CARTA AL DIRECTOR

Solitary fibrous tumor of the oral cavity with histologic characteristics of malignancy

Tumor fibroso solitario de la cavidad oral con características histológicas de malignidad

Dear Editor,

Recently, an interesting article about intraoral solitary fibrous tumor (SFT) was published in your journal (García de Marcos et al. Tumor fibroso solitario intraoral: clinicopatológico and inmunohistoquímico analysis. Rev Esp Cir Oral Maxilofac 2008;30:180-184). As the authors state correctly in their introduction, SFT is a rare soft tissue neoplasm formed by spindle cells that is found mainly on surfaces derived from the mesothelium. Despite being commonest in the parietal and visceral pleura, it has been reported in serosal and nonserosal locations, which supports the theory that neoplastic cells can originate from the dissemination of primitive cells.

Numerous SFT locations have been cited in the head and neck, such as skin, cervical deep soft tissues, thyroid, larynx, epiglottis, parapharyngeal space, major salivary glands, nasopharynx, nasal and paranasal sinuses, orbit, and meninges. Until 2006, only 36 cases of SFT had been reported in the oral cavity, which underlines the importance of the case reported recently in the Rev Esp Oral Cir Maxilofac.¹ Nevertheless, we have to clarify that, although very rare, cases of malignancy of intraoral SFT have been reported.^2,3 Shnayder et al.,² in 2003, referred a case of malignant TFS of the tongue that did not metastasize in 18 months of follow- up after aggressive surgery. More recently, in 2006, our group3 reported a case of malignant TFS located in the yugal mucosa. It exhibited an infiltrative pattern, high mitotic index, and strongly positive immunohistochemical pattern for CD- 34, CD-99, bcl-2 and vimentin. Despite its aggressive microscopic appearance, the case had a macroscopic aspect similar to the cases of SFT mentioned above. After enlarged surgical resection, no recurrence was observed in the two years after the intervention.

Pleural SFTs have a 23% probability of malignization but, in effect, they are exceptional in extrapleural locations.⁴ In most cases, malignant SFTs are hypercellular, with focal moderate or intense atypia, tumoral necrosis, abundant mitosis and infiltrating margins. The differentiation of benign and malignant SFT must be established on the basis of the presence of abundant mitoses, which are rare or absent in benign forms, and based on the presence nuclear atypia.

We recommend resection with ample surgical margins for the treatment of intraoral SFT with an aggressive histologic component. Some authors⁵ have recommended chemotherapy and postoperative irradiation in large tumors with involvement of surgical margins. As our colleagues correctly indicate,¹ long-term follow-up is fundamental due to the possibility of local, regional and remote recurrence, particularly if we consider that the malignancy of some rare cases has been established.

Raúl González-García¹; Luis Naval-Gías²; Jesús Sastre-Pérez³

¹F.E.A. Servicio de Cirugía Oral y Maxilofacial, Hospital Universitario Infanta Cristina, Badajoz. España
²F.E.A. Servicio de Cirugía Oral y Maxilofacial, Hospital Universitario La Princesa, Madrid. España
³F.E.A. Servicio de Cirugía Oral y Maxilofacial, Hospital Universitario La Princesa, Madrid. España

References

1. García de Marcos JA, del Castillo Pardo de Vera JL, Arroyo Rodríguez S, Galdeano Arenas M, Calderón Polanco J, Gracía de Marcos MJ, Valer Corellano J. Tumor fibroso solitario intraoral: análisis clinicopatológico e inmunohistoquímico. Rev Esp Cir Oral Maxilofac 2008;30:180-4.        [ Links ]

2. Shnayder Y, Greenfield BJ, Oweity T, DeLacure MD. Malignant solitary fibrous tumor of the tongue. Am J Otolaryngol 2003;24:246-9.        [ Links ]

3. González-García R, Gil-Díez Usandizaga JL, Hyun Nam S, Rodríguez-Campo FJ, Naval-Gías L. Solitary fibrous tumour of the oral cavity with histological features of aggressiveness. Br J Oral Maxillofac Surg 2006;44:543-5.        [ Links ]

4. Yamashita Y, Satoh T, Goto M. Solitary fibrous tumor of the tongue: a case report with immunohistochemical studies. Int J Oral Maxillofac Surg 2002;31:681-3.        [ Links ]

5. Veltrini VC, Etges A, Magalhaes MH, de Araujo NS, de Araujo VC. Solitary fibrous tumor of the oral mucosa—morphological and immunohistochemical profile in the differential diagnosis with hemangiopericytoma. Oral Oncol 2003;39:420-6.        [ Links ]