Choice A. Erythema infectiosum is caused by parvovirus B19 and causes a classic "slapped cheek", not sandpaper, rash.
Choice B. Hand, foot, and mouth disease is a common Coxsackie virus infection that presents in young children with lesions on the hands/feet and oral ulcerations, findings not present in this patient.
Choice C. Diagnosis of Kawasaki disease (KD) requires 5 days of fever and ≥4 clinical criteria: >1.5 cm cervical node, polymorphous rash, edema of the hands/feet, conjunctivitis, and mucosal changes (eg, strawberry tongue, dry/cracked lips). KD is unlikely in this patient with only 2 days of fever and 2 of the listed criteria.
Choice D. Mononucleosis can present with exudative pharyngitis and a rash; however, posterior cervical lymphadenopathy is typical.
Choice E. Roseola presents with high fever followed by a morbilliform rash that typically erupts once the patient has defervesced. In contrast, this patient with a rash still has fever, making roseola unlikely.
Explanation
Sandpaper texture
Strawberry tongue
Circumoral pallor
Educational objective: Scarlet fever is caused by group A Streptococcus (S. pyogenes) and presents with fever, pharyngitis, circumoral pallor, strawberry tongue, and rash. The classic "sandpaper" rash is prominent along skin folds (eg, axillae, groin) and often results in desquamation.
Choice G. Staphylococcal scalded skin is caused by exfoliative strains of Staphylococcus aureus and presents with superficial flaccid bullae followed by extensive exfoliation of the skin. It is most common in infancy and rarely occurs beyond age 5.
