Differential Diagnosis for Hand, Foot, and Mouth Disease (HFMD) in Adults

Single Most Likely Diagnosis

• Enteroviral Infection (Coxsackievirus A or Enterovirus 71): This is the most common cause of HFMD, characterized by fever, oral ulcers, and a rash on the hands and feet. Adults can be infected, especially if they are in close contact with infected children.

Other Likely Diagnoses

• Herpangina: Caused by Coxsackieviruses, this condition presents with fever and oral ulcers, similar to HFMD, but typically without the rash on the hands and feet.
• Aphthous Stomatitis: Commonly known as canker sores, these are painful ulcers in the mouth that can be mistaken for the oral lesions of HFMD.
• Erythema Multiforme: An immune-mediated condition that can cause skin lesions and oral ulcers, which might be confused with HFMD.

Do Not Miss Diagnoses

• Herpes Simplex Virus (HSV) Infection: While less common, HSV can cause severe oral and genital lesions, and its diagnosis is crucial due to the availability of specific antiviral treatments.
• Varicella-Zoster Virus (VZV) Infection: Reactivation of VZV can cause herpes zoster (shingles), which, although typically presents with a dermatomal rash, can be confused with HFMD in its early stages.
• Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis: These are severe skin and mucous membrane disorders, usually drug-induced, which can present with oral ulcers and skin lesions, and are medical emergencies.

Rare Diagnoses

• Kawasaki Disease: Although predominantly seen in children, Kawasaki disease can rarely occur in adults and presents with fever, rash, oral changes, and lymphadenopathy, which might be confused with HFMD.
• Pemphigus Vulgaris: An autoimmune disease causing blistering of the skin and mucous membranes, which can be mistaken for the oral and skin lesions of HFMD.
• Parvovirus B19 Infection: Known for causing the "slapped cheek" syndrome in children, it can also cause a rash and fever in adults, potentially mimicking HFMD.