Adult Hand, Foot, and Mouth Disease

A previously healthy 22-year-old Japanese man presented with fever, sore throat, bilateral conjunctival congestion, and a skin rash, which he had been experiencing for 4 days before hospital admission. Two days before admission, he tested negative for Group A Streptococcus by rapid antigen testing and for SARS-CoV-2 by antigen testing. On the same day, he noticed a non-pruritic rash on both palms and soles. Despite taking non-steroidal anti-inflammatory drugs, he continued to have a high-grade fever and a sore throat caused by oral ulcers, prompting hospital admission due to inability to maintain adequate hydration.