CASO CLÍNICO

 

Intraoral solitary fibrous tumor: clinical, pathologic, and immunohistochemical analysis

Tumor fibroso solitario intraoral: análisis clinicopatológico e inmunohistoquímico

 

 

J.A. García de Marcos¹, J.L. del Castillo Pardo de Vera², S. Arroyo Rodríguez³, M. Galdeano Arenas¹, J. Calderón Polanco⁴, M.J. García de Marcos⁵, J. Valer Corellano⁶

¹ Especialista en Cirugía Oral y Maxilofacial. Servicio de Cirugía Oral y Maxilofacial. Complejo Hospitalario Universitario de Albacete. Albacete, España.
² Especialista en Cirugía Oral y Maxilofacial. Servicio de Cirugía Oral y Maxilofacial. Hospital Universitario "La Paz". Madrid. España.
³ Especialista en Cirugía Oral y Maxilofacial. Jefe de sección del Servicio de Cirugía Oral y Maxilofacial. Complejo Hospitalario Universitario de Albacete. Albacete. España.
⁴ Especialista en Cirugía Oral y Maxilofacial. Jefe de Servicio de Cirugía Oral y Maxilofacial. Complejo Hospitalario Universitario de Albacete. Albacete, España.
⁵ Especialista en Estomatología. Práctica Privada. Madrid, España.
⁶ Especialista en Anatomía Patológica. Complejo Hospitalario Universitario de Albacete. Albacete, España.

Correspondence

 

 

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ABSTRACT:

Solitary fibrous tumors (SFT) are spindle cell neoplasms that most often originate from mesothelial lined surfaces. Intrathoracic tumors are more common and oral mucosal involvement is uncommon. Clinically, intraoral SFT is usually a painless, well delimited, slow-growing, mobile submucosal mass. Diagnosis is based on immunohistochemical and histopathologic analysis. Histologically, SFT is characterized by a variable provision of spindle cells, which generally are CD34-positive. Resection is the treatment of choice and long-term follow-up is recommended because recurrences and late metastases.
We present a case of intraoral SFT of the mandibular vestibular sulcus. One year after surgical resection, there were no signs of local or regional recurrence. The literature was reviewed.

Key words: Solitary fibrous tumors; Intraoral; Immunohistochemistry; CD34.

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RESUMEN

El tumor fibroso solitario (TFS) es una neoplasia de partes blandas compuesta por células fusiformes, que principalmente se origina en las superficies mesoteliales. Generalmente tiene una localización intratorácica y la afectación de la cavidad oral es excepcional. Clínicamente el TFS intraoral suele presentarse como una masa móvil, submucosa, no dolorosa, bien circunscrita, de lento crecimiento. El diagnóstico se obtiene mediante al análisis histopatológico e inmunohistoquímico. Histológicamente se caracteriza por una disposición variable de células fusiformes ovoides, generalmente positivas para el marcador CD34. El tratamiento de elección es la extirpación quirúrgica de la lesión, recomendándose un seguimiento postoperatorio a largo plazo por la posibilidad de aparición de recurrencias y metástasis tardías.
Presentamos un caso de TFS intraoral, localizado en el fondo del vestíbulo mandibular. Un año después de la resección quirúrgica de la lesión, no hay signos de recidiva local o regional. Asimismo, realizamos una revisión de la literatura.

Palabras clave: Tumor fibroso solitario; Intraoral; Inmunohistoquímica; CD34.

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Introduction

Solitary fibrous tumor (SFT) is a rare, spindle-cell, soft tissue neoplasm that originates mainly from mesothelial surfaces.^1-6 It was first described in 1931, by Klemperer and Rabin,⁷ as a pleural tumor. It has been known by other names, such as localized fibrous mesothelioma, localized fibrous tumor, solitary fibrous mesothelioma, submesothelial fibroma, and pleural fibroma.^1,5,12

Although SFT usually is located in the chest, cases have been described in almost every location in the body.^1-6,9,12,13 In the head and neck, SFT has been reported in the meninges, orbit, oral cavity, nose, paranasal sinuses, nasopharynx, parapharyngeal space, larynx, in the three major salivary glands, epiglottis, larynx, thyroid, skin, infratemporal fossa, and deep cervical soft tissues.^1-5,9,11,13 SFT rarely occurs in the oral cavity.^1,3,8,10 Clinically, intraoral SFT usually presents as a mobile, painless, well circumscribed, slow-growing submucosal mass of variable size and evolution.^1-4,8,11 The color and texture of the overlying mucosa usually is normal.^1,4 The tumor surface is generally smooth and white.¹¹ Clinically the differential diagnosis is made with lipoma, fibroma, vascular malformation, salivary gland neoplasm, mucocele, and granular cell tumor.^3,4

SFT is diagnosed on the basis of distinctive microscopic criteria, which vary and sometimes are similar to other tumors, and by immunohistochemical studies.^1-3,8 Histologically SFT is characterized by a variable disposition of spindle cells, which generally are positive for the CD34 marker.^2,4

The treatment of SFT is surgical tumor resection.^{1-3,6,8,10-12} All the cases of intraoral SFT reported in the literature have behaved benignly, so the prognosis is good.^2,3

 

Clinical case

A 37-year-old male patient consulted for a right paramandibular nodule, of 6 years’ evolution, that had increased in size in the last year. He said that the tumor appeared after a lower molar was extracted.⁴⁶

On examination, the patient had a nodule 1.5 cm in diameter in the vestibular sulcus, at the level of 45 and theoretical 46. The tumor was mobile, well delimited, of elastic consistency, and tender on palpation. The overlying mucosa was normal. Orthopantomography did not reveal mandibular pathology.

The tumor was resected under local anesthesia after identifying the mental nerve tract to preserve it (Fig.1).¹ Macrocospically, the tumor was nodular, well-delimited, whitish, and measured 2x1.5x1 cm. Microscopically, the tumor was formed by spindle cells of uniform appearance with poorly defined cytoplasmic limits, oval or round nuclei, and no mitotic figures or nuclear pleomorphism. Cells were arrayed randomly and interspersed with collagen fibers and isolated blood vessels (Fig. 2). There were no areas of necrosis or a hemangiopericytoid pattern. On the periphery, the tumor was delimited by a margin of connective tissue.

Immunohistochemically, tumor cells were intensely positive for vimentin, CD34, and bcl2 (Fig. 3), weakly positive for factor XIIIa and muscle-specific actin (1A4), and negative for S-100 protein, cytokeratins (CAM 5,2; AE1-3), desmin, and muscular actin (HHF35).

The postoperative period passed without complications and one year alter surgery there were no signs of local or regional recurrence.

 

Discussion

It was initially thought that the origin of SFT was in the mesothelial cells or submesothelial fibroblasts because the lesion affected the visceral pleura and other serosal locations. ^3,11,12 However, immunohistochemical and ultrastructural studies and tissue culture have demonstrated that the tumor cells lack mesothelial differentiation. Although the histogenesis of SFT is debated, it is believed that it may have a fibroblastic or myofibroblastic origin.^2,3,5,10-12 A mesenchymal origin is consistent with the documented finding that this tumor occurs almost everywhere in the body and the fact that both malignant and benign variants have been identified.^3,5

The histogenic origin is a specific population of interstitial dendritic spindle cells, CD34+, that are distributed in different tissues and organs, including the connective tissue of the oral mucosa.^1,3 These primitive mesenchymal cells can function as antigen-presenting cells or intervene in tissue repair.¹

Shimoyama et al.⁸ reviewed all the cases of oral SFT published in English and Japanese language journals up until 2002 and compiled only 47 cases. The mean age of patients was 51 years and women were predominant (30:18). The cheek was the predominant area of involvement, followed, in decreasing order, by the tongue, gums, palate, lip, vestibular sulcus, retromolar trigone, and mental region. Tumors had a mean size of 19.7 mm. All lesions were treated by simple surgical resection and there was no evidence of recurrence or metastasis in any case.⁸

The fact that some cases of SFT reported had a history of trauma in the area where the tumor later appeared means that trauma can be considered an etiological agent.^3,8 In the case presented here, the patient referred extraction of a molar adjacent to the tumor as a possible causal agent.

Although systemic manifestations (fever, chest pain, hypoglycemia, and osteoarthropathy) associated with large solitary fibrous tumors have been reported, these manifestations have not been reported in intraoral cases.^2-4

Histologically, SFT usually presents areas of increased cellularity and a randomly arrayed proliferative pattern, whereas other regions present isolated mitotic figures.⁸ The cellularity of SFT usually varies from one site to another and is inversely related to the amount of collagen.^1,8 Among the most common findings in SFT are hypercellular regions, a vascular pattern similar to that of hemangiopericytoma, and a wavy, nervoid appearance.^8,12

Immunohistochemically, most SFTs, independently of anatomic location, exhibit diffuse, moderate-to-strong positivity for CD34, bcl2, CD99, and vimentin. Factor XIIIa (although positive in most cases) appears in a small percentage of neoplastic cells.^2-4 In addition, the majority of SFTs are negative for S-100, smooth-muscle actin, desmin, factor VIII, muscle-specific antigen, cytokeratin, epithelial membrane antigen, and CD68.^2,3,6,10 The present clinical case exhibited intense positivity for vimentin, CD34, and bcl2; weak positivity for factor XIIIa and muscle-specific actin (1A4); and negativity for S-100 protein, cytokeratins (CAM 5,2; AE1-3), desmin, and muscular actin (HHF35).

Due to the wide histologic and immunohistochemical variety observed in SFT, this neoplasm must be differentiated from many benign and malignant soft-tissue tumors, such as benign or malignant fibrous histiocytoma, neurofibroma, neurilemmoma, myofibroma, leiomyoma, fibroma, spindle-cell lipoma, dermatofibrosarcoma protuberans, giantcell angiofibroma, and single-phase synovial sarcoma. The differential diagnosis with hemangiopericytoma is probably the most difficult.^2-6,11,12,14 The immunohistochemical profile may be useful in cases where morphologic differences are not clear, such as with neurilemmoma, neurofibroma, peripheral neural-sheath tumor, angioleiomyoma, and solitary myofibroma. In the case of fibrous histiocytoma, an exhaustive histologic study suffices to establish the differential diagnosis. Malignant cytological features also help to rule out leiomyosarcoma and fibrosarcoma.¹

Although all the cases of intraoral SFT reported have had a benign clinical and histologic behavior, atypical and malignant variants have been described in pleural and extrapleural locations.^2,3,13 It is estimated that 5% to 20% of pleural SFTs behave malignantly, with local aggressiveness, recurrence, propagation, and distant metastases. Reviews of extrathoracic SFTs have demonstrated that 10% of these tumors, including soft-tissue tumors, may have a malignant behavior.³ Consensus is lacking on the histologic criteria that define malignant clinical behavior in SFT. Atypical histologic findings include nuclear atypia, hypercellularity, mitotic figures > 4 per 10 high-power fields, necrosis, and absence of defined margins.^2-4,11 As the presence of histologic atypia does not predict aggressive clinical behavior, because even tumors with benign histologic characteristics can behave aggressively, it has been suggested that morphologic images and the pattern of clinical growth be considered when classifying these tumors. SFTs of the head and neck usually do not behave aggressively, although cases of high cellularity and high mitotic activity exist.^1,4

The treatment of choice is surgical tumor resection.^{1,3,4,6,8,10-12} Before surgery, selective embolization of the blood vessels of the tumor can be performed.¹⁰ In addition, neoadjuvant chemotherapy (doxorubicin and dacarbazine) and postoperative irradiation have been used in cases of large tumors with involvement of the resection margins after surgery.^4,11

Because of the possibility of recurrence and late metastasis, long-term follow-up of all patients operated for SFT is advised, regardless of the anatomic location of the tumor.^2-4,9-11

 

 

Correspondence:
J.A. García de Marcos.
C/ Antonio Acuña. Nº 10 5ºA izq.
28009 Madrid, España.
Email: pepio2@hotmail.com

Recibido: 07.12.2007
Aceptado: 07.03.2008

 

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