Unilateral biportal endoscopy for thoracic intradural meningioma: a two-case technical report and narrative discussion

Introduction

Spinal meningiomas (SM) are the most frequent primary neoplasms of the spinal canal, representing a substantial proportion of intradural extramedullary tumors. They account for approximately 20–40% of cases and nearly one-quarter to almost half of reported primary intraspinal tumors. Despite this predominance in the spine, SM represent only a small fraction of all meningiomas (approximately 1.2–12.7%) and about 3% of central nervous system meningiomas, while contributing to roughly 25% of all spinal cord tumors (1,2).

SM show a marked female predominance, with female-to-male ratios approaching 4:1, most frequently diagnosed in middle-aged and elderly patients. Several series report female representation exceeding 80%. Although uncommon in the general population, with an estimated annual incidence of 0.33 per 100,000 inhabitants, rare variants—including ossified SM—have been sporadically described (2-4).

Anatomically, SM arise predominantly in the intradural extramedullary compartment and may occur at any spinal level. Thoracic SM are the most common, representing 60–65% of cases, followed by cervical and lumbar segments. Posterior and posterolateral locations are typical, whereas ventral locations are less frequent. Histologically, psammomatous meningiomas are the most common subtype in the thoracic spine, with most classified as benign World Health Organization (WHO) grade I tumors (2,3).

Molecular studies suggest biological heterogeneity by spinal location. Thoracic SM are more frequently associated with NF2 mutations, show marked female predominance, and are usually dorsal or dorsolateral. In contrast, AKT1-mutant meningiomas are more common in the cervical spine and often ventrally located. These distinctions may influence surgical planning (5).

Clinically, SM typically present with slowly progressive neurological deficits due to chronic spinal cord compression. Symptoms include motor weakness, gait disturbance, sensory deficits, and paraparesis. Thoracic lesions often manifest as chronic dorsal pain, progressive myelopathy, or a defined sensory level. While most cases occur in older adults, SM may occasionally present in younger patients, particularly in association with genetic conditions such as neurofibromatosis type 2 (2-4).

Surgically, SM generally have a favorable prognosis. Gross total resection (GTR) remains the treatment of choice, offering high rates of neurological improvement and low recurrence. Historically, open microsurgical approaches were used (1). Open posterior approaches, including laminectomy or hemilaminectomy with microsurgical resection, achieve high rates of GTR and durable tumor control. In 1938, Cushing and Eisenhardt performed the first spinal meningioma resection, describing it as “one of the most satisfying of all surgical procedures” (1). Open microsurgery has remained the gold standard, providing excellent long-term outcomes when complete resection is achieved (3).

Despite efficacy, open surgery is associated with approach-related morbidity: extensive paraspinal muscle dissection, postoperative pain, prolonged hospital stay, and potential spinal instability—particularly relevant in elderly patients (6). These limitations have driven the development of minimally invasive spine surgery (MISS), which aims to preserve oncological outcomes while minimizing soft tissue disruption (7).

Over the past decade, MISS approaches, including tubular retractor systems and unilateral hemilaminectomy techniques, have shown comparable rates of tumor resection and neurological recovery to open surgery. They are associated with reduced blood loss, shorter operative times, faster recovery, and decreased hospital stay (7,8). Specific minimally invasive strategies, such as posterolateral transpedicular approaches, have been effective for ventrally located thoracic intradural extramedullary tumors, offering advantages over direct posterior approaches in selected cases (9).

Advances in spinal endoscopy have enabled endoscopic techniques for intradural pathology. Uniportal approaches have been described; however, their use is limited by restricted instrument maneuverability and a steep learning curve, especially in complex cases. Unilateral biportal endoscopy (UBE) has emerged as a promising alternative, providing independent visualization and working portals, improved ergonomics, enhanced illumination, and magnification comparable to conventional microsurgery (10-12). Shao et al. first reported UBE for a thoracic intradural extramedullary meningioma, achieving complete tumor removal with minimal morbidity (10). Huang et al. subsequently reported successful resection of a high-grade thoracic meningioma using UBE, supporting its feasibility even in complex cases (11). Peng et al. later highlighted the versatility of UBE for thoracic intradural extramedullary tumors, emphasizing reduced tissue trauma, preservation of posterior elements, and rapid recovery (12).

Systematic reviews comparing open versus minimally invasive approaches for intradural extramedullary tumors report emerging evidence favoring MISS, particularly regarding perioperative outcomes, while maintaining comparable functional and oncological results (7,8). Given the thoracic spine’s anatomical constraints and the typical dorsal or dorsolateral tumor location, MISS and endoscopic approaches may represent viable alternatives to open surgery. Nevertheless, evidence remains limited, underscoring the need for additional clinical experience and comparative studies.

This study presents two institutional cases of thoracic SM treated using UBE, comparing their clinical, radiological, and surgical outcomes with previously reported cases. The goal is to evaluate the feasibility, safety, and potential advantages of biportal endoscopic surgery for thoracic intradural extramedullary meningiomas, discussing patient selection, technical considerations, and limitations relative to conventional approaches. We present this article in accordance with the CARE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-2026-1-0018/rc).

Case presentation

Materials and methods

This is a retrospective, descriptive case series at a single tertiary referral center. Two consecutive patients diagnosed with thoracic intradural extramedullary meningiomas and treated with UBE were included. Selection criteria were clinical symptoms, radiological confirmation of an intradural extramedullary lesion, and suitability for minimally invasive endoscopic surgery as determined by the neurosurgical team. No diagnostic challenges were encountered, as radiological findings were characteristic of thoracic intradural extramedullary meningiomas in both cases. During the study period, two patients with thoracic intradural extramedullary meningiomas were treated using the UBE approach at Hospital Regional “1º de Octubre”, and both cases were included in this series. No additional patients meeting the inclusion criteria were excluded. During the same period, one patient with an intradural schwannoma was also treated using the UBE technique; however, this case was not included because the present study specifically focused on thoracic intradural extramedullary meningiomas. Prior to applying the UBE approach for intradural tumors, the surgical team had accumulated experience with this technique primarily in degenerative spine pathology.

Preoperative evaluation

All patients underwent comprehensive neurological examinations and spinal magnetic resonance imaging (MRI), including T1-, T2-, and contrast-enhanced fat-suppressed T1-weighted sequences. Imaging assessed tumor location, size, relation to the spinal cord, degree of canal compromise, and features suggestive of meningioma. Computed tomography (CT) was used selectively to evaluate bony anatomy and exclude calcification when indicated.

Case 1

A 56-year-old female patient presented with a subacute and progressively worsening neurological syndrome that began in April 2025 with numbness of the right lower extremity, initially involving the foot and ascending to the knee, later progressing to the thoracic sensory level. In late July, the patient experienced a fall from standing height, followed by exacerbation of paresthesias in the right lower limb and new contralateral sensory involvement, accompanied by difficulty maintaining upright posture and ambulation, as well as fecal incontinence. Neurological examination revealed preserved mental status, normal strength in the upper extremities and right lower extremity, mild weakness (4/5) in the left lower extremity, and bilateral hypoesthesia from L2 to L5. Preoperative neurological assessment estimated a mJOA score of 13/18, reflecting moderate motor and sensory deficits. Spinal MRI demonstrated a well-circumscribed, homogeneous intradural extramedullary lesion at the T2–T3 level, the lesion appeared hypointense on both T1- and T2-weighted sequences and demonstrated marked, homogeneous enhancement on contrast-enhanced T1-weighted images with fat suppression. Measuring approximately 20 mm × 8 mm × 14 mm, producing significant mass effect with nearly 80% spinal canal compromise and spinal cord compression, findings highly suggestive of a thoracic spinal meningioma.

Symptom onset occurred in April 2025 with progressive sensory deficits, followed by neurological deterioration in July 2025, leading to surgical intervention shortly after radiological diagnosis. Postoperative clinical and radiological follow-up was conducted at 3 months.

Alternative therapeutic options, including conventional open microsurgical resection, were considered; however, a minimally invasive unilateral biportal endoscopic approach was selected based on tumor location, patient condition, and surgeon expertise.

Case 2

A 73-year-old female patient presented with a chronic and progressive clinical course beginning in 2023, characterized by bilateral lower extremity pain associated with gait limitation and impairment of activities of daily living, along with ascending hypoesthesia reaching the thoracic level. On examination, the patient was alert with preserved higher mental functions (Glasgow Coma Scale score of 15), and cranial nerve evaluation was unremarkable. Motor examination demonstrated full strength in all extremities, with hyperreflexia and bilateral positive Babinski signs in the lower limbs, as well as positive Lasègue and Bragard maneuvers. Sensory examination revealed bilateral hypoesthesia, paresthesias, and radicular-type pain involving the T9–L4 dermatomes. No cerebellar dysfunction or meningeal signs were identified. Preoperative neurological assessment estimated a modified Japanese Orthopaedic Association (mJOA) score of 12/18, indicating moderate neurological impairment prior to surgery. Spinal MRI demonstrated a well-circumscribed, homogeneous intradural extramedullary lesion. The lesion appeared hypointense on both T1- and T2-weighted sequences and demonstrated marked, homogeneous enhancement on contrast-enhanced T1-weighted images with fat suppression. Measuring approximately 5 mm × 7 mm × 6 mm at the T9–T10 vertebral level, producing mass effect on the spinal cord with an estimated 25% compromise of the spinal canal, findings highly suggestive of a thoracic spinal meningioma

The patient experienced progressive symptoms beginning in 2023, with gradual neurological deterioration leading to surgical treatment following confirmatory MRI. Clinical and radiological follow-up was performed at 3 months postoperatively.

Alternative surgical approaches, including open posterior microsurgical resection, were considered during preoperative planning; however, a unilateral biportal endoscopic approach was chosen to minimize soft tissue disruption while achieving adequate decompression.

Procedure

Instruments and position

The patient was placed under general anesthesia with orotracheal intubation and positioned in the prone position with reverse Trendelenburg on thoracopelvic bolsters. The head was secured on a padded headrest. Fluoroscopic localization of the surgical level was performed using a C-arm, and skin marking was completed accordingly. Standard surgical skin preparation with povidone-iodine solution was performed, followed by routine sterile draping. Based on preoperative planning and precise lesion localization, two left-sided paramedian skin incisions were made: a 2-cm cranial incision and a 1-cm caudal incision, separated by approximately 1 cm. The cranial incision was used as the working portal, while the caudal incision served as the endoscopic viewing portal.

UBE approach

Intraoperative neurophysiological monitoring was employed in both cases, including continuous somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs), to ensure real-time assessment of spinal cord integrity during tumor dissection and resection. No significant intraoperative signal changes were observed.

After skin and fascial incision using a No. 10 scalpel, a 30° high-definition spinal endoscope was introduced through the viewing portal, as shown in Figure 1. Continuous saline irrigation was established at a pressure of 25–30 mmHg (corresponding to an approximate height of 70–100 cm above the operating table) using 0.9% normal saline. Through the working portal, sequential dilators and muscle retractors were inserted, and blunt dissection of the paraspinal musculature was performed.

Figure 1 Surgeon positioning during a biportal endoscopic approach. Illustration courtesy of Juan Pablo Acosta Vázquez.

A 90° plasma radiofrequency probe was used to achieve superficial dissection of the bony surface and to clearly identify the lamina at the superior and inferior margins of the intervertebral space. Subsequently, a high-speed Stryker burr and a No. 2 Kerrison rongeur were used to perform a hemilaminectomy along the inferior edge of the cranial lamina and the medial portion of the inferior articular process. This exposure allowed identification of the superior and inferior insertions of the ligamentum flavum, which was then resected according to the level of the lesion documented on preoperative MRI, until adequate exposure of the dura mater was achieved (Figure 2).

Figure 2 Intraoperative images showing the surgical steps. (A,B) Laminectomy performed using a high-speed Stryker drill and Kerrison rongeur. (C) Exposure of the dura mater with identification of anatomical structures. (D) Durotomy. (E) Resection of the lesion. (F) Histopathological image showing a meningothelial pattern with whorl formation (hematoxylin and eosin staining; original magnification, ×20).

Tumor resection and closure

A 2-cm durotomy was performed using a No. 11 scalpel, revealing a soft, pearly intradural extramedullary lesion adherent to the posterolateral dural margin and causing compression of the thoracic spinal cord. The lesion was carefully dissected and completely removed using a blunt hook, separating it from the external surface of the spinal cord and the inner surface of the dura mater.

At the completion of tumor resection, no active bleeding was observed at the surgical site under endoscopic visualization. After tumor resection, primary dural closure was performed endoscopically using interrupted sutures under continuous visualization through the working portal. Careful control of irrigation flow was maintained to avoid excessive cerebrospinal fluid egress and to preserve adequate visualization of the dural edges. A key technical aspect is maintaining a stable working corridor and using long endoscopic needle holders to facilitate precise needle passage through the dural margins. Compared with conventional open microsurgical techniques, endoscopic dural closure requires careful instrument triangulation and controlled movements to avoid excessive traction on the spinal cord. When necessary, fibrin sealant was applied to reinforce the dural closure and reduce the risk of postoperative cerebrospinal fluid leakage (Figures 2-4).

Figure 3 Minimally invasive unilateral biportal endoscopic approach and surgical wound for resection of a thoracic intradural meningioma. (A-D) Preoperative MRI showing a well-defined intradural extramedullary lesion at the T9–T10 level with mild spinal cord compression and no intramedullary edema. (E-H) Postoperative MRI and CT images demonstrating complete tumor resection and adequate spinal canal decompression. (I) Three-dimensional CT reconstruction showing preservation of posterior elements. (J) Postoperative surgical wound. CT, computed tomography; MRI, magnetic resonance imaging.

Figure 4 Preoperative and postoperative MRI findings of a thoracic intradural meningioma. (A-D) Preoperative MRI and CT showing an intradural extramedullary mass at the T2–T3 level with severe spinal cord compression. (E-H) Postoperative MRI and CT demonstrating complete tumor resection and adequate spinal canal decompression. (I) Three-dimensional CT reconstruction showing preservation of the posterior elements. CT, computed tomography; MRI, magnetic resonance imaging.

The subcutaneous tissue was closed with continuous sutures using 1-0 Vicryl, and the skin was closed with interrupted Sarnoff sutures using 2-0 nylon. The surgical wound was dressed in a sterile fashion, and the procedure was concluded. Both patients were extubated in the operating room and transferred to recovery awake, with preserved motor function of the lower extremities, no reported pain. The operative time was 4 hours in the first case and 3.30 hours in the second case. Estimated blood loss was 70 cc and 90 cc, respectively.

Technical pearls for endoscopic dural closure using the unilateral biportal approach

Endoscopic dural closure represents one of the most technically demanding steps of intradural endoscopic surgery.

• Maintain stable visualization: continuous but low-pressure irrigation should be maintained to preserve a clear surgical field while avoiding excessive cerebrospinal fluid egress.
• v Optimize portal triangulation: proper positioning of the viewing and working portals facilitates adequate instrument triangulation and allows controlled manipulation during dural suturing.
• v Use long endoscopic needle holders: specialized long instruments improve maneuverability and allow precise needle passage through the dural edges under endoscopic visualization.
• v Minimize spinal cord traction: suturing should be performed with gentle and controlled movements, working from the lateral dural edge toward the midline to reduce the risk of spinal cord manipulation.
• v Reinforce when necessary: application of fibrin sealant after primary suturing may help reinforce dural closure and reduce the risk of postoperative cerebrospinal fluid leakage.

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 Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patients 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.

Results

Both patients underwent successful resection of an intradural extramedullary lesion, with a hospital stay of 6 and 7 days, and no perioperative complications. Postoperatively, both patients demonstrated clear clinical improvement, with progressive resolution of preoperative symptoms. Case 1 showed an increase in mJOA score from 13/18 preoperatively to 17/18 at 3-month follow-up, reflecting significant recovery in motor and sensory functions. Case 2 improved from a preoperative mJOA of 12/18 to 16/18, indicating marked neurological improvement. At 3-month outpatient follow-up, both patients demonstrated clear postoperative neurological improvement with reduction of preoperative symptoms and no new neurological deficits. Perioperative characteristics and clinical outcomes are summarized in Table 1. Operative time was 3.30 and 4 hours for cases 1 and 2, respectively, with an estimated blood loss of 70 and 90 mL. Both patients underwent GTR without intraoperative or perioperative complications. Postoperative imaging studies, including CT and MRI, showed adequate decompression of the spinal canal. A hemi-laminotomy was performed while preserving the spinous process and facet joint. Follow-up MRI confirmed complete removal of the intradural extramedullary tumor with sufficient spinal canal decompression. Histopathological analysis revealed a WHO grade I meningioma. Clinical and radiological outcomes were systematically assessed during outpatient follow-up visits at 3 months after surgery.

Discussion

Spinal intradural extramedullary tumors represent a significant proportion of intraspinal neoplasms, with meningiomas being the most common histological subtype, particularly within the thoracic spine (1,2). These tumors are typically slow-growing, benign lesions (WHO grade I) that predominantly affect middle-aged and elderly women and frequently present with progressive myelopathy secondary to chronic spinal cord compression (1-3). Given their favorable biological behavior, the primary therapeutic goal is GTR with maximal neurological preservation.

Historically, thoracic SM have been managed through conventional open posterior approaches, including laminectomy or hemilaminectomy with microsurgical resection. These techniques have demonstrated high rates of complete tumor removal and durable tumor control (3,7). However, open approaches are associated with relevant approach-related morbidity, such as extensive paraspinal muscle dissection, increased blood loss, postoperative pain, longer hospital stay, and potential postoperative spinal instability—factors that are particularly relevant in elderly patients, who constitute the majority of this population (3,5).

In response to these limitations, MISS techniques have been progressively adopted for IDEM tumors. Tubular and unilateral hemilaminectomy approaches have shown comparable rates of GTR and neurological improvement when compared with open surgery, while significantly reducing muscle injury, intraoperative blood loss, and postoperative recovery time (5,6). Furthermore, tailored minimally invasive approaches, including transpedicular and posterolateral techniques, have expanded the surgical armamentarium for ventrally or ventrolaterally located thoracic IDEM tumors, maintaining oncological effectiveness while minimizing collateral tissue damage (7).

More recently, advances in spinal endoscopy have led to the application of endoscopic techniques for intradural pathology. Uniportal endoscopic approaches have been described; however, their use remains limited by restricted instrument maneuverability and a steep learning curve, particularly in complex intradural procedures. UBE has emerged as a promising alternative, offering independent visualization and working portals, improved ergonomics, enhanced illumination, and magnification comparable to microscopic surgery, while preserving the principles of minimally invasive access (10-12).

Despite its theoretical advantages, the application of UBE for thoracic IDEM meningiomas remains in an early stage. To date, and according to the currently available literature, only a limited number of reports have specifically described the resection of thoracic intradural extramedullary meningiomas using a UBE technique (8-10). Shao et al. reported the first technical application of UBE for a thoracic spinal meningioma, demonstrating complete tumor resection, adequate spinal cord decompression, minimal blood loss, and favorable neurological recovery (8). Subsequently, Huang et al. described the successful use of UBE in a high-grade thoracic spinal meningioma, further supporting the feasibility and safety of this approach even in more complex pathological scenarios (9). More recently, Peng et al. presented a case series and technical report highlighting the versatility of UBE for thoracic IDEM tumors, emphasizing reduced surgical trauma, preservation of posterior spinal elements, and rapid postoperative recovery, A brief narrative overview of previously reported cases is presented to contextualize our findings; however, this was not intended to represent a systematic review of the literature (10).

In this context, the present study contributes meaningful additional evidence by reporting two institutional cases of thoracic SM treated using UBE surgery. Both patients experienced favorable postoperative outcomes, including short hospital stays 6 and 7 days, significant clinical improvement, and radiological confirmation of complete tumor resection with adequate spinal canal decompression. It should be emphasized that neurological recovery in these patients is primarily attributable to adequate spinal cord decompression following tumor resection, rather than to any specific advantage of the endoscopic technique itself. However, these hospitalization durations are comparable to those reported in conventional microsurgical series, and therefore should not be interpreted as evidence of superiority of the UBE approach. Importantly, posterior elements such as the spinous process and facet joints were preserved, and postoperative imaging demonstrated satisfactory decompression without evidence of instability. Histopathological analysis confirmed WHO grade I meningiomas in both cases. Our series adds to the limited existing evidence by demonstrating reproducible clinical and radiological outcomes using UBE in thoracic SM

Although the number of reported cases remains limited, the consistency of favorable outcomes across published reports and the present series suggests that UBE may represent a technically feasible minimally invasive approach for selected thoracic intradural extramedullary meningiomas. However, the currently available evidence remains limited to isolated case reports and small case series. Therefore, careful patient selection, detailed anatomical assessment, and advanced endoscopic expertise are essential. Larger series and comparative studies are required to further define the role of UBE relative to established open, tubular, and uniportal endoscopic techniques (Table 2).

Patient-reported outcome measures were not formally collected due to the retrospective nature of this case series; however, both patients subjectively reported significant improvement in daily activities during follow-up.

At our institution, UBE technique has been widely utilized for the treatment of degenerative spinal diseases, allowing the surgical team to gain substantial experience with endoscopic spinal anatomy, continuous irrigation systems, and biportal instrument handling. This accumulated experience has facilitated the development of an institutional initiative aimed at evaluating the feasibility of UBE in selected spinal tumor cases. Based on our familiarity with the technique and careful patient selection, we consider that UBE may represent a viable minimally invasive alternative for the management of certain intradural extramedullary tumors, offering adequate visualization and decompression while preserving posterior spinal structures.

In the present series, both tumors were relatively well circumscribed, which facilitated safe resection through the unilateral biportal endoscopic approach. However, it is noteworthy that in one of our cases the lesion occupied approximately 80% of the spinal canal, yet complete resection and adequate decompression were achieved without neurological deterioration. These findings suggest that, in carefully selected patients and with adequate surgical experience, the unilateral biportal endoscopic technique may represent a safe and reproducible minimally invasive option. Nevertheless, tumor size and anatomical characteristics should always be carefully considered, as larger or more complex lesions may require alternative surgical strategies.

One of the main limitations of this report is the small sample size, as only two cases are presented. Therefore, the findings should be interpreted with caution and primarily as a demonstration of technical feasibility rather than definitive evidence regarding the effectiveness of the unilateral biportal endoscopic approach for intradural tumors. Another limitation of this report is the relatively short follow-up period of 3 months, which restricts the ability to assess long-term clinical outcomes, potential tumor recurrence, and durability of decompression. Longer follow-up and larger case series will be necessary to better evaluate the long-term safety and effectiveness of this approach.

Conclusions

UBE is an emerging minimally invasive surgical technique that may offer a feasible approach for selected cases of spinal intradural extramedullary meningiomas. The clinical and radiological outcomes observed in the present series, together with the limited but consistent evidence available in the literature, suggest that UBE can achieve complete tumor resection with effective spinal cord decompression, preservation of posterior spinal elements, and minimal approach-related morbidity. These advantages are especially important in a predominantly elderly patient population, in whom reducing soft tissue injury, postoperative pain, and the risk of spinal instability is of paramount importance.

Nevertheless, the application of UBE for intradural spinal pathology remains at an early stage of development. Therefore, its adoption as a standard therapeutic strategy should be approached cautiously, with careful patient selection and performance by surgical teams experienced in advanced endoscopic spine techniques.

The UBE approach may represent a feasible minimally invasive alternative for selected intradural extramedullary tumors. However, given the limited number of cases presented, these findings should be considered preliminary, and further studies with larger patient cohorts are required to better define its safety, indications, and long-term outcomes.

Further prospective studies, larger case series, and comparative analyses with conventional open surgery and other minimally invasive approaches are required to strengthen the evidence base, refine indications, and more clearly define the role of UBE in the comprehensive treatment of SM.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-2026-1-0018/rc

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-2026-1-0018/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-2026-1-0018/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 ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patients 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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