhage or even arrhythmias due to cardiac compression (9,10).

Ancient schwannomas are a histological variant characterized by degenerative changes such as cystic degeneration, hemorrhage, calcification, and nuclear atypia, but without malignant behavior (11). Large posterior mediastinal masses with an acute onset may mimic other thoracic conditions, including diaphragmatic hernias, pulmonary lesions, or vascular emergencies (12), which complicates early diagnosis and emphasizes the need for prompt imaging and multidisciplinary evaluation.

Objective

We report a unique case of a giant thoracic ancient schwannoma presenting with spontaneous capsular rupture and hemothorax in a young, otherwise healthy adult. This case adds to the limited literature on giant schwannomas causing acute thoracic complications and underscores the importance of timely imaging, multidisciplinary evaluation, and prompt surgical management in posterior mediastinal masses. We present this article in accordance with the CARE reporting checklist (available at https://ccts.amegroups.com/article/view/10.21037/ccts-25-34/rc).

Case presentation

A 23-year-old Caucasian male with no relevant medical history presented in March 2025 to the emergency department with an acute onset of left-sided chest pain and dyspnea following physical exertion at work. There was no history of trauma or prior respiratory symptoms. Initial laboratory testing revealed a hemoglobin level of 11.8 g/dL and a red blood cell count of 4.2×10⁶/µL. Chest X-ray revealed a 10.8 cm left basal opacity (Figure 1), initially interpreted as a possible Bochdalek hernia.

Figure 1 Chest X-ray showing a 10.8 cm left basal opacity, initially suspected to represent a Bochdalek hernia. Black star showing pleural effusion.

Contrast-enhanced computed tomography (CT) demonstrated a large (10 cm × 9 cm × 6 cm), necrotic mass adjacent to the left diaphragm, displacing the lung parenchyma and associated with circumferential atelectasis and a moderate pleural effusion (Figure 2A). Further evaluation showed continuity between the lesion and the left T11 intercostal nerve, with extension into the corresponding vertebral foramen. Magnetic resonance imaging (MRI) confirmed the absence of spinal cord involvement (Figure 2B). Based on imaging characteristics, including the well-defined margins, cystic and necrotic components, and continuity with the intervertebral foramen, a neurogenic tumor such as a schwannoma was considered the most likely diagnosis. Other possibilities, such as neurofibroma, ganglioneuroma, and solitary fibrous tumor, were considered less probable due to the absence of diffuse infiltration or vascular encasement. Because of the acute hemorrhagic presentation and the risk of rebleeding, CT-guided biopsy was contraindicated. Given the necrotic features of the mass, a percutaneous biopsy was also considered likely to be non-diagnostic and was therefore not performed.

Figure 2 Preoperative imaging of the posterior mediastinal mass. (A) Contrast-enhanced CT scan showing a large, necrotic mass adjacent to the left diaphragm, displacing the lung parenchyma and associated with circumferential atelectasis and pleural effusion. Black star showing pleural effusion. (B) MRI confirms the absence of spinal cord infiltration and shows continuity with the left T11 intercostal nerve through the vertebral foramen. CT, computed tomography; MRI, magnetic resonance imaging.

Surgical exploration was initiated via video-assisted thoracoscopic surgery (VATS) through the sixth intercostal space. Approximately 800 mL of hemothorax was evacuated, and the bleeding source was identified as spontaneous rupture of the tumor capsule. No invasive maneuvers or procedures had been performed prior to surgery, confirming that the hemorrhage was truly spontaneous. Due to the tumor’s large size, its close adherence to the diaphragm and posterior mediastinum, and the impossibility of removing the specimen without rib spreading, the procedure was converted from VATS to a posterolateral thoracotomy just above the mass to allow safe and complete resection. Continuing thoracoscopically would have increased intraoperative risk without providing further advantage. The tumor was meticulously dissected from the adjacent lung, aorta, and posterior parietal pleura. The T11 intercostal nerve was ligated and transected proximally near the vertebral foramen. The tumor was resected en bloc with its capsule and the involved segment of the T11 intercostal nerve. A separate biopsy taken proximally near the vertebral foramen confirmed free margins and total removal of the lesion. Hemostasis was achieved using TachoSil^® and fibrin sealant. Estimated intraoperative blood loss was approximately 300 mL, in addition to the 800 mL of hemothorax evacuated at the beginning of the procedure. A neurosurgeon was on standby throughout the procedure, but posterior spinal access was ultimately not required, as the tumor was safely resected via a thoracic approach.

The postoperative course was uneventful, and the patient was discharged on postoperative day four.

Histopathological examination confirmed an ancient schwannoma measuring 10 cm × 9 cm × 6 cm (Figure 3). Microscopic examination revealed a spindle-cell neoplasm with alternating Antoni A and B areas. Verocay bodies were observed within the Antoni A regions. The tumor displayed degenerative changes consistent with the ancient variant, including cystic areas, focal hemorrhage, and nuclear atypia without evidence of malignancy. Immunohistochemical staining showed strong and diffuse positivity for S-100 protein. The Ki-67 proliferation index was approximately 10%, supporting the diagnosis of ancient schwannoma. No malignant features were observed. The patient has been followed for 6 months postoperatively, with no evidence of tumor recurrence on clinical examination and contrast-enhanced chest CT scan. Follow-up is scheduled every 6 months for the first 2 years with chest CT imaging, followed by annual imaging for an additional 3 years, after which further surveillance will be tailored according to the patient’s clinical and radiological condition.

Figure 3 Resected anatomical specimen measuring 10 cm × 9 cm × 6 cm. The tumor appears encapsulated, with evident rupture of the capsule, consistent with the intraoperative finding of hemothorax.

All procedures performed in this study were in accordance with the Declaration of Helsinki and its subsequent amendments. According to institutional policy at P. Pederzoli Hospital, case reports do not require formal approval by the ethics committee. 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.

Discussion

Key findings

This case describes a 23-year-old healthy male who presented with spontaneous hemothorax caused by rupture of a giant (10 cm × 9 cm × 6 cm) ancient schwannoma of the left T11 intercostal nerve. The tumor was successfully resected via a combined thoracoscopic and thoracotomic approach, and the patient recovered uneventfully, with no recurrence at 6-month follow-up. This report highlights the rarity of acute complications in schwannomas and the importance of prompt recognition and surgical management.

Strengths and limitations

A key strength of this report lies in the comprehensive preoperative workup, which included detailed imaging and multidisciplinary evaluation, allowing accurate surgical planning and safe resection of a giant ancient schwannoma complicated by hemothorax. Another important point is the emphasis on the need for prompt surgical intervention when clinical suspicion is high and acute complications arise, even in the absence of a preoperative histological diagnosis. The main limitation is the single-case nature of the report, which restricts generalizability, and the relatively short follow-up period (6 months), which may not fully capture the long-term risk of recurrence.

Comparison with similar research

Although giant thoracic schwannomas are rare (8), a few cases have been reported in the literature, with some presenting with hemothorax (10). In most reports, the bleeding originated from capsular rupture, with no active hemorrhagic source identified intraoperatively, consistent with our findings (13). Previous cases involved middle-aged patients, often with smaller tumors, whereas our case is unique for its occurrence in a young adult and for the ancient histological subtype (8). The outcome in our patient was favorable, similar to other surgically treated cases, underscoring the effectiveness of complete resection.

Explanations of findings

The acute hemothorax in this case is likely explained by spontaneous rupture of the tumor capsule, facilitated by degenerative changes typical of ancient schwannomas, including hemorrhage and cystic degeneration. Physical exertion may have contributed to increased intrathoracic pressure, precipitating rupture. The absence of an active bleeding source is in line with other reports, suggesting that capsule fragility rather than vessel erosion is the predominant mechanism (10,13-20) (Table 1). Preoperative imaging features, such as a well-defined, encapsulated mass with cystic degeneration and extension into the neural foramen, are typical of schwannomas and help distinguish them from other posterior mediastinal lesions (6,7,15). Neurofibromas often show diffuse nerve involvement, while ganglioneuromas tend to present with homogeneous attenuation and lack cystic degeneration (6,7). Solitary fibrous tumors usually arise from pleural surfaces and enhance homogeneously on CT (7). Definitive diagnosis of schwannoma relies on histopathological examination and immunohistochemistry, as serologic markers are unavailable and imaging features can be variable. In our case, the tumor showed typical features of an ancient schwannoma, including Antoni A and B areas, Verocay bodies, cystic degeneration, and hemorrhagic changes, with strong S100 protein expression. These findings confirmed the benign nature of the tumor and provided the basis for definitive management. Histopathological diagnosis of ancient schwannoma is based on the presence of distinctive degenerative features, including cystic degeneration, hemorrhage, calcification, and nuclear atypia, without significant mitotic activity or necrosis. These findings distinguish ancient schwannomas from cellular schwannomas, which are hypercellular with higher mitotic counts but lack degenerative changes, and from malignant peripheral nerve sheath tumors, which exhibit infiltrative growth, pleomorphism, and necrosis (11,12,14). Although the Ki-67 proliferation index reached 10%, this finding can be observed in ancient schwannomas due to degenerative nuclear atypia and reactive cellular proliferation, rather than malignant transformation. Recent evidence suggests that elevated Ki-67 in these lesions may be more closely associated with recurrence risk than with malignancy itself (21).

Implications and actions needed

This case emphasizes the need to consider posterior mediastinal schwannomas in the differential diagnosis of spontaneous hemothorax, particularly in young patients. MRI is particularly useful for evaluating intraspinal involvement and the relationship of the mass to neural and vertebral foramina, while CT provides superior assessment of calcifications and bony structures (22). Together, these imaging modalities and expert radiologic evaluation offer a comprehensive evaluation to guide surgical planning.

Conclusions

Spontaneous hemothorax from thoracic schwannomas is rare but should be considered in young patients with posterior mediastinal masses. This single case highlights the diagnostic challenges and supports the role of MRI and expert radiologic evaluation in guiding surgical planning. When resectable and clinical suspicion is high, prompt surgical excision is essential to ensure definitive treatment and avoid life-threatening complications.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://ccts.amegroups.com/article/view/10.21037/ccts-25-34/rc

Peer Review File: Available at https://ccts.amegroups.com/article/view/10.21037/ccts-25-34/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://ccts.amegroups.com/article/view/10.21037/ccts-25-34/coif). The 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 Declaration of Helsinki and its subsequent amendments. According to institutional policy at P. Pederzoli Hospital, case reports do not require formal approval by the ethics committee. 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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