A Mysterious Case of Bumps on the Beach

October 2, 2017

After a few days at play on the beach, young brothers present with similar erythematous eruptions on their abdomens. Can you Dx?

Two young boys have been enjoying time at the beach; both end up with erythematous papular lesions on their abdomens that cut off abruptly at the waistline. After a brief history, the diagnosis seems fairly certain. What's in your differential?