A mildly ill 4-year-old presents with exudative pharyngitis and erythematous nonblanching lesions on the legs. Rapid strep test is positive. What is the most likely diagnosis?

A mildly ill 4-year-old presents with exudative pharyngitis and erythematous nonblanching lesions on the legs. Rapid strep test is positive. What is the most likely diagnosis?

• A. Scarlet fever
• B. Systemic lupus erythematosus
• C. Henoch-Schonlein purpura
• D. Immune thrombocytopenia purpura

Answer: (C)

Nonblanching, palpable purpura in a child points to a small-vessel vasculitis, most classically IgA-mediated Henoch-Schönlein purpura. HSP typically follows a URI and presents with the triad of palpable purpura on the buttocks and legs, abdominal pain, and arthritis, with possible kidney involvement such as hematuria or proteinuria. A positive rapid strep test can reflect a concurrent strep pharyngitis and doesn’t explain the purpuric rash. Scarlet fever would cause a diffuse blanching red rash with a sandpaper texture, not nonblanching purpura, so it’s less likely here. Management is supportive, focusing on hydration and pain control, with monitoring for abdominal symptoms and renal involvement (urinalysis).

Nonblanching, palpable purpura in a child points to a small-vessel vasculitis, most classically IgA-mediated Henoch-Schönlein purpura. HSP typically follows a URI and presents with the triad of palpable purpura on the buttocks and legs, abdominal pain, and arthritis, with possible kidney involvement such as hematuria or proteinuria. A positive rapid strep test can reflect a concurrent strep pharyngitis and doesn’t explain the purpuric rash. Scarlet fever would cause a diffuse blanching red rash with a sandpaper texture, not nonblanching purpura, so it’s less likely here. Management is supportive, focusing on hydration and pain control, with monitoring for abdominal symptoms and renal involvement (urinalysis).