Cysts of oral mucosa have similar historical and clinical features as benign mesenchymal and salivary gland tumors and are often included in the differential diagnosis of these benign tumors. Cysts are typically well-circumscribed, compressible, non-tender, and slowly growing. The overlying mucosa is normal unless traumatized. Location is often helpful in the differential diagnosis of possible soft tissue cysts.
Epidermoid/dermoid cyst* is most commonly seen in the skin and oral mucosa. The most common location in the oral cavity is the floor of the mouth. It is “doughy” to palpation. Treatment is surgical removal and microscopic diagnosis.
Gingival cyst* of the adult is found in the gingiva anterior to the first molars, with a marked predilection for the mandibular canine-premolar region. Simple surgical excision and microscopic diagnosis is the recommended treatment. The prognosis is excellent.
Lymphoepithelial cyst* develops when epithelium entrapped within oral lymphoid tissue undergoes cystic transformation. The typical lymphoepithelial cyst is a small (less than 1 cm), well-circumscribed, yellow or white, soft tissue nodule located in the floor of the mouth or ventral-lateral surface of the tongue. Treatment for lymphoepithelial cyst is excisional biopsy and microscopic diagnosis. There is little tendency for recurrence.
Thyroglossal tract cyst develops from epithelial remnants of the thyroglossal duct that extends from the foramen cecum to the thyroid gland. Cysts can form anywhere along this tract, but most commonly develop in the neck inferior to the hyoid bone. They are non-painful, movable, and fluctuant. Complete surgical excision which removes the cyst, part of the hyoid bone and portions of surrounding muscle, is the recommended treatment. Recurrence is a possibility.