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Schwannoma of the oral cavity.Histological and immunohistochemicalfeatures

Sandra De Cássia Santana Sardinha1*

Aleysson Olímpio Paza2*

Pablo Agustin Vargas3*

Roger William Fernandes Moreira4*

Márcio de Moraes5*

1Resident Oral Maxillofacial Surgery2 Resident Oral Maxillofacial Surgery3Professor Oral Pathology4Professor Oral Maxillofacial Surgery5Professor Oral Maxillofacial Surgery* Piracicaba Dental School - UNICAMP

Received for publication: March 08, 2004Accepted: May 24, 2005

Correspondence to:Márcio de MoraesFaculdade de Odontologia de Piracicaba –UNICAMPAvenida Limeira, 901, AreiãoCEP: 13.414-903Caixa Postal: 52Piracicaba-SP, BrasilPhone: +55-19-3412-5326E-mail: mmoraes@fop.unicamp.br

AbstractSchwannoma is a relatively uncommon, slowly growing lesion that ismost commonly encountered in the nerve sheath. The mobile portionof the tongue is the most common site, followed by the palate, floor ofmouth, buccal mucosa, lips, and jaws. The present case report referea 13-year-old boy with a tongue mass that did not interfere with thespeech. The histopathology and immunohistochemistry study of theexcised lesion showed a Schwannoma of the tongue.

Key Words:neurilemoma, schwannoma, oral cavity, tongue ,immunohistochemistry

Braz J Oral Sci. July-September 2005 - Vol. 4 - Number 14

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Braz J Oral Sci. 4(14):806-809 Schwannoma of the oral cavity. Histological and immunohistochemical features

IntroductionSchwannoma has been defined as a benign, encapsulatedneoplasm that arises in the nerve fiber. This neoplasm iscomposed primarily of Schwann cells in a poorly collagenizedstroma1. The etiology is unknown, but it is postulated thatthe lesion arises by the proliferation of Schwann cells at onepoint inside the perineurium. The growth of this lesion willcause the displacement and compression of the surroundingnormal nerve tissue.The tumor may arise at any age. Some series have reportedthat the schwannoma is more common in adults, in contrastto the neurofibroma which tends to be more frequent in youngchildren2. Most reports suggest that the majority of tumorsare present between the ages of 10 and 40 years3-4. Someseries report a higher incidence of Schwannoma in the femalepopulation3, while others show a slight male predominance4.Clinically, the tumor appears as a smooth-surfaced, usuallypainless, soft-tissue swelling with intact overlying epithelium.There have been approximately 146 schwannomas reportedfrom the oral soft tissues3-5.The schwannoma is usually a solitary lesion. When multiple,however, they be associated with neurofibromatosis1. Thedifferentiation between schwannoma from neurofibroma isessential, because an apparently “solitary” neurofibromamay be a manifestation of neurofibromatosis. Fifteen tosixteen percent of pacients with neurofibromatosis willpresent malignant transformation in one or more lesions,contrary to schwannoma1.Histologically, the schwannoma is encapsulated and consistsof varying quantities of two types of tissues-Antoni A andAntoni B. The treatment for schwannoma is surgical excision.Recurrence after excision of schwannoma is rare. Malignantchange has been reported, however this is an extremely rarephenomenon.

Clinical CaseA 13-year-old boy was admitted to the Maxillofacial SurgeryService of the Campinas State University, São Paulo, Brazil,for treatment of a swelling on the tongue. The patient’smother stated the presence of painless, slow growing lesionfor the past few years. No problems with speeching orswollowing were reported. The lesion was founded during aroutine dental examination.Oral examination revealed a yellowish, well circunscribedmass on the vertix of the tongue, approximately 1.4cm x 0.6cmx 0.6cm in size. The was no tender to palpation and there wasno evidence of paresthesia or ulceration (Figure 1).Macroscopically, the lesion was grossly similar to a lipoma.The patient was otherwise healthy without significant pastmedical history. The mass was excised under local anesthesiawithout complication (Figure 2). Microscopically, theschwannoma was uncapsulated and consisted of typicalAntoni A zones admixed with Antoni B zones. Antoni A tissue

was predominant in the present case (Figure 3).Immunohistochemical studies were positive for S-100 protein(policlonal; 1:2000 dilution; none antigen retrieval; Dako;Denmark) mainly in Antoni A areas (Figure 4). The vimentantibody (V9; 1:6000 dilution; heat induced epitope retrieval;Dako; Denmark) was diffusely positive (Figure 5), and theanti-CD57(LEU-7; Dako; Denmark) was found to be negative.After 12 months of follow-up, no recurrence has beendetected (Figure 6).

Fig. 1 - Mass on the tongue’s vertix, well circumscribe, light yellow,and no ulceration.

Fig. 2 - Surgical excision under local anesthesia

Fig. 3 - View of typical Antoni A zone that is characterized bypalisading of the spindle-shaped schwannoma cells.(Hematoxylinand eosin stain. Original magnification, x200).

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Fig.4 - Note the immunohistochemical positivity for S-100 proteinin the schwannoma. (Original magnification, x400).

Fig. 5 - Diffuse positive immunohistochemical staining for vimentinin the schwannoma. (Original magnification, x400).

Fig. 6 - Clinical view of the tongue, after one year of follow-up.

DiscussionSchwannoma is a benign tumor, apparently derived from theSchwann cells, which may arise from any myelinated nervefiber6-7.The tumor is composed primarily of schwann cells ina poorly collagenized stroma1. This lesion is not commom inthe oral cavity. The schwannoma is usually a solitary lesion,but can be multiple lesions when associated withneurofibromatosis1.

Wright and Jackson1, reported 146 cases of schwannoma ofthe oral cavity soft tissue. Of those, 52% occurred in thetongue, 19.86% in the buccal or vestibular mucosa, 8.9% inthe soft palate, and the remainder 19,24% were in the gingivaeand lip.Schwannomas of the hypoglossal nerve are rare tumors.These tumors are seldomly found in the sublingual space.when present, usually involves the most peripheral segmentof the hipoglossal nerve6.Histologically, schwannomas are descried as Antoni Atype or Antoni B. Antoni type A present a parallelarragement of fibrocyte-like cells, and Verocay bodies.Antoni B, is less cellular and shows microvacuolation ofthe intercellular substance. Flickinger et al.8, reported thatin most tumors both cell types are present as reported inthe present case.Chrysomali et al.3, reported that schwannomas consistentlyshowed positive staining for S-100 protein in most of thetumor cells. The staining intensity was greater in cells inthe Antoni A tissue compared with that seen in the AntoniB tissue similarly to our case. On the other hand theimmunorectivity for CD57 antibody was negative in ourreport. Chrysomoli et al.9, showed CD57-positive cells 0,1%to 10% in schwannomas and neurofibromas.Ancient schwannoma, a variant of schwannoma, was firstdescribed in the thorax by Ackerman and Taylor, in 19511.This lesion contain both Antoni A and Antoni B pattern,with pleomophic nuclei , some of which may behyperchromatic. Area of hemorrhage hemossiderinaccumulation as well as mitotic figures may be seen1.Redman et al.10, reported a case of cellular schwannoma ofthe mandible. This tumor differs from classic schwannoma,by its increased cellularity, nuclear pleomorphism andhyperchromatism, lack of Verocay bodies, and frequentlyhigher mitotic activity10.Lipomas, hemangiomas, eosinophilic granuloma,epidermoid and dermoid cysts, epithelial hyperplasia,granular cell tumor, leyomioma, lymphangioma, are someof the lesions included in the differential diagnosis ofschwannoma1. López and Ballestin11, reported that thehistological pattern of schwannoma is easily recognizable.The management of schwannoma requeres completsurgical excision of the lesion. Schwannoma rarely recidiveand not respond to radiation therapy1,12.The conclusion is that the benign Schwannoma representa pathology which are often not taken into account duringclinical pratice. Differencial diagnosis must be made inrelation to numerous benign neoformations basead onepitelial and connective tissue and, malignant tumors.Immunohistochemical features can be useful in determingneural differentiation. Anti-S-100 protein is probably thesingle best antibody for this case. Treatment of theSchwannoma is complete surgical excision.

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References1. Wright BA, Jackson D. Neural tumors of the oral cavity. A

review of the spectrum of benign and malignant oral tumorsof the cavity and jaws. Oral Surg Oral Med Oral Pathol 1980;49: 509-22.

2. Shklar G, Meyer I. Neurogenic tumors of the mouth and jaws.Oral Surg Oral Med Oral Pathol 1963; 9: 1075-93.

3. Cherrick HM, Eversole LR. Benign neural sheath neoplasmof the oral cavity. Oral Surg Oral Med Oral Pathol 1971; 32:900-9.

4. Hatziotis J C, Asprides H. Neurilemoma (schwannoma) ofthe oral cavity. Oral Surg Oral Med Oral Path 1967; 24:510-27.

5. Oberman HA, Sullenger G. Neurogenous tumors of the headand neck. Cancer 1967; 20: 1992-2001.

6. Drevelengas A, Kalaitzoglou I, Lazaridis N. Sublingualhypoglossal neurilemmoma. Case report. Aus Dent J 1998;43: 311-4.

7. Kolls SO, McGinnis Jr JP, Quon D, Miss J. Multinodular versusplexiform neurilemoma of the hard palate. Report of a case.Oral Surg Oral Med Oral Pathol 1994; 77: 154-7.

8. Flickinger FW, Lozano RL, Yuh WTC, Sachs MA.Neurilemmoma of the tongue: MR findings. J Comp AssistTomogr 1989; 13: 886-8.

9. Crhysomaly E, Papanicolaou SI, P. Dekker NP, Regezi JA.Benign neural of the oral cavity. Oral Surg Oral Med OralPathol 1997; 84: 381-90.

10. Redman RS, Guccion JG, Spector CJ, Keegan BP. CellularSchwannoma of the mandible: A case report with ultrastructuraland immunohistochemical observations. J Oral MaxillofacSurg 1996; 54: 339-44.

11. López JI, Ballestin C. Intraoral schwannoma. Aclinicopathologic and study of nine cases. Arch Anat CytolPathol 1993; 41: 18-23.

12. Okura A, Shigemori M, Abe T, Yamashita K K, Noguchi, S.Hemiatrophy of the tongue due to hypoglossal schwannomashown by MRI. Neuroradiol 1994; 30: 239 40.

Braz J Oral Sci. 4(14):806-809 Schwannoma of the oral cavity. Histological and immunohistochemical features