Comparative ultrastructural and immunohistochemical study of perineurioma and neurofibroma of the oral mucosa
Introduction
Peripheral nerves consist of axons and ensheathments. Nerve sheath compartment is organized into three layers: endoneurium, perineurium and epineurium. They contain an assorted number and forms of supportive cells, including Schwann, perineurial (PN) and fibroblastic cells. A functionally specialized perineurium lies at the interface between the axon-Schwann cell units-investing endoneurium and a fibrovascular epineurium.1 PN cells differ from the inner most Schwann cells at the ultrastructural level by virtue of their long thin, bipolar cytoplasmic processes, numerous pinocytotic vesicles, discontinuous basal lamina, subplasmalemmal electron-dense plaques and well-developed tight junctions.[2], [3], [4] An epithelial membrane antigen (EMA)-positive immunophenotype is also accepted as additional evidence of PN differentiation in the setting of S-100 protein negativity.[1], [4], [5] These unique characteristics are never associated with endoneurial fibroblasts.1
Theoretically, neoplastic proliferation may occur independently from Schwann, PN or endoneurial fibroblastic cells; however, most peripheral nerve sheath tumors are undoubtedly schwannian in nature.1 Besides the two main forms, schwannoma and neurofibroma (NF), the term perineurioma, a third category of nerve sheath tumor entity, was advanced recently.[1], [5], [6] Because of the genuine rarity and considerable difficulty in the diagnosis, the existence of intraoral lesions does not appear to be widely appreciated.[7], [8], [9], [10], [11], [12] The purpose of the present study is to review the ultrastructure of gingival soft tissue perineurioma (STP) in some detail and to compare its cellular characteristics with classical NF which show a substantial participation of PN cells.[2], [3], [4], [5], [13], [14], [15], [16], [17], [18]
Section snippets
Materials and methods
STP case was a 59-year-old woman with a 2-month history of a painless, polypoid, soft nodule, 1.5 cm in greatest diameter, located on the palatal gingiva of the right upper first molar. Seven cases of intraoral solitary NF were available for comparative study. Formalin-fixed and paraffin-embedded sections were submitted for immunohistochemical analysis, including EMA (E29, 1:100; Dako, Glostrup, Denmark), S-100 protein (1:2000; Dako) and CD34 (My10, 1:100; Becton Dickinson, San Jose, CA).
Results
Submucosal STP presented with sharp circumscription but was not encapsulated on any side (Fig. 1(A)). The myxocollagenous tumor was composed of hypocellular interlacing fascicles of spindle to oval cells with wavy, wrinkled nuclei (Fig. 1(B)). There was no associated nerve within the lesion. Lesional cells showed diffuse membrane immunoreactivity for EMA (Fig. 1(C)), but were completely negative for S-100 protein and CD34. As shown in Fig. 2, tumor cells were spindle or stellate with irregular
Discussion
NF is formed by a complex proliferation of Schwann, PN, endoneurial fibroblastic and intermediate cells.[1], [4], [13], [14], [15], [16], [17], [18] With an average of about 36%,18 up to 87% of lesional cells were schwannian in nature.13 Although controversy exist regarding to what degree PN cells contribute to the formation of NF, they are an important neoplastic component.[2], [3], [4], [15] It is estimated that from 0.7% to 31% of the constituent cells were PN lineage.[13], [18] In a
References (31)
- et al.
Intra-osseous soft tissue perineurioma of the inferior alveolar nerve
Oral Oncol.
(2002) - et al.
Intraneural perineurioma not restricted to major nerves
Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod.
(2003) - et al.
Benign neural tumors of the oral cavity. A comparative immunohistochemical study
Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod.
(1997) - et al.
Immunohistochemical demonstration of EMA/Glut1-positive perineurial cells and CD34-positive fibroblastic cells in peripheral nerve sheath tumors
Mod. Pathol.
(2003) - et al.
Intraosseous benign neural sheath neoplasms of the jaws
Oral Surg. Oral Med. Oral Pathol.
(1977) - et al.
Intraosseous neurofibroma of the jaws
Int. J. Oral Surg.
(1978) - et al.
Primary extracranial meningioma of the mandible: a report of 2 cases and a review of the literature
Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod.
(2001) - et al.
Tumors of the peripheral nervous system
(1999) - et al.
Peripheral nerve sheath tumors: an electron microscopic study of 43 cases
Cancer
(1982) Peripheral nerve sheath tumors
Ultrastruct. Pathol.
(1985)
The enigmatic perineurial cell and its participation in tumors and in tumorlike entities
Ultrastruct. Pathol.
Perineuriomas: perineurial cell neoplasms with distinctive extra- and intra-neural forms
Adv. Anat. Pathol.
Soft-tissue perineurioma. Evidence for an abnormality of chromosome 22, criteria for diagnosis, and review of the literature
Am. J. Surg. Pathol.
A case of central perineurioma (Lazarus and Trombetta) of the mandible
J. Nihon. Univ. Sch. Dent.
Reticular perineurioma. A distinctive variant of soft tissue perineurioma
Am. J. Surg. Pathol.
Cited by (36)
Perineurioma of the Tongue: A Case Report and Review of the Literature
2019, Journal of Oral and Maxillofacial SurgerySolitary intraosseous neurofibroma: Report of a rare entity
2018, Journal of Oral and Maxillofacial Surgery, Medicine, and PathologyOral focal mucinosis of the tongue: A rare clinical entity?
2017, Oral and Maxillofacial Surgery CasesOral perineurioma: clinicopathologic features from two cases and review of literature
2017, Oral Surgery, Oral Medicine, Oral Pathology and Oral RadiologyCitation Excerpt :Follow-up of the reported cases showed that all cases showed no evidence of local recurrence after a mean interval of 19 months (range 4-68 months). There are 22 reported cases of oral EPNs in the English language literature since the first description in 1981, including the present case (Table II).4,5,8,9,20,22,23,41-48 In our cases, females were affected in 14 cases (female/male ratio 2:1), and the mean age of patients at diagnosis was 39 years (range 7-70 years).
Diagnostic Pathology: Head & Neck
2017, Diagnostic Pathology: Head and NeckUnilocular radiolucency of the mandible
2014, Oral Surgery, Oral Medicine, Oral Pathology and Oral RadiologyCitation Excerpt :One case was an intraneural perineurioma17 and the other six cases (including the present case) were extraneural STPs.13 Similar intraosseous mandibular lesions with the light microscopic morphology of STP have been reported as neurofibroma or extracranial meningioma.1 Recent re-examination of one of these cases18 with immunohistochemical IHC markers showed this “extracranial meningioma” to be an STP.13