Atypical central neurilemmoma of the mandible James Murphy, D.M.D., M.S.,” and John L. Giunta, D.M.D., M.S.,** Boston, Mass.

TUFTS L’NIVERSITY SCHOOL OF DENTAL IMEDICINE

Neurilemmomas arising within the jawbones are rare. Most occur in the mandible as slowly growing

enlargements that may or may not be painful; radiographically, they are large single or multiloculated

radiolucencies mimicking other benign jaw lesions. The histology is characteristic, with Antoni A and B

tissues and a well-defined capsule. This article reports an unencapsulated neurilemmoma of the mandible

and reviews and summarizes the features of the central neurilemmomas in the literature.

(ORAL SURG. ORAL MED. ORAL PATHOL. 59:275-278, 1984)

T he neurilemmoma (schwannoma) is a benign neural tumor derived from Schwann cells. Whereas a large percentage of nerve sheath tumors arise in the head and neck, a very small number occur intraor- ally. Even more rare are the oral intraosseous neuri- lemmomas.1-6 The most common site for intrabony neural tumor is the mandible, with the neurofibroma being more common than the neurilemmoma. The neurilemmoma is differentiated from the neurofibro- ma by having a more organoid tissue structure, the presence of a capsule, lack of recurrence, and lack of malignant transformation.7-9

The purpose of this article is to review the litera- ture and to add an unusual case of the rare intraman- dibular neurilemmoma.

REVIEW OF THE LITERATURE

Table I shows a listing of thirty-one intraosseous (central) nemilernmomas reported, including the present case, in several reviews1-6*8 and more recent articles.‘0-‘2 The following features of intrabony oral neurilemmomas are based on these cases.

Intrabony neurilemmomas occur predominantly in the mandible (twenty-nine in the mandible; two in the maxilla), particularly the posterior segment of the body and the ramus. Three cases have been confined to the symphysis of the mandible. Informa- tion on sex and age is available in twenty-six of the thirty-one cases. There is a female predilection, with

*Formerly, Assistant Clinical Professor, Oral and Maxillo-Facial Surgery, Tufts University School of Dental Medicine; at present Chief, Veterans Administration Medical Center, Philadelphia, Pa. **Professor of Oral Pathology.

Table I. Reported cases of central neurilemmomas

Author Year Age Sex Site

Zilkens 1937 Schroff 1945 Baetz and Shackelford 1951 Herrmann 1951 Spilka 1953 Aprile 1955 Helsham 1956 On0 1958 Bruce 1959 Svejda 1959 Sampter, Vellios, Shafer 1960 Ackerman 1962 Faraone 1963 Friedman 1964 Okano and others 1965 Fawcett and Dahlin 1967

Morgan and Morgan 1968 Hardt and Hardt 1972 Shimura and others 1973 Sugimura and others 1974 Swangsilpa and others 1976 Ellis and others 1977

Rengaswamy Barker and Dunlap Satterfield and others Schofield and Gardner Murphy and Giunta

1978 1979 1981 1981

17 48 43

39

72

64 7

20

72 18

64 25 19 65 23 49 44 II 31 30 36 12 84 28 16 28

M Mandible F Mandible F Mandible - Mandible M Mandible - Mandible F Mandible - Mandible F Mandible F Mandible F Mandible - Mandible M Mandible F Maxilla - Maxilla F Mandible M Mandible F Mandible M Mandible F Mandible M Mandible F Mandible M Symphysis F Mandible F Mandible F Mandible M Symphysis F’ Mandible M Symphysis F Mandible M Mandible

a 1.6: 1 female-to-male ratio. The age range is 7 to 84, with an average age of 37. Seventy-seven percent of the patients were below the age of 50 at the time of diagnosis; 46% were below the age of 30.

275

276 iMurphy and Giunta Orai Surg. March, 1985

Fig. 1. Panoramic radiograph showing expansile, irregular radiolucency of mandible between canine and premolars. There is prominent external resorption of the roots of the premolars, and the lesion extends to the inferior border which shows a periosteal radiopaque mass.

Fig. 2. Neurilemmoma showing spindle-shaped cells with palisading forming Verocay bodies of the Antoni A tissue component. (Hematoxylin and eosin stain. Magnification, x210.)

Clinically, neurilemmomas appear mainly as an expansion of the jawbone of several centimeters. However, there may be pain or paresthesia, with or without swelling. Radiographically, they are unicys- tic or multiloculated, well-outlined radiolucencies suggesting a benign process such as an odontogenic lesion. Some have been poorly defined. External resorption of adjacent roots is a common finding, and dystrophic calcification within the radiolucency4 has been described.

Histologically, the neurilemmoma is almost always encapsulated. Nerve tissue may be found in

the outer aspect of the capsule. The body of the tumor is composed of two distinct tissue types. The Antoni A tissue has palisading nuclei surrounding homogenous, hyalinized, anuclear, fibrillar areas; the unit is called a Verocay body. The Antoni B tissue is a looser, nonorganoid (no Verocay bodies) mass of elongated cells similar to neurofibromas. It may have lipophages with a microvesicular pattern and thick- ened blood vessels with deposits of hemosiderin pigment.‘, 7

The treatment is complete conservative surgical enucleation with periodic follow-up examination.

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Atypical central neurilemmoma of mandible 277

Fig. 3. Neurilemmoma with Antoni A. and Antoni B tissues plus hemosiderin pigment near blood vessel, (Hematoxylin and eosin stain. Magnification, X210.)

Fig. 4. Neurilemmoma with many xanthoma cells admixed with Antoni B tissue. (Hematoxylin and eosin stain. Magnification, X210.)

Recurrence is rare compared to the neurofibroma.4 However, recurrence after incomplete removal of a soft-tissue neurilemmoma has been reported.13 Thus, thorough curettement is most appropriate. The extent of the iesion at diagnosis may indicate more radical procedures, including removal of teeth and bone resection. Very rare, malignant transformation of an encapsulated neurilemmoma of the wrist has been reported9

CASE REPORT

A 28-year-old white man was referred for evaluation of a “Cyst” noted on dental radiographs in the premolar

region of the right mandible. There was no pain or paresthesia. The adjacent canine and premolar teeth, though not sensitive to percussion, did not respond to pulp testing. There was significant exljansion of the buccal bony plate, as well as an unusual osteophytic reaction along the inferior border of the mandible. The remainder of the physical examination revealed no abnormalities.

A panoramic radiograph revealed a unilocular, well- defined radiolucency of the right mandible with a nodular 1 cm radiopacity expanding the inferior border at the base of the lesion. There was partial external root resorption of the canine and particularly of the premolars (Fig. 1).

Aspiration of the lesion yielded nothing abnormal. With the patient under local anesthesia and intravenous and

278 Murphy and Giunta Oral Surg. March, 1985

inhalation sedation, and incision was made along the attached gingiva from the canine to the second molar. The flap was elevated, and the buccal bone was easily peeled away from the lesion. No capsule was identified. The tissue that was curetted from the bony cavity was soft, friable, and yellow to gray. The entire mass of tissue was excised,

and the bone cavity was curetted cleanly. The neurovascu- lar bundle was lying free and intact along the inferior buccal aspect of the cavity. The cavity was thoroughly irrigated with saline solution and packed with iodoform ribbon gauze, and the wound was sutured.

Histologically, the tissue was nonencapsulated, and composed of palisading cells within loosely arranged tissue with hemosiderin pigment near blood vesseis. Also noted were accumulations of xanthoma cells admixed with the less organized tissue. The diagnosis was neurilemmoma (Figs. 2 to 4).

One week following the surgical procedure the gauze packing was removed. The patient reported no paresthesia of the right inferior alveolar nerve distribution. Radio- graphs at 3 and 6 months revealed the bony cavity to be filling in normally.

DISCUSSION

The lesion in this case was not typical of previously reported neurilemmomas in that it was not encapsu- lated and there was a peripheral osteophytic reac- tion.

Concern that this lesion might represent a malig- nant counterpart of the benign neurilemmoma was considered. The slow growth, the lack of pain or paresthesia, and the cystic appearance did not seem consistent with a more aggressive tumor. The histo- logic appearance was benign. Despite the lack of a capsule, and because of the typical histologic pattern for a neurilemmoma, it is expected that the healing will continue to be uneventful.

REFERENCES

1. Fawcett KJ, Dahlin DC: Neurilemmoma of bone. Am J Clin Path01 47: 759-766, 1967.

2. Eversole LR: Central benign and malignant neural neoplasms of the jaws. J Oral Surg 27: 716-721, 1969.

3. Shimura K, Allen C, Kinoshita Y, Takaesu T: Central neurilemmoma of the mandibie: report of case and review of the literature. J Oral Surg 31: 363-367, 1973.

4. Ellis GL, Abrams AM. Melrose RJ: Intraosseous benign neural sheath neoplasms of the jaws. ORAL SURC ORAL MED ORAL PATHOL 44: 731-743, 1977.

5. Rengasway V: Central neurilemmoma of the jaws: review of the literature and case reuort. Int J Oral Sure 7: 300-304. 1978.

6. Wright BA, Jackson D: Neural tumors of the oral cavity; a review of the spectrum of benign and malignant oral tumors of the oral cavity and jaws. ORAL SURG ORAL MED ORAL PATHOL 49: 509-522, 1980.

7. Sciubba JJ, Sachs SA: Schwannoma of the inferior alveolar nerve in association with the organ of Chievitz. J Oral Path01 9: 16-28, 1980.

8. Zachariades N: Schwannoma of the oral cavity: review of the literature and report of a case. J Oral Med 39: 41-43, 1984.

9. Carstens PHB, Schrodt GR: Malignant transformation of a benign encapsulated neurilemmoma. Am J Clin Path01 51: 144-149, 1969.

10. Schofield IDF, Gardner DG: Central neurilemmoma of the mandible. J Can Dent Assoc 47: 175-177, 1981.

1 I. Satterfield SD, Elzay RP, Mercuri L: Mandibular central schwannoma: report of a case. J Oral Surg 39: 776-777, 1981.

12. Barker BF, Dunlap CL: Intraosseous benign nerve sheath neoplasms of the jaws: a review of the literature and case report, presented to the thirty-third annual meeting of the American Academy of Oral Pathology, San Diego, 1979.

13. Stout AP: Neurofibroma and neurilemmoma. Clin Proc 5: I-12, 1946.

Reprint requests to: Dr. John L. Giunta Tufts University School of Dental Medicine Department of Oral Pathology I Kneeland St. Boston, MA 02111