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Schwannoma of the Oral Cavity
Yamashita, Toida, Hatakeyama, et al
Asian J Oral Maxillofac Surg 2006;18(1):75-78. CASE REPORT
Schwannoma of the Oral Cavity Tomomi Yamashita, Makoto Toida, Daijiro Hatakeyama, Kazuhiro Yonemoto, Yukihiro Kusunoki, Toshiyuki Shibata Department of Oral and Maxillofacial Sciences, Graduate School of Medicine, Gifu University, Gifu, Japan
Abstract Intraoral occurrence of schwannoma is relatively rare. This report is of 4 patients with schwannoma of the oral cavity. The presenting complaint for all patients was intraoral submucosal swelling. The tumour arose in the tongue in 2 patients, the retromolar region in 1, and the buccal mucosa in 1. One of the tumours originating in the tongue was located in an unusual site, beneath the hyoglossal muscle layer. All 4 patients underwent surgery for tumour excision and the tumours were then diagnosed as schwannomas. Histologically, Antoni A tissue was observed in all tumours and was the predominant feature in 3 tumours; Antoni B tissue associated with cystic degeneration and necrosis was also identified in 1 tumour. Key words: Magnetic resonance imaging, Nerve sheath neoplasms
Introduction Schwannoma is a benign encapsulated nerve sheath tumour that is composed of Schwann cells. The lesion involves the peripheral nerves, including the cranial nerves (except for the optic and olfactory nerves), spinal nerves, and autonomic nerves where neurones and their axons are encased by Schwann cells.1 There is no predilection for either sex. 2 Intraoral occurrence of schwannoma is relatively rare,3-5 with approximately half of the intraoral schwannomas occurring in the tongue.6,7 This report is of 4 patients with schwannoma of the oral cavity treated at the Department of Oral and Maxillofacial Surgery, Gifu University Hospital, Gifu, Japan, from 1991 to 2004.
Case Reports Patient 1 A 61-year-old woman presented in 1991 with a lesion of the buccal mucosa, which she had first noted 11 months previously. Clinical examination revealed a 2.5-cm non-tender non-ulcerated globular mass below the buccal mucosa of the left cheek. Ultrasound investigation showed that the edge of the Correspondence: Tomomi Yamashita, 1-1 Yanagido, Gifu, Gifu, Japan. Tel: (81 58) 230 6355; Fax: (81 58) 230 6356; E-mail: [email protected]
© Asian 2006J Asian Oral Maxillofac Association Surg of Oral Vol 18, andNo Maxillofacial 1, 2006 Surgeons.
mass was clear and the internal echo was uniformly low. Magnetic resonance imaging (MRI) revealed a well-circumscribed solid mass. The lesion was homogenous and uniformly isointense to the surrounding muscle tissues on T1-weighted images, and hyperintense on T2-weighted images. The preoperative diagnosis was a benign tumour. The well-encapsulated mass was removed under general anaesthesia, and diagnosed histopathologically as an Antoni A type schwannoma. An associated nerve was not identified during the operation. The postoperative course was uneventful and there have been no signs of recurrence after 13 years of follow up. Patient 2 A 31-year-old woman presented in 1995 with a painless mass of the tongue of approximately 5 years duration. Intraoral examination revealed a 0.5-cm firm movable lesion, with a broad pedicle attached to the dorsal surface of the anterior third of the right tongue, covered by normal mucosa. The differential diagnosis included an irritation fibroma. The lesion was removed under local anaesthesia. Histologically, the lesion was diagnosed as an Antoni A type schwannoma. An associated nerve was not identified during the operation. The postoperative course was uneventful and there have been no signs of recurrence after 9 years of follow-up. 75
Schwannoma of the Oral Cavity
Patient 3 A 63-year-old woman presented in 2000 with a painless mass in the retromolar area of 10 months duration. Intraoral examination revealed a 1-cm tender non-ulcerated globular mass under the retromolar mucosa. Orthopantomography revealed a well-circumscribed defect of the left retromolar mandible under the mass. The preoperative diagnosis was benign tumour. The lesion was removed under local anaesthesia. Histologically, the tumour was an Antoni A type schwannoma. An associated nerve was not identified during the operation. The postoperative course was uneventful and there have been no signs of recurrence after 4 years of follow up.
The lesion was homogenous and uniformly isointense to the surrounding muscle tissues with ring enhancement using contrast medium on T1weighted images (Figure 2a). On T2-weighted images, marginal hyperintense and internal hypointense images were seen (Figure 2b). MRI findings suggested haemangioma with internal organisation. Fine-needle aspiration biopsy (FNAB) revealed only that the lesion was not malignant. The preoperative diagnosis was benign tumour or cyst. The encapsulated mass was removed under general a
Patient 4 A 61-year-old woman presented in 2003 with a mass on the tongue. She had first noted the mass 36 months earlier, but the mass gradually enlarged and became painful 4 days before presentation. At first examination, pus was observed to be discharging from the covering mucosa. After antibiotic therapy, clinical examination revealed a 3.5-cm non-tender globular mass under the left ventral surface of the tongue (Figure 1). At investigation, the edge of the mass was almost clear and the internal echo was not uniform. MRI revealed a well-circumscribed mass.
b
Figure 1. Lesion on the left side of the tongue with normal overlying mucosa.
76
Figure 2. Magnetic responance imaging showing (a) a wellcircumscribed homogenous mass that is uniformly isointense with the surrounding muscle tissues (coronal T1-weighted); and (b) marginal hyperintense and internal hypointense appearance (coronal T2-weighted). Asian J Oral Maxillofac Surg Vol 18, No 1, 2006
Yamashita, Toida, Hatakeyama, et al
Figure 3. Granulation tissue with infiltration of lymphocytes, haemorrhage, necrosis, and cystic change seen in the tumour (haematoxylin and eosin; original magnification, x 40).
Figure 4. Antoni A pattern with Verocay bodies and Antoni B pattern with myxoid stroma (haematoxylin and eosin; original magnification, x 200).
anaesthesia. The tumour was located beneath the hyoglossus muscle layer and an associated nerve was not identified during the operation. Histologically, a schwannoma was identified, mainly consisting of Antoni A areas, but Antoni B areas were also seen (Figures 3 and 4). In the Antoni B areas, cystic degeneration and necrosis were observed. The postoperative course was uneventful and there have been no signs of reccurence 14 months after surgery.
Incisional or FNAB may improve the accuracy of the preoperative diagnosis. Excision is not necessarily indicated if the tumour is small or located deep in the tissues, and the accuracy of the diagnosis by cytological biopsy is not in doubt.9 For patient 4, the preoperative diagnosis was very difficult despite investigation because the tumour was located deep in the tongue and its features were modified by infection.
Discussion Schwannomas of the oral cavity are rare. The differential diagnosis includes epidermoid and dermoid cysts, granular cell myoblastoma, haemangioma, leiomyoma, lingual thyroid, rhabdomyoma, and salivary gland tumours. There are other tumours that occur in the oral cavity from which schwannomas have to be diagnostically distinguished. However, schwannomas are difficult to recognise because they have few clinical characteristics. They are usually diagnosed accurately after removal of the lesion as a benign tumour. MRI has increased the possibility of establishing a correct preoperative diagnosis. On MRI, schwannomas appear as a welldemarcated isointense lesion to the surrounding muscle tissues on T1-weighted images.8 On T2weighted images, the lesion appears to be nonuniform hypointense in the Antoni A areas and nonuniform hyperintense in the Antoni B areas.7 Asian J Oral Maxillofac Surg Vol 18, No 1, 2006
As schwannomas grow larger, they tend to outgrow the blood supply and may undergo cystic degeneration in some areas.9 Also, in the patients described in this report, tumours less than 3 cm in diameter were Antoni A type and the larger tumour showed both Antoni A and Antoni B areas associated with cystic degeneration and necrosis. It is possible that the Antoni type does not represent a difference in the character of schwannomas, but it possibly has an association with its growth, although this is not demonstrable among these patients. Furthermore, recurrence and malignant change of schwannomas are uncommon,10 although some malignant transformations have been reported. Therefore, clinical follow-up is important.
References 1. Shimura K, Allen EC, Kinoshita Y, Takaesu T. Central neurilemoma of the mandible: report of case and review of the literature. J Oral Surg 1973;31:363-367. 77
Schwannoma of the Oral Cavity
2. Weiss SW, Goldblum JR, editors. Enzinger and Weiss’s soft tissue tumors. 4th ed. St Louis: Mosby-Year Book; 2001. 3. Das Gupta TK, Brasfield RD, Strong EW, Hajdu SI. Benign solitary schwannomas (neurilemomas). Cancer 1969;24: 355-366. 4. Leu YS, Chang KC. Extracranial head and neck schwannomas: a review of 8 years experience. Acta Otolaryngol 2002;122:435-437. 5. Pfeifle R, Baur DA, Paulino A, Helman J. Schwannoma of the tongue: report of 2 cases. J Oral Maxillofac Surg 2001; 59:802-804. 6. Wright BA, Jackson D. Neural tumors of the oral cavity: a review of the spectrum of benign and malignant oral tumors of the oral cavity and jaws. Oral Surg Oral Med Oral Pathol
78
1980;49:509-522. 7. Gallo WJ, Moss M, Shapiro DN, Gaul JV. Neurilemmoma: review of the literature and report of five cases. J Oral Surg 1977;35:235-236. 8. Flickinger FW, Lozano RL, Yuh WTC, Sachs MA. Neurilemoma of the tongue: MR findings. J Comput Assist Tomogr 1989;13:886-888. 9. Zhao K, Qi DY, Zhang KH. A comparison between the clinical behavior of neurilemmomas in the neck and oral and maxillofacial region. J Oral Maxillofac Surg 1993;51: 769-771. 10. Firfer H, Sohn D, Heurlin R, Stuteville OH. Neurilemmoma of the tongue. Oral Surg Oral Med Oral Pathol 1966;21: 139-142.
Asian J Oral Maxillofac Surg Vol 18, No 1, 2006
Asian J Oral Maxillofac Surg 2006;18(1):75-78. CASE REPORT
Schwannoma of the Oral Cavity Tomomi Yamashita, Makoto Toida, Daijiro Hatakeyama, Kazuhiro Yonemoto, Yukihiro Kusunoki, Toshiyuki Shibata Department of Oral and Maxillofacial Sciences, Graduate School of Medicine, Gifu University, Gifu, Japan
Abstract Intraoral occurrence of schwannoma is relatively rare. This report is of 4 patients with schwannoma of the oral cavity. The presenting complaint for all patients was intraoral submucosal swelling. The tumour arose in the tongue in 2 patients, the retromolar region in 1, and the buccal mucosa in 1. One of the tumours originating in the tongue was located in an unusual site, beneath the hyoglossal muscle layer. All 4 patients underwent surgery for tumour excision and the tumours were then diagnosed as schwannomas. Histologically, Antoni A tissue was observed in all tumours and was the predominant feature in 3 tumours; Antoni B tissue associated with cystic degeneration and necrosis was also identified in 1 tumour. Key words: Magnetic resonance imaging, Nerve sheath neoplasms
Introduction Schwannoma is a benign encapsulated nerve sheath tumour that is composed of Schwann cells. The lesion involves the peripheral nerves, including the cranial nerves (except for the optic and olfactory nerves), spinal nerves, and autonomic nerves where neurones and their axons are encased by Schwann cells.1 There is no predilection for either sex. 2 Intraoral occurrence of schwannoma is relatively rare,3-5 with approximately half of the intraoral schwannomas occurring in the tongue.6,7 This report is of 4 patients with schwannoma of the oral cavity treated at the Department of Oral and Maxillofacial Surgery, Gifu University Hospital, Gifu, Japan, from 1991 to 2004.
Case Reports Patient 1 A 61-year-old woman presented in 1991 with a lesion of the buccal mucosa, which she had first noted 11 months previously. Clinical examination revealed a 2.5-cm non-tender non-ulcerated globular mass below the buccal mucosa of the left cheek. Ultrasound investigation showed that the edge of the Correspondence: Tomomi Yamashita, 1-1 Yanagido, Gifu, Gifu, Japan. Tel: (81 58) 230 6355; Fax: (81 58) 230 6356; E-mail: [email protected]
© Asian 2006J Asian Oral Maxillofac Association Surg of Oral Vol 18, andNo Maxillofacial 1, 2006 Surgeons.
mass was clear and the internal echo was uniformly low. Magnetic resonance imaging (MRI) revealed a well-circumscribed solid mass. The lesion was homogenous and uniformly isointense to the surrounding muscle tissues on T1-weighted images, and hyperintense on T2-weighted images. The preoperative diagnosis was a benign tumour. The well-encapsulated mass was removed under general anaesthesia, and diagnosed histopathologically as an Antoni A type schwannoma. An associated nerve was not identified during the operation. The postoperative course was uneventful and there have been no signs of recurrence after 13 years of follow up. Patient 2 A 31-year-old woman presented in 1995 with a painless mass of the tongue of approximately 5 years duration. Intraoral examination revealed a 0.5-cm firm movable lesion, with a broad pedicle attached to the dorsal surface of the anterior third of the right tongue, covered by normal mucosa. The differential diagnosis included an irritation fibroma. The lesion was removed under local anaesthesia. Histologically, the lesion was diagnosed as an Antoni A type schwannoma. An associated nerve was not identified during the operation. The postoperative course was uneventful and there have been no signs of recurrence after 9 years of follow-up. 75
Schwannoma of the Oral Cavity
Patient 3 A 63-year-old woman presented in 2000 with a painless mass in the retromolar area of 10 months duration. Intraoral examination revealed a 1-cm tender non-ulcerated globular mass under the retromolar mucosa. Orthopantomography revealed a well-circumscribed defect of the left retromolar mandible under the mass. The preoperative diagnosis was benign tumour. The lesion was removed under local anaesthesia. Histologically, the tumour was an Antoni A type schwannoma. An associated nerve was not identified during the operation. The postoperative course was uneventful and there have been no signs of recurrence after 4 years of follow up.
The lesion was homogenous and uniformly isointense to the surrounding muscle tissues with ring enhancement using contrast medium on T1weighted images (Figure 2a). On T2-weighted images, marginal hyperintense and internal hypointense images were seen (Figure 2b). MRI findings suggested haemangioma with internal organisation. Fine-needle aspiration biopsy (FNAB) revealed only that the lesion was not malignant. The preoperative diagnosis was benign tumour or cyst. The encapsulated mass was removed under general a
Patient 4 A 61-year-old woman presented in 2003 with a mass on the tongue. She had first noted the mass 36 months earlier, but the mass gradually enlarged and became painful 4 days before presentation. At first examination, pus was observed to be discharging from the covering mucosa. After antibiotic therapy, clinical examination revealed a 3.5-cm non-tender globular mass under the left ventral surface of the tongue (Figure 1). At investigation, the edge of the mass was almost clear and the internal echo was not uniform. MRI revealed a well-circumscribed mass.
b
Figure 1. Lesion on the left side of the tongue with normal overlying mucosa.
76
Figure 2. Magnetic responance imaging showing (a) a wellcircumscribed homogenous mass that is uniformly isointense with the surrounding muscle tissues (coronal T1-weighted); and (b) marginal hyperintense and internal hypointense appearance (coronal T2-weighted). Asian J Oral Maxillofac Surg Vol 18, No 1, 2006
Yamashita, Toida, Hatakeyama, et al
Figure 3. Granulation tissue with infiltration of lymphocytes, haemorrhage, necrosis, and cystic change seen in the tumour (haematoxylin and eosin; original magnification, x 40).
Figure 4. Antoni A pattern with Verocay bodies and Antoni B pattern with myxoid stroma (haematoxylin and eosin; original magnification, x 200).
anaesthesia. The tumour was located beneath the hyoglossus muscle layer and an associated nerve was not identified during the operation. Histologically, a schwannoma was identified, mainly consisting of Antoni A areas, but Antoni B areas were also seen (Figures 3 and 4). In the Antoni B areas, cystic degeneration and necrosis were observed. The postoperative course was uneventful and there have been no signs of reccurence 14 months after surgery.
Incisional or FNAB may improve the accuracy of the preoperative diagnosis. Excision is not necessarily indicated if the tumour is small or located deep in the tissues, and the accuracy of the diagnosis by cytological biopsy is not in doubt.9 For patient 4, the preoperative diagnosis was very difficult despite investigation because the tumour was located deep in the tongue and its features were modified by infection.
Discussion Schwannomas of the oral cavity are rare. The differential diagnosis includes epidermoid and dermoid cysts, granular cell myoblastoma, haemangioma, leiomyoma, lingual thyroid, rhabdomyoma, and salivary gland tumours. There are other tumours that occur in the oral cavity from which schwannomas have to be diagnostically distinguished. However, schwannomas are difficult to recognise because they have few clinical characteristics. They are usually diagnosed accurately after removal of the lesion as a benign tumour. MRI has increased the possibility of establishing a correct preoperative diagnosis. On MRI, schwannomas appear as a welldemarcated isointense lesion to the surrounding muscle tissues on T1-weighted images.8 On T2weighted images, the lesion appears to be nonuniform hypointense in the Antoni A areas and nonuniform hyperintense in the Antoni B areas.7 Asian J Oral Maxillofac Surg Vol 18, No 1, 2006
As schwannomas grow larger, they tend to outgrow the blood supply and may undergo cystic degeneration in some areas.9 Also, in the patients described in this report, tumours less than 3 cm in diameter were Antoni A type and the larger tumour showed both Antoni A and Antoni B areas associated with cystic degeneration and necrosis. It is possible that the Antoni type does not represent a difference in the character of schwannomas, but it possibly has an association with its growth, although this is not demonstrable among these patients. Furthermore, recurrence and malignant change of schwannomas are uncommon,10 although some malignant transformations have been reported. Therefore, clinical follow-up is important.
References 1. Shimura K, Allen EC, Kinoshita Y, Takaesu T. Central neurilemoma of the mandible: report of case and review of the literature. J Oral Surg 1973;31:363-367. 77
Schwannoma of the Oral Cavity
2. Weiss SW, Goldblum JR, editors. Enzinger and Weiss’s soft tissue tumors. 4th ed. St Louis: Mosby-Year Book; 2001. 3. Das Gupta TK, Brasfield RD, Strong EW, Hajdu SI. Benign solitary schwannomas (neurilemomas). Cancer 1969;24: 355-366. 4. Leu YS, Chang KC. Extracranial head and neck schwannomas: a review of 8 years experience. Acta Otolaryngol 2002;122:435-437. 5. Pfeifle R, Baur DA, Paulino A, Helman J. Schwannoma of the tongue: report of 2 cases. J Oral Maxillofac Surg 2001; 59:802-804. 6. Wright BA, Jackson D. Neural tumors of the oral cavity: a review of the spectrum of benign and malignant oral tumors of the oral cavity and jaws. Oral Surg Oral Med Oral Pathol
78
1980;49:509-522. 7. Gallo WJ, Moss M, Shapiro DN, Gaul JV. Neurilemmoma: review of the literature and report of five cases. J Oral Surg 1977;35:235-236. 8. Flickinger FW, Lozano RL, Yuh WTC, Sachs MA. Neurilemoma of the tongue: MR findings. J Comput Assist Tomogr 1989;13:886-888. 9. Zhao K, Qi DY, Zhang KH. A comparison between the clinical behavior of neurilemmomas in the neck and oral and maxillofacial region. J Oral Maxillofac Surg 1993;51: 769-771. 10. Firfer H, Sohn D, Heurlin R, Stuteville OH. Neurilemmoma of the tongue. Oral Surg Oral Med Oral Pathol 1966;21: 139-142.
Asian J Oral Maxillofac Surg Vol 18, No 1, 2006