Introduction
Ancient schwannomas, first described by Ackerman and Taylor,Reference Ackerman and Taylor1 are benign, slow-growing tumours. Histopathological characteristics consist of diffuse hypocellular areas and degenerative changes indicative of the tumour's prolonged age.
We report a case of an ancient schwannoma of the oesophagus, which had an unusual clinical presentation of stridor due to its large intratracheal component.
Case report
A 40-year-old woman was referred to our hospital with a six-year history of gradually progressive stridor.
Flexible fibre-optic bronchoscopy showed a broad-based, polypoid mass arising from the posterior wall of the trachea. The base of the tumour was located about 3.5 cm from the vocal folds.
The patient had thrice undergone laser excision of the tumour in another ENT centre, but the symptoms of obstruction had recurred after a brief asymptomatic period. Her symptoms had continued to progress, and had become severe. She had therefore been referred to our institution for further management.
The patient denied any history of dysphagia, hoarseness of voice or otalgia. There was no prior history of bronchial asthma.
A high resolution computed tomography (CT) scan revealed a hypodense soft tissue lesion (2.5 × 2.5 × 2.0 cm) in the upper thoracic trachea projecting intraluminally and almost occluding the tracheal lumen. There was loss of the plane between the retrotracheal component of the mass and the oesophagus, suggestive of a locally aggressive lesion with extension to the retrotracheal plane (Figure 1). The distance from the cricoarytenoid joint to the upper surface of the tracheal mass was 3.4 cm, and that from the lower border of the mass to the carina was 3.5 cm.
Fig. 1 Axial computed tomography scan showing the lesion in the tracheal lumen, with retrotracheal extension.
In view of the patient's tracheal tumour with extratracheal spread and recurrence after previous laser therapy, she was taken to theatre for open surgery.
The patient was intubated nasally using a flexible fibre-optic bronchoscope. The patient was placed in the supine position and the trachea exposed using a generous collar incision. With the neck in full extension, the upper mediastinal trachea was elevated into the operative field and the lesion was located using a flexible bronchoscope. The trachea was incised at the site of the lesion and the tumour visualised. The mass was found to have eroded the posterior wall of the trachea, with attachment to the oesophagus. The mass was enucleated from the wall of the oesophagus. The muscular layer of the oesophagus was not involved by the tumour.
The segment of the trachea with the lesion was mobilised by sharp dissection, which was maintained as close to the tracheal wall as possible. Resection of about 3 cm of the trachea was required, and an end-to-end anastomosis was created using interrupted Vicryl sutures.
The post-operative course was uneventful. Fibre-optic bronchoscopy performed on the 10th post-operative day showed a well healed anastomosis. The patient was discharged on the 12th post-operative day.
At the time of writing, the patient had been followed up regularly for the past 18 months, with no evidence of recurrence.
Histopathological findings
Gross examination of the resected mass revealed areas of haemorrhage, congestion and cystic change.
Microscopically, the tumour was composed of Antoni A and Antoni B areas (Figure 2) with numerous Verocay bodies and moderate to marked degenerate atypia. There were areas of increased cellularity with nuclear pleomorphism, alongside areas of hypocellularity. Interlacing fascicles of spindle-shaped cells with eosinophilic cytoplasm and oval to elongated nuclei with fine chromatin and visible nucleoli were seen. There were myxoid changes, hyalinisation, oedema and stromal infiltration of lymphocytes. There were a few multinucleated bizarre cells, and parts of a capsule were present at the periphery. Many congested blood vessels were seen, a few with hyaline collars. No significant mitosis was present in the sections. The tracheal wall showed mild subepithelial chronic inflammation and recent haemorrhage.
Fig. 2 Photomicrograph of the resected mass, showing cellular Antoni A and hypocellular Antoni B areas (H&E; ×50).
Discussion
Ancient schwannoma is a rare variant of schwannoma and is usually located deep in the head and neck. The degenerative changes occurring in this tumour are the result of its long-term progression.Reference Jayaraj, Levine, Frosh and Almeyda2, Reference Dayan, Buchner and Hirschberg3 Schwannomas are extremely rare in the oesophagus; Chatelin and FissoreReference Chatelin and Fissore4 first reported this entity in 1967.
The histopathological features of ancient schwannomas are distinguished from those of malignant schwannomas by the absence of mitoses and the invasive pattern.
The most common symptom of oesophageal schwannoma is dysphagia. Our patient presented with stridor, without dysphagia. Her tumour manifested clinically as stridor due its tracheal extension. A review of previous reportsReference Basoglu, Celik, Sengul and Yildiz5 indicated that oesophageal schwannomas are commonly located in the upper oesophagus and occur frequently in middle-aged women, as in our case.
In almost all reported cases of benign oesophageal schwannoma, the tumour could be enucleated without the need for tracheal resection and anastomosis. Our patient had three sessions of potassium-titanyl-phosphate laser excision prior to referral to our hospital. This, we believe, could have resulted in injury and therefore weakening of the posterior tracheal wall, which facilitated further erosion and extension of the tumour into the tracheal lumen. Park et al. Reference Park, Carrasquillo, Bains and Flores6 have reported a case of benign oesophageal schwannoma requiring oesophagectomy. While tracheal invasion occurs in cases of thyroid and oesophageal malignancies, it is rare in benign tumours. Mizuguchi et al. Reference Mizuguchi, Inoue, Imagawa, Kitano, Kameyama and Ueda7 have reported a case of benign schwannoma of the oesophagus compressing the trachea of a pregnant woman, while Chen et al. Reference Chen, Huang, Wu, Lin and Fang8 have reported a case of oesophageal schwannoma compressing the trachea of a 73-year-old woman, with resulting cough, exertional dyspnoea and progressive dysphagia. Rusch and SchmidtReference Rusch and Schmidt9 have reported a case of successful endoscopic laser resection of schwannoma of the trachea. In most cases of benign schwannoma of the oesophagus, the lesion can be enucleated without the need for oesophageal or tracheal resection. Horovitz et al. Reference Horovitz, Khalil, Verani, Guthric and Cowan10 have reported local recurrence of intratracheal schwannoma after endoscopic excision; this patient also had a large extratracheal component, as in our case. Although extraluminal infiltration was suspected in our patient pre-operatively, we did not suspect attachment of the tumour to the oesophagus.
• Ancient schwannoma is a rare variant of schwannoma and is usually located deep in the head and neck region
• The degenerative changes occurring in this tumour are the result of long-term progression
• A case of ancient schwannoma of the oesophagus is reported, with a rare presentation and requiring tracheal resection for management
Conclusions
Treatment options for oesophageal schwannoma are dependent on the nature of the lesion and the involvement of adjacent structures. Our experience emphasises that the possibility of an oesophageal schwannoma should always be kept in mind when dealing with posterior tracheal tumours, and that laser therapy for similar lesions should be used judiciously. Prior, meticulous surgical planning is the key to avoiding potential complications.
