Differential Diagnosis for a 19-year-old Male with Blisters in the Back of the Throat

• Single most likely diagnosis:
  • Herpes Simplex Virus (HSV) infection: This is a common cause of oral and pharyngeal blisters, especially in young adults. The presentation of blisters in the back of the throat is consistent with HSV pharyngitis.
• Other Likely diagnoses:
  • Hand, Foot, and Mouth Disease (HFMD): Caused by Coxsackievirus A, this condition can present with blisters in the mouth and throat, although it's more common in children.
  • Infectious Mononucleosis (Mono): Caused by Epstein-Barr Virus (EBV), mono can lead to pharyngitis and sometimes blister-like lesions in the throat.
  • Streptococcal Pharyngitis: While not typically causing blisters, severe cases can lead to the formation of pus or exudates that might be mistaken for blisters.
• Do Not Miss diagnoses:
  • Diphtheria: A bacterial infection caused by Corynebacterium diphtheriae, which can lead to a severe throat infection with a pseudomembrane that might appear blister-like. Although rare in vaccinated populations, it's critical to consider due to its potential severity.
  • Angina Bullosa Hemorrhagica: A condition characterized by the sudden onset of a single blood blister in the oral cavity, which could potentially occur in the back of the throat.
• Rare diagnoses:
  • Pemphigus Vulgaris: An autoimmune disease that can cause blistering of the mucous membranes, including the throat, though it's more common in older adults.
  • Behçet's Disease: A form of vasculitis that can cause oral and genital ulcers, and potentially throat lesions, though it's rare and usually accompanied by other systemic symptoms.
  • Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis: Severe skin and mucous membrane disorders usually caused by medications or infections, which could potentially involve the throat.