Differential Diagnosis for Redness Line Under Lower Lip

• Single Most Likely Diagnosis
  • Angular cheilitis: This condition is characterized by inflammation of the corners of the mouth, which can sometimes present as a red line under the lower lip. It is often caused by fungal or bacterial infections and can be exacerbated by factors such as dry mouth, vitamin deficiencies, or ill-fitting dentures.
• Other Likely Diagnoses
  • Contact dermatitis: This is a type of skin inflammation caused by contact with irritants or allergens. If the skin under the lower lip comes into contact with something that causes an allergic reaction or irritation, it could lead to redness and a line-like appearance.
  • Irritation from oral habits: Habits such as licking the lips or the area under the lower lip can cause irritation and redness due to the constant moisture and potential for saliva to irritate the skin.
  • Lip biting or chewing: Some people have a habit of biting or chewing on the inside of their lip or the skin under their lip, which can cause redness and irritation.
• Do Not Miss Diagnoses
  • Oral cancer: Although less common, a red line or lesion under the lower lip could be an early sign of oral cancer, particularly if it persists, grows, or is accompanied by other symptoms such as difficulty swallowing or a lump in the neck.
  • Lupus: Systemic lupus erythematosus (SLE) can cause a variety of skin manifestations, including redness and lesions in the mouth and on the lips. It's crucial to consider this diagnosis, especially if other systemic symptoms are present.
• Rare Diagnoses
  • Lichen planus: This is a rare condition that can affect the skin and mucous membranes, leading to red, inflamed lesions. While it more commonly affects the inside of the mouth, it could potentially cause symptoms under the lower lip.
  • Sarcoidosis: A condition that can cause inflammation in various parts of the body, including the skin. It might present with lesions or redness in unusual locations, including under the lower lip, though this would be uncommon.