Background
Erythema multiform (EM) is an acute, immune-mediated disorder, that affects the skin and mucous membranes. The major form (EM major, EMM) is a more severe, rare, potentially life-threatening disorder.

Case Presentation Summary
A 25-month-old healthy boy presented with an acute rash with erythematous papules, initially diagnosed as varicella. There was no recent immunization or any drug. He developed conjunctival hyperemia, mucosal involvement, fever, great discomfort and poor oral and fluid intake, leading to the suspected diagnosis of Stevens-Johnson Syndrome and referral to our hospital. At admission, the patient showed target-like lesions on his extremities with centripetal distribution affecting a body surface area of twenty-five percent, bullae with negative nikolsky sign and oral mucosa ulcers, with no other significant findings on physical examination. Laboratory tests showed leukocytosis and increased C-reactive protein without other abnormalities. After observation by Dermatology, the diagnosis of EMM was proposed. The boy was hospitalized with supportive care, methylprednisolone, ceftriaxone, azithromycin and acyclovir. Exams showed doubt Ig M for HSV-1, negative Ig G and positive viral load; serologies were negative for VZV,  HHV-6/7, HSV-2, CMV, EBV, Chlamydia pneumonia and Mycoplasma pneumonia. Skin lesions resolved within two weeks leaving hyperpigmented areas at discharge.

Learning Points/Discussion
With this case report, the authors highlight the difficulty in diagnosis of some cases without classical presentation and where no obvious trigger is found. It is important to recognize EMM in order to avoid patient misdiagnosis and mismanagement.

CHICKENPOX, STEVENS-JOHNSON OR… WHAT ELSE?