Differential Diagnosis for Mouth Vesicles in a Teenager

• Single most likely diagnosis
  • Hand, Foot, and Mouth Disease (HFMD): This is a common viral illness in children and teenagers, characterized by the presence of vesicles in the mouth, along with fever and rash on the hands and feet. The justification for this being the most likely diagnosis is its prevalence and the typical presentation that matches the symptoms described.
• Other Likely diagnoses
  • Herpes Simplex Virus (HSV) infection: HSV can cause oral vesicles, particularly in the form of cold sores or primary herpetic gingivostomatitis. This condition is common and can recur, making it a likely consideration.
  • Aphthous ulcers: Although not typically described as vesicles, aphthous ulcers (canker sores) are very common in teenagers and can present with similar symptoms, including pain and oral lesions.
  • Varicella-Zoster Virus (VZV) infection: Reactivation of VZV can cause herpes zoster (shingles), but primary VZV infection (chickenpox) can also present with oral vesicles, especially if the rash is widespread.
• Do Not Miss diagnoses
  • Primary HIV infection: Oral ulcers or vesicles can be a symptom of acute HIV infection. Given the potential long-term consequences of missing this diagnosis, it's crucial to consider, especially if other risk factors are present.
  • Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN): These are severe skin and mucous membrane disorders, usually a reaction to medication or infection. They can present with oral vesicles and are medical emergencies due to their high morbidity and mortality.
• Rare diagnoses
  • Pemphigus Vulgaris: An autoimmune disease that can cause oral vesicles or blisters. It's rare but important to consider due to its potential for significant morbidity if not treated.
  • Behçet's Disease: A form of vasculitis that can cause oral ulcers, among other symptoms. It's rare and more commonly associated with systemic symptoms, but the oral ulcers can sometimes be the initial presentation.
  • Autoimmune disorders like lupus or Crohn's disease can also rarely present with oral lesions, including vesicles, as part of their broader symptomatology.