The inner wall of the oral cavity generally refers to the oral lip mucosa and buccal mucosa, the appearance of a lot of yellow rice-like tissue is generally seborrhea, also known as sebaceous gland ectasia, as follows. 1. Sebaceous ectasia is the ectopic, misplaced sebaceous glands, commonly found in the lip and buccal mucosa. It is characterized by yellowish or yellowish-white patches or papules that are scattered or clustered in clusters and are the size of a grain of corn. Its surface is smooth and soft, generally no conscious symptoms. 2. Histopathologic examination shows that mature normal sebaceous glands are located in the lamina propria of the epithelium, and the sebaceous ducts extend to the mucosal surface. Oral lip mucosa or buccal mucosa yellow rice-like tissue may have other causes, it is recommended to go to the hospital in a timely manner, clear cause for targeted treatment.