Solitary Neurofibroma of Palatine Tonsil- A Case Report

Introduction

Neurofibromas have been commonly described in the head and neck region with its presentation in the soft tissues of the lateral cervical region and in the pharynx [1]. However its description in oral cavity, pharynx and palatine tonsils are extremely rare. Neurofibromas, Schwannomas and perineuromas have been described under benign peripheral nerve sheath tumors (BPNSTs) and are regarded as distinct entities [2]. Here we report a rare case of solitary neurofibroma of palatine tonsil in an 18 year old Indian female patient, whom we believe to be the third such case reported in world literature till date.

Discussion

Neurofibromas of the head and neck usually manifest as deep seated tumors while its presentation in the oropharyx is extremely rare. The risk of malignant transformation has been reported between 5-12%, especially when associated with Von Recklinghausens disease [3]. Amongst BPNSTS; schwannomas, neurofibromas and perineuroma are regarded as distinct entities [2]. Neurofibromas have been suggested to have a mixed or hamartomatous origin owing to the presence of distinct cell types which are derived from both neural crest and mesenchymal precursors [4]. Neurofibromas in contrast to schwannomas, are less cellular, looser in texture and don’t exhibit the characteristic pattern of alternating Antony A and Antony B. However various electron microscopic, immunohistochemical and tissue culture studies support an alternative hypothesis that neurofibromas may result from divergent differentiation of a single cell type [5]. This is supported by the documentation of somatic loss of heterozygosity and mutation of the neuro bromatosis 1 (NF1) gene in NF1- associated neurofibromas [6]. By definition, solitary neurofibromas constitute 90% of all neurofibromas and affect patients who do not have neurofibromatosis [7]. They affect men and woman equally and mostly appear during the third and fourth decades of life.

Neurofibromas have been described in various forms: cutaneous neurofibromas (both localized and diffuse types), intraneural neurofibromas (localized and plexiform), massive soft-tissue neurofibromas (diffuse and plexiform), and visceral neurofibromas (solitary or multiple, sporadic or associated with neurofibromatosis [von Recklinghausen's disease]). The clinical presentation and gross appearance of these forms differ considerably despite of their common cellular makeup. The diagnostic workup should include a search for more than one neurofibroma and identification of one or more clinical features such as café au lait macules, cutaneous and mucosal nodules. Family history of similar lesions should be solicited. Other investigations should include pure- tone audiometry to exclude bilateral neural hearing loss, an ophthalmologic examination to look for Lisch nodules (iris hamartoma), CT or MRI of the head and neck to search for other tumors (e.g., glioma, meningioma, and astrocytoma), and abdominal scanning for pheochromocytoma. Genetic tests for gene mutations might be performed if feasible. An extensive study of literature yielded only 2 cases of solitary neurofibroma limited to the oropharyx. The first case was reported in 2002 by Surwald, et al. reported the first case of solitary neurofibroma of the palatine tonsil, which occurred in a 28-year-old white man in the United Kingdom [8]. The second case was reported in 2007 by Madhumita, et al. in a 49 year old Indian woman [9].

Conclusion

Neurofibromas are usually solitary tumors, however upto a tenth of patients have multiple lesions [8]. In the head and neck, neurofibromas usually present as a painless mass invariably compressing surrounding vital structures and hence interfering with phonation, deglutition or respiration requiring early surgical intervention.