What Are Granular Cell Tumors?
A granular cell tumor (GCT) is a soft tissue neoplasm (an abnormal mass of tissues) first reported in 1926 by Abrikossoff. This was considered for a long time to be a tumor derived from myoblastic origins and was earlier called granular cell myoblastoma. However, recent research over the last decade indicates the origin of the lesion is to be from Schwann cells (the primary cells of the nervous system that surround neurons, keeping them alive and covering them with a myelin sheath).
What Are Granular Cell Tumors of the Oral Cavity?
Granular cell tumors (GCT) of the oral cavity are mostly benign (non-cancerous). However, it is also true that up to two percent of the GCTs tend to be malignant (cancerous). On the other hand, these lesions rarely have the potential for distant or local metastasis (spread to other parts of the body). Moreover, various types of research found that granular cell tumors are derived from neoplastic processes and neural derivatives. These tumors, on histopathologic examination, show the collection of plump cells with abundant granular cytoplasm hence the name for the lesion.
These tumors are usually limited to specific areas of the oral cavity, with the tongue being the most common location. These tumors can also occur anywhere in the body, not just in the oral cavity.
What Is the Epidemiology of Oral Granular Cell Tumors?
The estimated incidence of oral granular cell tumors globally is low, with an incidence of approximately 1: 1.000,000 yearly. Moreover, it does not have any geographical variations or racial afflictions. The gender preference suggests slightly more occurrences in females than males. These lesions most frequently occur around the fourth to sixth decade of life, and are infrequent in children.
What Are the Clinical Features of Oral Granular Cell Tumors?
The clinical manifestations of oral granular cell tumor include -
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The oral granular cell tumors are clinically asymptomatic solitary lesions primarily present on the anterior tongue region with a nodular consistency.
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They are primarily yellowish or pinkish.
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They are very slow growing and painless.
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If the lesions are multiple in the tongue, they can appear on the dorsal surface of the tongue.
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Other than the tongue, the possible regions where the tumor lesions can occur (rarely) are the floor of the mouth, the upper lip, the commissures of the lip, and the lower lip.
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The yellowish, firm, and nodular lesions on the tongue are specific characteristics that help determine this lesion by being investigated through a biopsy.
How Is Oral Granular Cell Tumor Diagnosed?
Healthcare professionals recommend an excisional biopsy of the lesion to give a clear picture upon histopathological examination.
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Histopathologically, the tumor cells appear as well-encapsulated or thickly encapsulated.
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The lesional cells appear as a polygonal shape, demonstrating numerous cytoplasmic granules with the cell cytoplasm staining positive specifically for the S-100 protein (immunohistochemical staining method for neural tumors).
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The absence of nuclear or cellular pleomorphism (variation in shape or size) is another characteristic histopathologic feature. Very rarely, the abnormal mitotic activity would be observed in these lesions, making this an atypical pathologic condition, unlike other cancer or tumor lesions with cells with increased mitotic activity.
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Another well-known phenomenon observed histopathologically in GCT lesions is the pseudoepitheliomatous hyperplasia feature (PEH) in the overlying or superficial epithelium. Upon excisional biopsy, PEH lesions must always be differentially diagnosed from oral squamous cell carcinomas to confirm the final diagnosis. Otherwise, these lesions would be misdiagnosed as squamous cell carcinomas of the oral cavity or tongue.
What Is the Treatment of Granular Cell Tumors?
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The treatment for these lesions consists of conservative excision with preservation of anatomic structure and oral function based on the location and extent of the lesion in the oral cavity. Recurrence of the lesion is rare, and radiotherapy is advised in case of large tumors or recurring lesions.
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Chemotherapy has not been indicated in the treatment of GCT, and the prognosis post-surgical resection is excellent for these individuals.
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Patients should be instructed upon proper oral hygiene measures, regular dental check-ups, and systemic health care.
Conclusion
Granular cell tumors tend to be primarily benign though they may also have a malignant potential. Moreover, oral granular cell tumors tend to occur on the surface of the tongue and rarely in other parts of the oral cavity. Conservative surgical approach is often employed for removing oral granular cell tumors. These lesions, with timely management, have an excellent prognosis and are not usually associated with high recurrence rates in the oral cavity.
