Schwannoma (Neurilemoma)

Quick Summary

Clinical Features

Cut surface of a schwannoma shows a thick stalk and a central core of pure white neural tissue,
surrounded by more routine fibrovascular tissue.  Note the traumatic ulcer of the superior 
surface and granulation tissue from trauma in the upper right.






Quick Review for Patients

The schwannoma is a benign tumor of nerve fibers.  It is seldom painful, despite its origin from nerves, because it is actually a proliferation of the nerve sheath or insulation.  It can reach a considerable size, although usually it remains small.  There is no potential for it to become cancer unless the patient has many nerve tumors, i.e. has von Recklinghausen's disease.  Even then the risk is low.  Treatment is conservative surgical removal. 





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Schwannoma (neurilemoma) is a benign neoplasm of the Schwann cells of the neural sheath. At least a fourth, and perhaps as much as half of all cases of neurilemoma and neurofibroma occur in the head and neck region. In some series, one-fourth of the head and neck cases were found in patients with von Recklinghausen neurofibromatosis (neurofibromatosis I).

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Clinical Features

The neurilemoma of the oral region is a slowly enlarging, painless submucosal nodule which is somewhat movable beneath the surface and rarely becomes larger than 2 cm. in greatest diameter. It is most frequently diagnosed in the 25-55 year age group, but can occur at any age; there is no gender predilection. The tongue is the most frequent site of occurrence, perhaps resulting in macroglossia, but any oral site is susceptible. Most lesions are sessile with a normal surface coloration, but occasional lesions will be pedunculated (Figure 1) and larger ones may be lobulated.  Dorsal tongue lesions often show a loss of papillae of the overlying epithelium.

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Pathology and Differential Diagnosis

The neurilemoma is characterized by two basic tissue types. Antoni type A tissue shows fascicles of spindle-shaped Schwann cells streaming around numerous acellular, eosinophilic areas surrounded by paralleled or palisaded spindled cells with blunt, elongated nuclei (Figures 2 & 3). The cells of these Verocay bodies all orient their long axes toward the acellular area, and the areas themselves are oval, linear or serpiginous in shape. A low power microscopic view of this tissue is reminiscent of an aerial view of soldiers aligned against each other across multiple battlefields.

The second tissue type, Antoni type B, lacks the organoid, homogeneous Verocay bodies and consists entirely of less cellular and more randomly arranged spindle cells in a loose, myxomatous stroma (Figures 4 & 5). Neurites usually cannot be demonstrated in either tissue type.

The tumor is typically encapsulated and the associated peripheral nerve may be seen in the microscopic section. Occasional older lesions show degenerative changes consisting of hemorrhage, hemosiderin deposition, mild chronic inflammatory cell infiltration, dense fibrosis, and nuclear pleomorphism. This ancient neurilemoma is benign but must be differentiated from neurofibrosarcoma and malignant neurilemoma.

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Treatment and Prognosis

The neurilemoma is treated by conservative surgical excision, with minimal risk of recurrence.  Malignant transformation in untreated lesions has been reported but is uncommon. Patients with multiple neural tumors should be evaluated for von Recklinghausen neurofibromatosis or MEN III.

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References (Chronologic Order)

Note: General references can be found by clicking on that topic to the left.

Hatziotis JC, Asprides H. Neurilemoma (schwannoma) of the oral cavity. Oral Surg Oral Med Oral Pathol 1967; 24:510-526.

Wright BA, Jackson D. Neural tumors of the oral cavity. Oral Surg Oral Med Oral Pathol 1980; 49:509-522.

Sharma S, Sarkar C, Mathur M, et al. Benign nerve sheath tumors: a light microscopic, electron microscopic and immunohistochemical study of 102 cases. Pathology 1990; 22;191-195.

White W, Shui MH, Rosenblum MK, et al. Cellular schwannoma. A clinicopathologic study of 57 patients and 58 tumors. Cancer 1990; 66:1266-1275.

Colmenero C, Rivers T, Patron M, et al. Maxillofacial malignant peripheral nerve sheath tumours. J Craniomaxillofac Surg 1991; 19:40-46.

Williams HK, et al. Neurilemmoma of the head and neck. Br J Oral Maxillofac Surg 1993; 31:32-35.

Woodruff JM. The pathology and treatment of peripheral nerve tumors and tumor-like conditions. CA Cancer J Clin 1993; 43:290-308.

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SchwannomaGross.jpg (10403 bytes)


Figure 1:  Cut surface of a schwannoma shows a thick stalk and a central core of pure white neural tissue, surrounded by more routine fibrovascular tissue.  Note the traumatic ulcer of the superior surface.  [return to text]

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Figure 2:    [return to text]

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Figure 3: Upper left shows hyaline areas lined by nuclei in a pattern reminiscent of the aerial view of a battlefield.  Lower right area shows streaming lesional cells.  [return to text] 


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