Differential Diagnosis for Blisters on Lips and Inside the Mouth in an 82-Year-Old Female

Single Most Likely Diagnosis

• Herpes Simplex Virus (HSV) Infection: This is a common cause of oral and lip blisters, especially in older adults. The virus can reactivate due to stress, illness, or other factors, leading to the formation of painful blisters.

Other Likely Diagnoses

• Aphthous Ulcers: Although not typically described as blisters, aphthous ulcers can sometimes present with a blister-like appearance before they ulcerate. They are common in all ages and can be triggered by various factors including stress, certain foods, and minor oral trauma.
• Angular Cheilitis: This condition can cause blister-like lesions at the corners of the mouth, often due to fungal or bacterial infections, and is more common in older adults due to decreased saliva production and other factors.
• Oral Lichen Planus: An autoimmune condition that can cause blister-like lesions inside the mouth, although it more commonly presents with white patches or erosive lesions.

Do Not Miss Diagnoses

• Pemphigus Vulgaris: A rare autoimmune disease that can cause severe blistering of the skin and mucous membranes, including the mouth. It's crucial to diagnose early due to its potential for significant morbidity and mortality.
• Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis: A severe skin and mucous membrane disorder usually caused by an adverse reaction to medication. It can present with blisters and is life-threatening, requiring immediate medical attention.
• Oral Cancer: Although less likely to present initially with blisters, certain types of oral cancer can cause ulcerative or blister-like lesions. Given the patient's age, it's essential not to miss this diagnosis.

Rare Diagnoses

• Bullous Pemphigoid: An autoimmune disease that causes blistering of the skin and, less commonly, the mucous membranes. It's rare but should be considered in the differential diagnosis of blistering lesions.
• Erythema Multiforme: An immune-mediated condition that can cause skin and mucous membrane lesions, including blisters. It's often triggered by infections or medications.
• Primary Herpetic Gingivostomatitis: Although more common in children, this condition can occur in adults, especially if they are immunocompromised, causing widespread oral blisters and ulcers.