Primary endobronchial schwannomas are extremely uncommon, constituting approximately 2% of benign tracheobronchial tumors1. Because of the slow growing nature of these tumors, they rarely cause symptoms when small and are often presented late1. However, the patient may be presented with cough, dyspnea, and pneumonia depending on the location and size of the tumor2. For the treatment of these benign endobronchial tumors, bronchoscopic removal has been recently reported to be useful3,4. However, there is limited information on the bronchoscopic removal of endobronchial schwannoma. We present a case of endobronchial schwannoma that was successfully managed by rigid bronchoscopy with argon plasma coagulation (APC) in a 44-year-old woman.

A 44-year-old woman was referred to our clinic with a left main bronchus nodule shown in her chest computed tomography (CT) scan. She underwent laparoscopic low anterior resection, liver wedge resection, and cholecystectomy for rectal cancer with liver metastasis approximately 9 months ago. She had no respiratory symptoms and a normal lung sound on physical examination. Her chest radiograph and pulmonary function tests were normal. Chest CT scan revealed a 1.1×1.9 cm endobronchial mass in the left main bronchus without obstructive atelectasis and lung parenchymal invasion (Figure 1A). Fiberoptic bronchoscopy revealed a 1.5 cm sized hypervascular and polypoid mass with no mucosal destruction and causing a near total obstruction of the left main bronchus at 1 cm below the carina (Figure 1B). Biopsy showed a benign vascular lesion which is suspected to be cavernous hemangioma. Rigid bronchoscopy was performed under general anesthesia for treating a benign endobronchial tumor. APC was applied before tumor removal for coagulation and the tumor was then removed by a rigid bronchoscope tip. After removal, APC was applied again for bleeding control (Figure 1C). There were no procedure-related complications. The microscopic examination revealed fascicles of spindle cells and palisanding nuclei. The nuclei were positive for S-100 protein, whereas results of desmin and smooth muscle actin were negative by immunohistochemical staining. In addition, no malignant transformation was identified (Figure 2). The postoperative course was uneventful, and the patient was discharged on the first post-procedural day.

The patient was monitored in an outpatient clinic and there was no recurrence for the 4-month follow-up period (Figure 1D).

This is a case report of endobronchial schwannoma that was completely removed by rigid bronchoscopy with APC.

Bronchial wall schwannoma was first described in 1951 by Straus and Guckien5 as an extremely rare form of bronchial benign neurogenic tumor. Schwannomas are designated as neoplasms of Schwann cell myelin that are often histologically benign. They are usually well circumscribed and are encapsulated masses arising from peripheral and cranial nerves6.

Kasahara et al.2 reviewed 50 cases of pulmonary neurilemmomas reported in Japan and classified them as central and peripheral types according to their localizations. Of these 50 cases, 25 were classified as central (13 at trachea, 12 at bronchus), 13 were peripheral (intrapulmonary lesions), and 12 were combined (central and peripheral lesions). Most cases of the central type had symptoms, such as dyspnea, wheezing, cough, and pneumonia except for 3 bronchial lesion cases that had no symptoms. The most common size of the central type tumors was 1 cm to 3 cm in diameter. In our case, although the tumor was located centrally (left main bronchus) with a size of 1.5 cm in diameter, there were no respiratory symptoms.

Radiologically, the tumor appears as a round, ovoid, or lobulated homogenous mass with sharp borders7. In our case, we also found the round nodule on her chest CT scan. However, we could not differentiate this tumor from other endobronchial tumors. A CT scan could reveal the tumor and show its size and the extent to which the tumor is confined within the tracheobronchial lumen without evidence of adjacent invasion, findings that may be helpful for bronchoscopic intervention or surgery.

Surgical resection has been the standard treatment for the tracheobronchial tumors. Although surgical resection should be performed conservatively, a thoracotomy is usually required2,8. Recently, bronchoscopic intervention has been shown to be a safe and effective tool for the treatment of a benign tracheobronchial tumor1,3. Many different interventional bronchoscopic techniques has been used, such as resection by forceps, APC, Nd-YAG laser, cryotherapy or the use of a snare9. These bronchoscopic interventions may avoid the complications and morbidities associated with surgery. APC is a non-contact thermal treatment using ionized argon gas jet flow to conduct electrons9. A cheaper equipment compared to the Nd-YAG laser and the ease of using the instrument and flexible applicators are strong advantages of using APC9. Although the effect of APC are superficial compared with that of an Nd-YAG laser, APC combined with mechanical debulking could be an effective tool for removing the endobronchial tumors9,10. In our case, we applied APC to coagulation before and after tumor removal and for the vaporization of residual tumor after mechanical debulking using the tip of rigid bronchoscopy.

In conclusion, primary endobronchial schwannoma is a rare disease that can occur without any symptoms. Rigid bronchoscopy with APC can be an effective and safe technique for an endobronchial schwannoma.