Primary intratracheal schwannoma resected during bronchoscopy using argon plasma coagulation

Abstract

A 63-year-old man presented with intermittent, progressively worsening dyspnoea associated with cough and blood-tinged sputum. Initial work-up showed left axis deviation on ECG, chest X-ray with an elevated left hemidiaphragm and a non-contrast CT chest that showed a multilobulated mass in the proximal trachea. Bronchoscopy showed a whitish-appearing lesion, which was then sampled and partially resected with pathology showing a schwannoma with no malignant cells. He felt partial relief post procedure; however, he presented a month later with similar symptoms of dyspnoea and a repeat CT scan showed enlargement of the mass in the same location. The patient underwent another flexible bronchoscopy and resection with argon plasma coagulation (APC)/electrocautery snare. APC/electrocautery is an effective interventional bronchoscopy technique that can be used to resect endoluminal lesions or extraluminal lesions that have infiltrated into the airway using flexible/rigid bronchoscopy. It is more cost-effective, safe, works well with vascular lesions and achieves excellent haemostasis as compared with Nd:YAG lasers.

Background

Primary tracheal tumours are rare. Primary tracheal tumours can either be benign or malignant with malignant being more common. Of the malignant tumours, the most common are squamous cell carcinomas and adenoid cystic carcinomas.¹ Benign tracheal tumours are usually haemangiomas, hamartomas or papillomas.

We present a case of a 63-year-old man with a primary intratracheal benign schwannoma resected with bronchoscopy by argon plasma coagulation (APC) and electrocautery.

Case presentation

A 63-year-old man presented to the emergency department (ED) complaining of dyspnoea that had been waxing and waning for the past 2–3 months. Initially, the dyspnoea was on exertion only, brought on after walking about 2–3 miles. However, the patient started having worsening dyspnoea over several weeks even at rest. It was exacerbated by lying flat and improved on sitting upright. He also endorsed a cough with intermittent blood-tinged sputum. The patient denied any associated chest pain, palpitations or lower extremity swelling or paroxysmal nocturnal dyspnoea. He denied any fevers, chills, wheezing or stridor. His medical history included hypertension, dyslipidaemia and chronic obstructive lung disease (chronic obstructive pulmonary disease). His past surgeries included a haemorrhoidectomy and hernia repair. He admitted to smoking cigars for many years as well as occasional alcohol use. He has a history of cocaine abuse but had abstained for the last 17 years.

Investigations

On arrival in the ED, his vital signs were temperature 97.5^◦F, heart rate 72/min and blood pressure 126/80 mm Hg. He was saturating at 95% on room air, with a respiratory rate of 20/min. Initial laboratory work was unremarkable except for an elevated haematocrit of 51.5 (which was his baseline for more than a year). His ECG showed sinus rhythm with left axis deviation. An initial chest X-ray obtained in the ED showed a chronically elevated left hemidiaphragm (also present for more than a year) associated with ipsilateral mild basilar atelectasis. (figure 1). A CT scan was done, which showed a multilobulated mass in the proximal trachea. A prior CT scan 1 year ago showed a small density visible in the same area as the mass; however, this had not been addressed at that time.

Figure 1.

Chest X-ray showing an elevated left hemidiaphragm associated with ipsilateral mild basilar atelectasis.

Treatment

Pulmonology was consulted after the updated imaging. A bronchoscopy was done via a laryngeal mask airway (LMA) so as not to disrupt the mass. This showed a large whitish mass emanating from the 9 o’clock position of the trachea about 2 cm below the vocal cords (figure 2). This lesion appeared to move back and forth with the respiratory cycle and was obstructing about 90% of the airway. A transbronchial needle aspiration (TBNA) was obtained to rule out malignancy quickly being mindful of the risk of bleeding. Using a combination of APC and electrocautery snare, a piece of the mass was removed and retrieved with forceps and suction. On removal, the mass was found to be firm.

Figure 2.

(A) Bronchoscopy image showing mass at the 9 o’clock position of the trachea about 3 cm below the vocal cords. (B) Bronchoscopy image showing mass in the proximal trachea. (C) Bronchoscopy image showing removal of large piece of mass with forceps and (D) argon photocoagulation and electrocautery.

Cytological analysis of the TBNA revealed ciliated columnar epithelium and was negative for malignant cells (figure 3). The surgical pathology confirmed the mass to be a schwannoma. Immunoperoxide stain performed on the mass showed positivity for S-100 and was negative for all the other stains including desmin, smooth muscle actin and cytokeratin. The patient went home with instructions to follow-up the next week but unfortunately did not.

Figure 3.

(A) Medium-power view of Antoni A (hypercellular), Antoni B (hypocellular), Verocay body (centre) and thickened blood vessels. (B) High-power view of Verocay body. (C) S-100 immunostain showing strong diffuse positivity. (D) ki-67 immunostain showing low proliferative activity (<5%).

Outcome and follow-up

One month later, the patient presented again with dyspnoea on exertion. A CT scan showed persistence of tracheal lesion. Another bronchoscopy via LMA was done that showed some growth of the mass. It was removed in totality with the electrocautery snare followed by APC of the bed of the stump (figure 4). The mass was removed with combination of forceps and placing the patient in Trendelenburg position. The distal airways were notable for tracheobronchomalacia extending to the subsegmental airways as well.

Figure 4.

(A) Bronchoscopy image showing mass below the vocal cords. (B) Image showing completely removed mass. (C and D) Bronchoscopy image after complete removal of mass and also showing tracheobronchomalacia.

The patient’s follow-up has been suboptimal. He did present for routine follow-up about 8 months out. At that time, a repeat surveillance bronchoscopy was advised, but the patient was not agreeable. Therefore, a CT scan was done that showed a normal-appearing trachea with no regrowth of the mass. Also, his symptoms of dyspnoea on exertion and orthopnoea had resolved. Follow-up beyond this was not possible despite several attempts.

Discussion

Primary tracheal tumours are relatively uncommon. About two-thirds of these tumours are malignant or of intermediate malignancy. The remaining one-third include a heterogeneous group of benign tumours including neurogenic tumours.^{1 2} Neurogenic tumours include neurofibromas and schwannomas (also known as neurilemmomas). These tumours are rare and may present at any age group. Schwannomas typically arise from neural crest cells that encapsulate the nerve sheath and are much less common than neurofibromas. They usually occur in the head, neck, retroperitoneum, extremities and mediastinum.^3–5 These tumours are extremely rare in the trachea being more commonly seen in the lungs and bronchi.⁶

Intratracheal tumours are usually asymptomatic in the early stages. However, once more than 50% of the trachea is occupied, patients start having non-specific symptoms of cough, hoarseness and dyspnoea. It could also present as an emergency if the patient has inspiratory stridor with central airway obstruction.⁷ Due to the non-specific nature of these symptoms, patients are usually misdiagnosed with and treated for asthma prior to evaluation of the airways. Intratracheal masses should be considered in patients with dyspnoea and stridor and in patients with asthma who are refractory to usual treatment.

In our patient, the mass was present in the proximal part of the trachea and below the vocal cords with no extension in the bronchi. In a literature review of 51 cases of tracheal schwannomas, it was found that the majority of the tumours occurred in the distal third of the trachea, followed by the proximal and then the middle third of the trachea.⁸

Management of primary tracheal schwannoma should take into consideration factors such as size of the tumour, extratracheal component and cardiopulmonary status of the patient. Although surgical resection and tracheal reconstruction is the standard management of endobronchial tumours, endoscopic laser resection has also been successfully used in the management of benign tumours. Among the 51 patients in the literature review, 19 patients underwent endoscopic resection of the mass and 29 received surgical resection.⁸

After the development of special endoscopic probes, APC was introduced to flexible endoscopy in 1991 in Germany by Grund et al.⁹ The APC working principle is that when a high-voltage electric current is passed along the probe, argon gas expelled from the probe comes in contact with the electric current, becomes ionised and conducts an electric current that results in superficial thermal coagulation of the tissue.¹⁰

The depth of penetration of thermal energy is about 2 to 3 mm. Thus, APC is most useful for the treatment of superficial/flat lesions and highly vascular ones. Compared with APC, Nd:YAG laser has deeper penetration of tissue. Despite the differences in penetration, extensive bronchial tumours have been treated successfully with the help of APC/electrocautery.¹¹

A retrospective study of 60 patients with endobronchial tumours treated with endobronchial APC concluded that APC is a simple, low-risk procedure for treatment of symptomatic airway obstruction and haemoptysis as compared with other interventional endobronchial techniques. This study was one of the first to report the feasibility and effectiveness of APC for debulking of endoluminal tracheobronchial lesions through flexible bronchoscope.¹²

APC is a relatively low-cost technique with excellent safety profile. It can be used with either the flexible or rigid bronchoscope under conscious sedation with the former and general anaesthesia with the latter. APC is a compliment to well-known techniques, increasing the options for interventional bronchoscopy.

Rigid bronchoscopy is probably the best conduit for managing endotracheal lesions, although bronchoscopy via LMA is a viable option. However, an important point to note is that since the lesion was in the upper trachea, in the immediate subglottis, there was no landing space for the rigid scope. Therefore, a rigid bronchoscope was not used and bronchoscopy via LMA was thought to be a better option.¹³

Recurrence of the tumour after endoscopic resection is common and has been previously reported.^{14 15} Usually, for local recurrence following endoscopic resection, surgery is chosen as the next best alternative.

Learning points.

• Schwannomas typically arise from neural crest cells that encapsulate the nerve sheath and are much less common than neurofibromas and are usually found in the head, neck, retroperitoneum, extremities and mediastinum.

• Management of primary tracheal schwannoma should take into consideration factors such as size of the tumour, extratracheal component and cardiopulmonary status of the patient.

• Argon plasma coagulation (APC) and electrocautery is an effective interventional bronchoscopy technique that can be used to resect endoluminal lesions or extraluminal lesions that have infiltrated into the airway using flexible/rigid bronchoscopy.

• APC and electrocautery is more cost-effective and has a better safety profile as compared with the Nd:YAG laser.

• APC and electrocautery works well with vascular lesions and helps achieve excellent haemostasis as compared with Nd:YAG lasers.