- Email: [email protected]
Solitary Fibrous Tumour of the Buccal Mucosa: Immunohistochemical and Ultrastructural Observation
Mizuno, et al Asian J OralTanamoto, MaxillofacKawasaki, Surg 2003;15:199-204.
Asian J Oral Maxillofac Surg 2003;15:1xx-1xx. CASE REPORTS
Solitary Fibrous Tumour of the Buccal Mucosa: Immunohistochemical and Ultrastructural Observation Souichi Yanamoto,1 Goro Kawasaki,1 Akio Mizuno,1 Shuichi Fujita2 Division of Oral and Maxillofacial Surgery and 2Division of Oral Pathology and Bone Metabolism, Department of Developmental and Reconstructive Medicine, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan 1
Abstract Solitary fibrous tumour is a benign soft tissue tumour, most often localised in the pleura but recently described in other body sites. However, solitary fibrous tumour in the oral cavity is distinctly uncommon. A patient with this tumour in the oral cavity is described in this report. Magnetic resonance angiography revealed that the tumour was suspected to be a haemangioma. The tumour was surgically removed and was found to 3.5 x 2.8 x 2.5 cm in size. Histologically, the tumour was comprised of numerous ovoid- or spindle-shaped cells and many blood vessels with haemangiopericytoma-like appearance. The tumour cells immunoreacted for vimentin, CD34, and bcl-2. Ultrastructurally, a small amount of collagen fibrils were associated with the neoplastic cells, and cytoplasmic organelles were not developed. The tumour was considered to be predominantly composed of immature fibroblasts. The patient has had no recurrence. Key words: Buccal mucosa, Immunohistochemistry, Tumor, Ultrastructure
Introduction
Case Report
Solitary fibrous tumour (SFT) was initially described in the pleura by Klemperer and Rabin.1 SFT was once termed localised fibrous mesothelioma because of its mesothelial origin.2 SFTs are generally difficult to diagnose because of their broad range of morphologic characteristics.
A 32-year-old man was referred to the Division of Oral and Maxillofacial Surgery at Nagasaki University Graduate School of Biomedical Sciences, Japan, because of an asymptomatic submucosal mass involving the right buccal mucosa. He had noticed this 1 year earlier, and mentioned that the lesion was painless and that there was no increase in size.
Although SFTs had commonly been considered to arise in the pleura,2,3 recent reports indicate that these tumours may originate from extrapleural and extraperitoneal sites, including the nasal cavity,4 orbit,5 breast,6 thyroid,7 renal pelvis,8 pharynx,9 parotid gland,10 and submandibular gland.11 However, SFT in the oral cavity is distinctly uncommon, with only 30 previous cases reported in the English literature.11-20 A patient with SFT occurring in the buccal mucosa is reported in this article. Correspondence: Souichi Yanamoto, Division of Oral and Maxillofacial Surgery, Department of Developmental and Reconstructive Medicine, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan. Tel: (81 95) 849 7698; Fax: (81 95) 849 7700 E-mail: [email protected]
Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Facial examination showed an elastic soft, nontender mobile mass that was approximately 4 cm in diameter and could be palpated intraorally and extraorally lateral to the philtrum. Intraoral examination revealed that the colour and texture of the overlying buccal mucosa was normal (Figure 1). At magnetic resonance imaging (MRI), the mass showed low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and heterogeneous enhancement on Gadolium-enhanced MRI (Figure 2). Coronal magnetic resonance angiography (MRA) showed high heterogeneous and surrounding enhanced lesion (Figure 3). The lesion was adjacent to the right maxillary and facial arteries. The lesion 199
Solitary Fibrous Tumour of the Buccal Mucosa
Figure 1. Intraoral findings reveal an elastic soft and nontender mobile mass of the buccal mucosa.
Figure 4. The surface of the divided mass is solid and elastic hard with greyish-white tissue.
Figure 2. Axial gadolinium-enhanced T1-weighted magnetic resonance imaging shows heterogenous enhancement.
Figure 5. Densely cellular and collagen rich areas are mixed in the tumour. Irregularly dilated blood vessels reveal stag-horn appearance. (Hematoxylin and eosin stain, magnification x 90).
Figure 3. Coronal magnetic resonance angiography shows high heterogenous and surround enhanced lesion.
was clinically diagnosed as a haemangioma. Surgical excision was performed under general anaesthesia. As the tumour surface was smooth and clearly defined, it could be easily dissected from the surrounding tissue. 200
The mass measured 3.5 x 2.8 x 2.5 cm and was well demarcated. Cut surface showed solid and greyish-white tissue (Figure 4). Histologically, the circumscribed specimen was composed of ovoidor spindle-shaped fibroblast-like cells with various amounts of collagen bundles haphazardly arranged. Hypercellular, hypocellular, and myxoid areas were mixed within the tumour. Many intermingled blood vessels revealed irregular dilatation with stag-horn appearance that is occasionally seen in haemangiopericytoma. There was no nuclear atypism and mitotic figures were hardly seen (Figures 5 and 6). Immunohistochemical examination demonstrated that the Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Tanamoto, Kawasaki, Mizuno, et al
Figure 6. Ovoid- or spindle-shaped cells proliferate accompanied with blood capillaries containing erythrocytes. Nuclear atypia is rare. (Hematoxylin and eosin stain, magnification x 350).
Figure 7. Most neoplastic cells and endothelial cells demonstrate immunoreaction with CD34. (Immunohistochemical stain, magnification x 350).
neoplastic cells were positive for vimentin, CD34 (Figure 7), and bcl-2 (Figure 8), but negative for cytokeratin, von Willebrand factor (factor VIIIrelated antigen), smooth muscle actin, and S-100 protein. Ultrastructurally, neoplastic cells individually proliferated or clustered in the cellular area. Blood capillaries were intermingled in the tumour (Figure Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Figure 8. Neoplastic cells are immunohistochemically-positive for bcl-2, while endothelial cells exhibit no reaction (arrow heads). (Immunohistochemical stain, magnification x 350).
Figure 9. Tumour cells have large nuclei. Extracellular matrix is not abundant. Blood capillaries (asterisks) neighbour the neoplastic cells. (Magnification x 2800).
9). Oval nuclei included round large nucleoli. In the cytoplasm, cytoplasmic organelles were not developed. Sparse rough endoplasmic reticulum and mitochondria were noticed. Basement membrane around the tumour cells and clusters was not distinct except for around the endothelial cells of blood capillaries. The tumour cells were associated with rare bundles of collagen fibrils in intercellular spaces (Figure 10). These findings suggested that the 201
Solitary Fibrous Tumour of the Buccal Mucosa
enhancement on Gadolinium-enhanced MRI. There have been very few reports of an MRI appearance of SFT.10,16,21 Sato et al reported that the low signal intensity on both T1 and T2-weighted images would be characteristic of SFT.10 However, for this patient, the T2-weighted image showed high signal intensity. In addition to these MRI findings, coronal MRA showed the mass as a heterogeneous and surrounding enhanced lesion. These findings of MRI and MRA were compared with those of the pathological examination for this patient — it was suggested that T2-weighted MRI and MRA showed a haemangioma-type appearance because of the many blood vessels with haemangiopericytoma-like appearance. Figure 10. Sparse rough endoplasmic reticulum and mitochondria are seen in the cytoplasm. Small amount of collagen fibrils are noticed in the intercellular spaces (asterisk). Basement membrane is not prominent except for around the endothelial cells (arrow heads). (Magnification x 5800).
neoplastic cells were immature fibroblasts. The pathological examination indicated that the tumour was SFT.
Discussion Although SFTs are generally difficult to diagnose because of their broad range of morphologic characteristics, the diagnosis is usually based on microscopic appearance with immunohistochemical studies.3,18 The differential diagnosis of oral SFT includes various tumours such as haemangiopericytoma, nerve sheath tumour, and dermatofibrosarcoma protuberans.3,18 In 1997, Chan proposed the diagnostic criteria of several essential diagnostic features for SFT.3 This author also proposed the immunohistochemical profile, namely that SFT is immunopositive for vimentin, CD34, and bcl-2, but is negative for cytokeratin, von Willebrand factor, smooth muscle actin, and S-100 protein. The pathological findings in this patient were consistent with all of the histological criteria of SFT proposed by Chan. 3 Furthermore, the immunohistochemical findings also fitted the diagnostic profile. Therefore, the lesion was diagnosed as SFT. At MRI, the findings for this patient revealed low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and heterogeneous 202
Oral SFT is a rare tumour. There have only been 30 patients reported in the English literature.11-20 Although Alawi et al described the largest single report of 16 patients, 10 were reclassified as SFT by a retrospective study.18 Some authors have suggested that some patients with SFT were misdiagnosed as other soft tissue tumours before the immunohistochemical localisation of CD34 in SFT was identified.3,16,18 Indeed, since Renshaw et al reported the relationship between CD34 immunopositivity and SFT in 1994,22 publications on the occurrence of SFT in extrapleural and extraperitoneal sites have increased throughout the world. Although the histogenesis of SFT remains controversial, recent studies suggest that the immunopositivity for CD34 is associated with the mesenchymal origin of SFT.3,8,22 Therefore, SFT is thought to arise from either fibroblastic or myofibroblastic lineage, because CD34 is a fibroblast-associated antigen. Also, Krismann et al reported that a single loss on chromosome 13q was detected by comparative genomic hybridisation, and suggested that a tumour suppressor gene mapped at 13q was associated with the molecular pathogenesis of SFT.21 On the other hand, Lukinmaa et al reported a history of trauma in the affected area before the onset of the lesion, and suggested a possible role for trauma in the aetiology and development of oral SFT. 17 However, such gene analysis could not be performed for this patient and he had no history of injury. Therefore, the pathogenesis for this patient remains unknown. Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Tanamoto, Kawasaki, Mizuno, et al
Since most SFTs are clinically benign tumours, the recommended management is complete surgical resection. Although oral SFTs have generally been benign, some reports have indicated that 5% to 20% of pleural SFTs have recurrence and histological malignancy.2,3 In addition, Chan suggested that atypical histological findings would be a predictive factor of aggressive behaviour.3 Atypical histological findings include a lack of circumscription, nuclear atypia, hypercellularity, and a mitotic count of ≥4 per 10 high power fields and necrosis. In this patient, nuclear atypia and an increased number of mitotic figures were not detected, although densely cellular areas were partially demonstrated. Nielsen et al studied 15 patients with SFT using microscopic, immunohistochemical, and ultrastructural techniques.23 These authors suggested that most neoplastic SFT cells differentiated into fibroblastic or myofibroblastic cells except for 1 patient with less fibroblastic differentiation. In our patient, ultrastructural examination showed that the tumour cells had poor cytoplasmic organelles. This tumour might therefore be comprised of numerous immature fibroblasts rather than differentiated fibroblasts, so it was considered that long-term follow-up was very important.
References 1. Klemperer P, Rabin C. Primary neoplasms of the pleura. Arch Pathol 1931;11:385-412. 2. England DM, Hochholzer L, McCarthy MJ. Localized benign and malignant fibrous tumors of the pleura: a clinicopathologic review of 223 cases. Am J Surg Pathol 1989;13:640-658. 3. Chan JKC. Solitary fibrous tumor-everywhere, and a diagnosis in vogue. Histopathology 1997; 31:568-576. 4. Zukerberg LR, Rosenberg AE, Randolph G, Pilch BZ, Goodman ML. Solitary fibrous tumor of the nasal cavity and paranasal sinuses. Am J Surg Pathol 1991;15:126-130. 5. Weatra WH, Gerald WL, Rosai J. Solitary fibrous tumor: consistent CD34 immunoreactivity and occurrence in the orbit. Am J Surg Pathol 1994;18: 992-998. 6. Damiani S, Miettinen M, Peterse JL, Eusebi V. Solitary fibrous tumor of the breast. Virchows Arch 1994;425:89-92. Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
7. Cameselle-Teijeiro J, Varela-Duran J, Fonseca E, Villanueva JP, Sobrinho-Simoes M. Solitary fibrous tumor of the thyroid. Am J Clin Pathol 1994;101:535-538. 8. Fukunaga M, Nikaido T. Solitary fibrous tumor of the renal peripelvis. Histopathology 1997;30: 451-456. 9. Al-Sinawi A, Johns AN. Parapharyngeal solitary fibrous tumor: an incidental finding at ENT examination. J Laryngol Otol 1994;108:344-347. 10. Sato J, Asakura K, Yokoyama Y, Satoh M. Solitary fibrous tumor of the parotid gland extending to the parapharyngeal space. Eur Arch Otorhinolaryngol 1998;255:18-21. 11. Gunhan O, Yildiz FR, Celasun B, Onder T, Finci R. Solitary fibrous tumor arising from sublingual gland: report of a case. J Laryngol Otol 1994; 108:998-1000. 12. Suster S, Nascimento AG, Miettinen M, Sickel JZ, Moran CA. Solitary fibrous tumors of soft tissue: a clinicopathologic and immunohistochemical study of 12 cases. Am J Surg Pathol 1995;19:1257-1266. 13. Piattelli A, Fioroni M, Rubini C. Solitary fibrous tumor of the tongue. Oral Oncol 1998;34: 431-434. 14. Kurihara K, Mizuseki K, Sonobe J, Yanagihara J. Solitary fibrous tumor of the oral cavity: report of a case. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:223-226. 15. Perez-Ordonez B, Koutlas IG, Strich E, Gilbert RW, Jordan RCK. Solitary fibrous tumor of the oral cavity: an uncommon location for a ubiquitous neoplasm. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:589-593. 16. Iwai S, Nakazawa M, Yoshikawa F, Amekawa S, Sakuda M. Solitary fibrous tumor of the buccal mucosa: report of a case with immunohistochemical studies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88:461-465. 17. Lukinmaa PL, Hietanen J, Warfvinge G, Sane J, Tuominen S, Henriksson V, Larsson A. Solitary fibrous tumor of the oral cavity: clinicopathologic and immunohistochemical characterization of three cases. J Oral Pathol Med 2000;29:186-192. 18. Alawi F, Stratton D, Freedman PD. Solitary fibrous tumor of the oral soft tissues: a clinicopathologic and immunohistochemical study of 16 203
Solitary Fibrous Tumour of the Buccal Mucosa
cases. Am J Surg Pathol 2001;25:900-910. 19. Kuo WP, Sirois DA, Pemble CW. Locally aggressive solitary fibrous tumor in the infraorbital region: A case report and review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:308-311. 20. Hirano M, Tanuma J, Shimoda T, Sugihara K, Tsuneyoshi M, Kitano M. Solitary fibrous tumor in the mental region. Pathol Int 2001;51:905-908. 21. Krismann M, Adams H, Jaworska M, Muller KM, Johnen G. Benign solitary fibrous tumor of the thigh: morphological, chromosomal and
204
differential diagnostic aspects. Langenbeck’s Arch Surg 2000;385:521-525. 22. Renshaw AA, Paulus W, Joseph JT. CD34 and epithelial membrane antigen distinguish dural hemangiopericytoma and meningioma. Applied Immunohistochemistry 1995;3:108-114. 23. Nielsen GP, O’Connell JX, Dickersin GR, Rosenberg AE. Solitary fibrous tumor of soft tissue: A report of 15 cases, including 5 malignant examples with light microscopic, immunohistochemical, and ultrastructural data. Mod Pathol 1997;10:1028-1037.
Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Asian J Oral Maxillofac Surg 2003;15:1xx-1xx. CASE REPORTS
Solitary Fibrous Tumour of the Buccal Mucosa: Immunohistochemical and Ultrastructural Observation Souichi Yanamoto,1 Goro Kawasaki,1 Akio Mizuno,1 Shuichi Fujita2 Division of Oral and Maxillofacial Surgery and 2Division of Oral Pathology and Bone Metabolism, Department of Developmental and Reconstructive Medicine, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan 1
Abstract Solitary fibrous tumour is a benign soft tissue tumour, most often localised in the pleura but recently described in other body sites. However, solitary fibrous tumour in the oral cavity is distinctly uncommon. A patient with this tumour in the oral cavity is described in this report. Magnetic resonance angiography revealed that the tumour was suspected to be a haemangioma. The tumour was surgically removed and was found to 3.5 x 2.8 x 2.5 cm in size. Histologically, the tumour was comprised of numerous ovoid- or spindle-shaped cells and many blood vessels with haemangiopericytoma-like appearance. The tumour cells immunoreacted for vimentin, CD34, and bcl-2. Ultrastructurally, a small amount of collagen fibrils were associated with the neoplastic cells, and cytoplasmic organelles were not developed. The tumour was considered to be predominantly composed of immature fibroblasts. The patient has had no recurrence. Key words: Buccal mucosa, Immunohistochemistry, Tumor, Ultrastructure
Introduction
Case Report
Solitary fibrous tumour (SFT) was initially described in the pleura by Klemperer and Rabin.1 SFT was once termed localised fibrous mesothelioma because of its mesothelial origin.2 SFTs are generally difficult to diagnose because of their broad range of morphologic characteristics.
A 32-year-old man was referred to the Division of Oral and Maxillofacial Surgery at Nagasaki University Graduate School of Biomedical Sciences, Japan, because of an asymptomatic submucosal mass involving the right buccal mucosa. He had noticed this 1 year earlier, and mentioned that the lesion was painless and that there was no increase in size.
Although SFTs had commonly been considered to arise in the pleura,2,3 recent reports indicate that these tumours may originate from extrapleural and extraperitoneal sites, including the nasal cavity,4 orbit,5 breast,6 thyroid,7 renal pelvis,8 pharynx,9 parotid gland,10 and submandibular gland.11 However, SFT in the oral cavity is distinctly uncommon, with only 30 previous cases reported in the English literature.11-20 A patient with SFT occurring in the buccal mucosa is reported in this article. Correspondence: Souichi Yanamoto, Division of Oral and Maxillofacial Surgery, Department of Developmental and Reconstructive Medicine, Course of Medical and Dental Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan. Tel: (81 95) 849 7698; Fax: (81 95) 849 7700 E-mail: [email protected]
Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Facial examination showed an elastic soft, nontender mobile mass that was approximately 4 cm in diameter and could be palpated intraorally and extraorally lateral to the philtrum. Intraoral examination revealed that the colour and texture of the overlying buccal mucosa was normal (Figure 1). At magnetic resonance imaging (MRI), the mass showed low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and heterogeneous enhancement on Gadolium-enhanced MRI (Figure 2). Coronal magnetic resonance angiography (MRA) showed high heterogeneous and surrounding enhanced lesion (Figure 3). The lesion was adjacent to the right maxillary and facial arteries. The lesion 199
Solitary Fibrous Tumour of the Buccal Mucosa
Figure 1. Intraoral findings reveal an elastic soft and nontender mobile mass of the buccal mucosa.
Figure 4. The surface of the divided mass is solid and elastic hard with greyish-white tissue.
Figure 2. Axial gadolinium-enhanced T1-weighted magnetic resonance imaging shows heterogenous enhancement.
Figure 5. Densely cellular and collagen rich areas are mixed in the tumour. Irregularly dilated blood vessels reveal stag-horn appearance. (Hematoxylin and eosin stain, magnification x 90).
Figure 3. Coronal magnetic resonance angiography shows high heterogenous and surround enhanced lesion.
was clinically diagnosed as a haemangioma. Surgical excision was performed under general anaesthesia. As the tumour surface was smooth and clearly defined, it could be easily dissected from the surrounding tissue. 200
The mass measured 3.5 x 2.8 x 2.5 cm and was well demarcated. Cut surface showed solid and greyish-white tissue (Figure 4). Histologically, the circumscribed specimen was composed of ovoidor spindle-shaped fibroblast-like cells with various amounts of collagen bundles haphazardly arranged. Hypercellular, hypocellular, and myxoid areas were mixed within the tumour. Many intermingled blood vessels revealed irregular dilatation with stag-horn appearance that is occasionally seen in haemangiopericytoma. There was no nuclear atypism and mitotic figures were hardly seen (Figures 5 and 6). Immunohistochemical examination demonstrated that the Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Tanamoto, Kawasaki, Mizuno, et al
Figure 6. Ovoid- or spindle-shaped cells proliferate accompanied with blood capillaries containing erythrocytes. Nuclear atypia is rare. (Hematoxylin and eosin stain, magnification x 350).
Figure 7. Most neoplastic cells and endothelial cells demonstrate immunoreaction with CD34. (Immunohistochemical stain, magnification x 350).
neoplastic cells were positive for vimentin, CD34 (Figure 7), and bcl-2 (Figure 8), but negative for cytokeratin, von Willebrand factor (factor VIIIrelated antigen), smooth muscle actin, and S-100 protein. Ultrastructurally, neoplastic cells individually proliferated or clustered in the cellular area. Blood capillaries were intermingled in the tumour (Figure Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Figure 8. Neoplastic cells are immunohistochemically-positive for bcl-2, while endothelial cells exhibit no reaction (arrow heads). (Immunohistochemical stain, magnification x 350).
Figure 9. Tumour cells have large nuclei. Extracellular matrix is not abundant. Blood capillaries (asterisks) neighbour the neoplastic cells. (Magnification x 2800).
9). Oval nuclei included round large nucleoli. In the cytoplasm, cytoplasmic organelles were not developed. Sparse rough endoplasmic reticulum and mitochondria were noticed. Basement membrane around the tumour cells and clusters was not distinct except for around the endothelial cells of blood capillaries. The tumour cells were associated with rare bundles of collagen fibrils in intercellular spaces (Figure 10). These findings suggested that the 201
Solitary Fibrous Tumour of the Buccal Mucosa
enhancement on Gadolinium-enhanced MRI. There have been very few reports of an MRI appearance of SFT.10,16,21 Sato et al reported that the low signal intensity on both T1 and T2-weighted images would be characteristic of SFT.10 However, for this patient, the T2-weighted image showed high signal intensity. In addition to these MRI findings, coronal MRA showed the mass as a heterogeneous and surrounding enhanced lesion. These findings of MRI and MRA were compared with those of the pathological examination for this patient — it was suggested that T2-weighted MRI and MRA showed a haemangioma-type appearance because of the many blood vessels with haemangiopericytoma-like appearance. Figure 10. Sparse rough endoplasmic reticulum and mitochondria are seen in the cytoplasm. Small amount of collagen fibrils are noticed in the intercellular spaces (asterisk). Basement membrane is not prominent except for around the endothelial cells (arrow heads). (Magnification x 5800).
neoplastic cells were immature fibroblasts. The pathological examination indicated that the tumour was SFT.
Discussion Although SFTs are generally difficult to diagnose because of their broad range of morphologic characteristics, the diagnosis is usually based on microscopic appearance with immunohistochemical studies.3,18 The differential diagnosis of oral SFT includes various tumours such as haemangiopericytoma, nerve sheath tumour, and dermatofibrosarcoma protuberans.3,18 In 1997, Chan proposed the diagnostic criteria of several essential diagnostic features for SFT.3 This author also proposed the immunohistochemical profile, namely that SFT is immunopositive for vimentin, CD34, and bcl-2, but is negative for cytokeratin, von Willebrand factor, smooth muscle actin, and S-100 protein. The pathological findings in this patient were consistent with all of the histological criteria of SFT proposed by Chan. 3 Furthermore, the immunohistochemical findings also fitted the diagnostic profile. Therefore, the lesion was diagnosed as SFT. At MRI, the findings for this patient revealed low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and heterogeneous 202
Oral SFT is a rare tumour. There have only been 30 patients reported in the English literature.11-20 Although Alawi et al described the largest single report of 16 patients, 10 were reclassified as SFT by a retrospective study.18 Some authors have suggested that some patients with SFT were misdiagnosed as other soft tissue tumours before the immunohistochemical localisation of CD34 in SFT was identified.3,16,18 Indeed, since Renshaw et al reported the relationship between CD34 immunopositivity and SFT in 1994,22 publications on the occurrence of SFT in extrapleural and extraperitoneal sites have increased throughout the world. Although the histogenesis of SFT remains controversial, recent studies suggest that the immunopositivity for CD34 is associated with the mesenchymal origin of SFT.3,8,22 Therefore, SFT is thought to arise from either fibroblastic or myofibroblastic lineage, because CD34 is a fibroblast-associated antigen. Also, Krismann et al reported that a single loss on chromosome 13q was detected by comparative genomic hybridisation, and suggested that a tumour suppressor gene mapped at 13q was associated with the molecular pathogenesis of SFT.21 On the other hand, Lukinmaa et al reported a history of trauma in the affected area before the onset of the lesion, and suggested a possible role for trauma in the aetiology and development of oral SFT. 17 However, such gene analysis could not be performed for this patient and he had no history of injury. Therefore, the pathogenesis for this patient remains unknown. Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
Tanamoto, Kawasaki, Mizuno, et al
Since most SFTs are clinically benign tumours, the recommended management is complete surgical resection. Although oral SFTs have generally been benign, some reports have indicated that 5% to 20% of pleural SFTs have recurrence and histological malignancy.2,3 In addition, Chan suggested that atypical histological findings would be a predictive factor of aggressive behaviour.3 Atypical histological findings include a lack of circumscription, nuclear atypia, hypercellularity, and a mitotic count of ≥4 per 10 high power fields and necrosis. In this patient, nuclear atypia and an increased number of mitotic figures were not detected, although densely cellular areas were partially demonstrated. Nielsen et al studied 15 patients with SFT using microscopic, immunohistochemical, and ultrastructural techniques.23 These authors suggested that most neoplastic SFT cells differentiated into fibroblastic or myofibroblastic cells except for 1 patient with less fibroblastic differentiation. In our patient, ultrastructural examination showed that the tumour cells had poor cytoplasmic organelles. This tumour might therefore be comprised of numerous immature fibroblasts rather than differentiated fibroblasts, so it was considered that long-term follow-up was very important.
References 1. Klemperer P, Rabin C. Primary neoplasms of the pleura. Arch Pathol 1931;11:385-412. 2. England DM, Hochholzer L, McCarthy MJ. Localized benign and malignant fibrous tumors of the pleura: a clinicopathologic review of 223 cases. Am J Surg Pathol 1989;13:640-658. 3. Chan JKC. Solitary fibrous tumor-everywhere, and a diagnosis in vogue. Histopathology 1997; 31:568-576. 4. Zukerberg LR, Rosenberg AE, Randolph G, Pilch BZ, Goodman ML. Solitary fibrous tumor of the nasal cavity and paranasal sinuses. Am J Surg Pathol 1991;15:126-130. 5. Weatra WH, Gerald WL, Rosai J. Solitary fibrous tumor: consistent CD34 immunoreactivity and occurrence in the orbit. Am J Surg Pathol 1994;18: 992-998. 6. Damiani S, Miettinen M, Peterse JL, Eusebi V. Solitary fibrous tumor of the breast. Virchows Arch 1994;425:89-92. Asian J Oral Maxillofac Surg Vol 15, No 3, 2003
7. Cameselle-Teijeiro J, Varela-Duran J, Fonseca E, Villanueva JP, Sobrinho-Simoes M. Solitary fibrous tumor of the thyroid. Am J Clin Pathol 1994;101:535-538. 8. Fukunaga M, Nikaido T. Solitary fibrous tumor of the renal peripelvis. Histopathology 1997;30: 451-456. 9. Al-Sinawi A, Johns AN. Parapharyngeal solitary fibrous tumor: an incidental finding at ENT examination. J Laryngol Otol 1994;108:344-347. 10. Sato J, Asakura K, Yokoyama Y, Satoh M. Solitary fibrous tumor of the parotid gland extending to the parapharyngeal space. Eur Arch Otorhinolaryngol 1998;255:18-21. 11. Gunhan O, Yildiz FR, Celasun B, Onder T, Finci R. Solitary fibrous tumor arising from sublingual gland: report of a case. J Laryngol Otol 1994; 108:998-1000. 12. Suster S, Nascimento AG, Miettinen M, Sickel JZ, Moran CA. Solitary fibrous tumors of soft tissue: a clinicopathologic and immunohistochemical study of 12 cases. Am J Surg Pathol 1995;19:1257-1266. 13. Piattelli A, Fioroni M, Rubini C. Solitary fibrous tumor of the tongue. Oral Oncol 1998;34: 431-434. 14. Kurihara K, Mizuseki K, Sonobe J, Yanagihara J. Solitary fibrous tumor of the oral cavity: report of a case. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:223-226. 15. Perez-Ordonez B, Koutlas IG, Strich E, Gilbert RW, Jordan RCK. Solitary fibrous tumor of the oral cavity: an uncommon location for a ubiquitous neoplasm. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;87:589-593. 16. Iwai S, Nakazawa M, Yoshikawa F, Amekawa S, Sakuda M. Solitary fibrous tumor of the buccal mucosa: report of a case with immunohistochemical studies. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88:461-465. 17. Lukinmaa PL, Hietanen J, Warfvinge G, Sane J, Tuominen S, Henriksson V, Larsson A. Solitary fibrous tumor of the oral cavity: clinicopathologic and immunohistochemical characterization of three cases. J Oral Pathol Med 2000;29:186-192. 18. Alawi F, Stratton D, Freedman PD. Solitary fibrous tumor of the oral soft tissues: a clinicopathologic and immunohistochemical study of 16 203
Solitary Fibrous Tumour of the Buccal Mucosa
cases. Am J Surg Pathol 2001;25:900-910. 19. Kuo WP, Sirois DA, Pemble CW. Locally aggressive solitary fibrous tumor in the infraorbital region: A case report and review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;92:308-311. 20. Hirano M, Tanuma J, Shimoda T, Sugihara K, Tsuneyoshi M, Kitano M. Solitary fibrous tumor in the mental region. Pathol Int 2001;51:905-908. 21. Krismann M, Adams H, Jaworska M, Muller KM, Johnen G. Benign solitary fibrous tumor of the thigh: morphological, chromosomal and
204
differential diagnostic aspects. Langenbeck’s Arch Surg 2000;385:521-525. 22. Renshaw AA, Paulus W, Joseph JT. CD34 and epithelial membrane antigen distinguish dural hemangiopericytoma and meningioma. Applied Immunohistochemistry 1995;3:108-114. 23. Nielsen GP, O’Connell JX, Dickersin GR, Rosenberg AE. Solitary fibrous tumor of soft tissue: A report of 15 cases, including 5 malignant examples with light microscopic, immunohistochemical, and ultrastructural data. Mod Pathol 1997;10:1028-1037.
Asian J Oral Maxillofac Surg Vol 15, No 3, 2003