Solitary neurofibroma of the palatine tonsil: a case report

Ear, Nose & Throat Journal, Dec, 2007 by Kumar Madhumita, Ajit Nambiar, Parameswaran Prathapan

Abstract

We present a rare case of a benign tumor of the tonsil in a 49-year-old woman. The tumor was excised in its entirety, and the patient's postoperative course was uneventful. No evidence of recurrence was detected during follow-up. Although some sporadic cases of tonsillar schwannoma have been reported, to the best of our knowledge this is only the second case of a solitary neurofibroma of the palatine tonsil to be reported in the English-language literature.

Introduction

Although the head and neck region is a common location for benign peripheral nerve sheath tumors, neurofibromas of the oral cavity, pharynx, and palatine tonsil are extremely rare. Some sporadic cases of schwannomas of the tonsil have been documented, (1) but to the best of our knowledge only 1 case of a solitary neurofibroma of the tonsil has previously been reported in the English-language literature. (2) In this article, we describe what we believe is only the second such case. We also discuss the clinical and histopathologic features of solitary neurofibroma, and we review its management.

Case report

A 49-year-old woman presented with a 6-month history of dysphagia and odynophagia. She also complained of pain radiating to the left ear. Examination revealed a substantial left tonsillar enlargement that extended to the vallecula. No pigmented lesions or any other cutaneous or mucosal stigmata suggestive of neurofibromatosis were noted. The patient had no family history of neural tumors.

Computed tomography (CT) of the neck showed a 3.5 x 2.2-cm solid oval mass in the pharyngomucosal space in the area of the left tonsil (figure 1). The lesion exhibited well-defined margins. Medially, the lesion was in relation to the mucosa of the pharynx, and laterally, it was in relation to the submandibular gland.

The patient was taken up for a biopsy of the mass, which was reported as a neurofibroma. She underwent complete excision of the tumor (figure 2). Her postoperative recovery was uneventful.

Microscopy revealed that the unencapsulated, circumscribed tumor was made up of interlacing bundles of spindle cells with hyperchromatic, serpentine nuclei (figure 3). These cells were intermixed with foci of dense bundles of collagenous fibers. Immunohistochemistry showed positivity for S-100 protein in the Schwann cells (figure 4).

During follow-up, the patient exhibited no other signs of head and neck neurofibromatosis, and an ophthalmologic examination detected no Lisch nodules in the iris. At the 1-year follow-up, no sign of recurrence was evident.

Discussion

Neurofibromas of the head and neck usually manifest as deep-seated tumors. The risk of malignant transformation is significant--between 5 and 12%. (3) Neurofibromas of the oropharynx are extremely rare. An extensive search of the literature yielded only 1 case of a solitary neurofibroma arising from the soft palate; this patient presented with insidious tumor enlargement that had led to difficulties in swallowing and speech. (4) In 2002, 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. (2) In 1975, Pen'kovskii reported a neurofibroma of the tonsil in a 61-year-old Russian woman with multiple neurofibromas. (5)

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Several forms of neurofibromas have been described: 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 1 [von Recklinghausen's disease]). (6) Despite their common cellular makeup, the clinical presentation and gross appearance of these forms differ considerably.

The diagnostic workup includes a search for more than one neurofibroma and identification of clinical features such as cafe au lait macules and cutaneous and mucosal nodules. Information on a 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 can be performed if feasible.

By definition, solitary neurofibromas affect patients who do not have neurofibromatosis. Solitary neurofibromas account for 90% of all neurofibromas. (7) They affect men and women equally, and most appear during the third and fourth decades of life. These lesions are usually painless, and they grow slowly. The chance of malignant transformation is extremely low. (7)

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A solitary neurofibroma must be differentiated from a schwannoma. A schwannoma is encapsulated, eccentric to the nerve, and composed of Schwann cells. (6) A neurofibroma incorporates the nerve (which is infrequently identified), and it is composed of Schwann cells, perineural-like cells, fibroblasts, and transitional cells. (6)