Mucous gland cysts are the most common small salivary adenoma-like lesions that occur on the lower lip and ventral aspect of the tongue. Its etiology is often due to injury of the submucosal glands by friction of the tongue body movement by the lower anterior teeth and by conscious or unconscious biting of the lower lip. The clinical manifestations are: the cyst is located in the submucosa and the surface is covered with only a thin layer of mucosa, so it is translucent and light blue vesicles. The cyst is easily ruptured by the bite, and the egg-white clear mucous fluid flows out, and the cyst disappears. After the rupture heals, it is filled with mucus again and the cyst is formed again. Repeated ruptures no longer have the clinical features of cysts, but show thicker white scar-like protrusions and reduced transparency of cysts. Treatment modality: The most common treatment modality is surgical excision.