1. Background and Importance 
Neurofibromatosis Type 1 (NF1), with a prevalence of 1 in 3000, is among the most frequently observed autosomal dominant disorders [1]. The NF1 gene was discovered to be on chromosome 17q11.2 [2]. Nearly 50% of NF1 cases are attributable to novel mutations [3]. Rare tumors, such as pheochromocytoma, brain tumors, and malignant peripheral nerve sheath tumors are more common in NF1. However, those tumors which frequently spread into the lung, breast, and colon, are not usually present in these patients [4]. Therefore, mass-like lesions are more likely to be malignant in NF1 patients. Spinal deformities may appear alongside NF1 being categorized into two types based on radiographic evaluation: non-dystrophic and dystrophic [5]. The former is like idiopathic scoliosis while the latter has its own distinctive features (such as transverse process spindling, vertebral wedging, and intervertebral foraminal enlargement, etc). Additionally, scoliosis is the most frequent skeletal manifestation in affected NF1 patients, with an incidence rate of 10% to 71% [6, 7]. Dural ectasia, spondylolisthesis, and defective pedicles are infrequently seen in NF1 patients. Therefore, awareness of these deformities contributes to an early diagnosis and optimization of the treatment [8]. The present research reports on a 62-year-old NF1 female patient with a large intrathoracic mass which was diagnosed accidentally. 


2. Case Presentation
A 62-year-old female, a known case of NF1, was admitted to Poursina Hospital, Rasht, Iran due to an unusual chest X-ray and chest CT showing a thoracic mass, while she was hospitalized and under observation for dyspnea and a probable COVID-19 diagnosis during the coronavirus pandemic in Iran. She had back pain for two years, which was relieved by using medication. Moreover, no history of trauma was reported. However, physical examination revealed extensive café-au-lait spots, cutaneous neurofibromas, and axillary freckling which were consistent with the diagnosis of NF1. Muscle force and neurological examination were normal. The patient had a family history of neurofibromatosis as her daughter had NF1 as well. Chest radiography showed a huge mass and scoliosis (Figure 1A). A 17 cm homogeneous cystic mass with a thin wall in the right paravertebral area, spreading into the spinal canal via the T4-5-6 neural foramen, was revealed in chest CT (Figure 1B) and MRI (Figure 1C).

To prevent the progressive deterioration of pain and spine deformity, sampling of the mass and surgical stabilization of the spine were performed (Figure 2).

After one year of follow-ups, she showed no sign of dyspnea, and the back pain was reduced.
Under general anesthesia, a long-level posterior fusion from T3 to T7 using pedicle screws was performed. During the procedure, it was not possible to set the pedicle screws on the right side of T6 and the two sides of the T4-T5 pedicles.

3. Discussion
The extension of the dural sac characterizes dural ectasia which most frequently occurs in the lumbosacral spine [9]. Although dural ectasia is related to Marfan syndrome, it is usually diagnosed in patients suffering scoliosis, neurofibromatosis, ankylosing spondylitis, and Ehlers-Danlos syndrome [10]. There is a relationship between the widening of the dural sac, known as dural ectasia, and the dystrophic alteration seen in neurofibromatosis type 1. Dural ectasia appears as meningocele through larger neuroforamina, causing bone degradation and organ displacement [11]. An association has been observed between meningioma and spinal nerve fibroma with neurofibromatosis type 1 that can protrude laterally and erode the neuroforamina [11]. In addition, because the thoracic region muscles are weaker and the pressure gradient of the subarachnoid space is higher than that of the thorax, lateral dural ectasia is commonly seen in this region. Moreover, it is essential to differentiate dural ectasia from other tumors, such as neuroblastoma, neurofibroma, and ganglioneuroma [12].
Central posterior vertebral body erosion and wedging, pedicle erosion, foraminal enlargement, and kyphosis are included in classic radiologic findings. Angular deformities (typically less than six levels of vertebrae), fractures of vertebrae, and dislocations are among the consequences of progressive vertebral body erosion [11]. Since the spinal canal is widened, neurologic deficit rarely occurs. Furthermore, due to the adverse effects of spinal cord compression, there is a chance of paraparesis or pain [13]. Spinal abnormalities grow and evolve into a condition known as “modulation” as the disease progresses. Surgical intervention is performed on patients with spinal deformities or symptomatic patients due to spinal cord compression and mediastinal structures. Early posterior fixation and fusion are required for the reduction and prevention of severe deformities and complications [11].

4. Conclusion
Neurofibromatosis type 1 manifests as dura weakness and results in focal enlargement, which is termed dural ectasia. Despite the fact that dural ectasia is an uncommon and benign condition, operation is often required for symptomatic, developing lesions. 


Ethical Considerations
Compliance with ethical guidelines
Written informed consent was obtained from the patient.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
Conception, design, drafting the article: Mahsa Pakseresht Mogharab; Data collection: Mahsa Pakseresht Mogharab, Amin Naseri; Critically revising the article: Amin Naseri, Mahsa Pakseresht Mogharab; Reviewing submitted version of the manuscript, data analysis, and interpretation, approving the final version of the manuscript: All authors.

Conflict of interest
The authors declared no conflict of interest.



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