Abstract

Neurilemmomas of the tongue are uncommon. When they do occur, treatment is simple. However, diagnosis is invariably delayed because of the vagueness of symptoms. We encountered 2 cases of this unusual tumor within weeks of each other. In 1 of these cases, the definitive diagnosis was delayed because of the atypical clinical picture--that is, an abscess in the tongue that had caused respiratory distress. We describe our management of these 2 cases, and we discuss what has been published in the literature regarding the presentation, diagnosis, histopathology, treatment, and prognosis for patients with glossal neurilemmoma.

Introduction

Neurilemmomas (schwannomas are benign tumors of nerve sheath origin that are derived from Schwann cells. They can arise in any myelinated nerve fiber. About 25% of neurilemmomas occur extracranially. (1) Of these, only 1% are of intraoral origin, and of those, glossal tumors are even rarer. (1) Neurilemmomas account for only 1% of all benign tumors in the oropharynx and oral cavity. (2)

We encountered 2 cases of neurilemmoma of the tongue within a 3-week period. Although the 2 patients had similar demographic and clinical profiles, 1 of them had an unusual presentation--to wit, a lingual abscess with respiratory distress.

Case reports

Patient 1. A 30-year-old man presented to the emergency department at Safdarjung Hospital with a chief complaint of swelling of the tongue associated with breathing and swallowing difficulties; he also had a high-grade fever. The patient was referred to the ENT department, where a detailed examination revealed that he was indeed stridulous and febrile. His submandibular and upper deep cervical lymph nodes were enlarged and tender. Inspection of the oral cavity revealed that the tongue was swollen to the point that it prevented visualization of the oropharynx; pooling of saliva was also noted.

Urgent computed tomography (CT) of the pharynx and neck revealed the presence of a large abscess that involved the left side of the base of the tongue and encroached on the oral tongue, causing significant airway compromise (figure 1, A). Before the patient could undergo urgent tracheotomy and drainage, the abscess spontaneously ruptured from the floor of the mouth on the left side (figure 1, B). The pus was sent for culture and sensitivity and for acid-fast bacilli (AFB) staining.

In the meantime, the patient was administered antibiotics, and he improved over the course of the next week. On hospital day 8, he was successfully decannulated and discharged. AFB staining was negative, as was an enzymelinked immunosorbent assay for the presence of human immunodeficiency virus.

Six weeks later, the patient returned with a similar swelling of the left side of the tongue base. He was afebrile and was not experiencing respiratory embarrassment. Contrast-enhanced CT of the left tongue base detected a nonenhancing soft-tissue mass with an area of central necrosis.

Routine surgery was planned with the aim of obtaining a transoral biopsy specimen. The well-encapsulated mass was easily dissected in toto, and the specimen was sent for histopathology. No associated nerve could be identified intraoperatively. The pathologist reported that the mass was a neurilemmoma with a mixture of Antoni A and B areas; nuclear palisading and Verocay bodies were evident (figure 1, C). Additional immunostaining with S-100 protein was positive, confirming the neural origin of the tumor.

At the 9-month follow-up, the patient remained symptom-free. He was subsequently lost to follow-up.

Patient 2. Another 30-year-old man presented to our department's outpatient clinic with a 2-month history of a gradually enlarging, painless lump in the right side of his mouth. He reported no dysphonia, swallowing difficulty, paresthesia, or taste disturbance associated with the lump.

The general physical examination did not reveal anything of significance. Examination of the oral cavity revealed a single 3 x 3-cm pedunculated mass. A slight degree of superficial ulceration was seen on the superior surface arising from the right tonsillolingual sulcus and adjacent tongue base on the right side. The tonsils, left side of the tongue base, vallecula, and endolarynx were normal. The results of routine investigations were normal.

The patient was taken to the operating room for excision of the mass under general anesthesia. The tumor was easily removed from the pedicle (figure 2). The histopathology report identified the specimen as a neurilemmoma. At the 6-month follow-up, the patient remained asymptomatic.

Discussion

Neurilemmomas have a distinct tendency to originate in the head and neck region. Most are solitary, slowly growing lesions. Usually well encapsulated, they may be attached to the nerve from which they arise. (3) Intraorally, they may arise in either bone or soft tissue; in the latter case, they usually appear as smooth submucosal swellings.

According to Chhatbar, (4) lingual neurilemmomas are most common in men in the third decade of life. In contrast, a female preponderance has been reported by Lucas (5) and by Enzinger and Weiss. (6) Other authors have reported an equal distribution between the sexes)

The diagnosis of neurilemmoma is established only by histopathology. Because these are uncommon tumors with minimal and nonspecific symptoms (dysphagia, discomfort, sometimes dyspnea, and occasionally ulceration and pain), it is not possible to differentiate them clinically from other benign intraoral tumors such as fibroepithelial polyps, fibromas, benign salivary gland tumors, and lipomas. (1,3) The reported duration of symptoms varies from weeks to years. Some cases are discovered incidentally.

Histologically, neurilemmomas exhibit a distinct pattern of alternating areas of compact spindle cells (Antoni A areas) and spindle or oval cells arranged haphazardly in a loose matrix (Antoni B areas). Degenerative changes, such as necrosis and cyst formation, are common. In highly differentiating areas, there may be nuclear palisading and the formation of Verocay bodies, as was seen in our patient 1. These oval-shaped bodies are formed by the alignment of two rows of nuclei and cell processes. (6) The diagnosis is confirmed by immunostaining with S-100 protein, which helps differentiate neurilemmomas (consistent expression with S-100 protein) from neurofibromas (variable expression).

The definitive treatment is simple excision, which is easily accomplished because of the tumor's encapsulated nature. Steps to preserve the associated nerve are occasionally necessary. If the tumor is completely excised, it will not recur. Malignant transformation to a fibrosarcoma is rare. (7) Because neurilemmomas are extremely radioresistant, radiotherapy has no role in their management.

In conclusion, neurilemmoma is not usually considered as an initial diagnosis in a case of a painless, slowly growing nodule or swelling in and around the oral cavity, and it may not even be included in the differential diagnosis. Therefore, a greater awareness of this tumor should result in more rapid diagnosis and treatment--and perhaps more documentation of cases in the medical literature.