Which areas are the site of the hallmark palpable purpura in Henoch-Schonlein purpura?

Which areas are the site of the hallmark palpable purpura in Henoch-Schonlein purpura?

• A. Face
• B. Scalp
• C. Palms
• D. Buttocks and lower extremities

Answer: (D)

In Henoch-Schonlein purpura the hallmark skin finding comes from IgA immune complex–mediated inflammation of small dermal vessels (leukocytoclastic vasculitis). This causes leakage of red blood cells into the skin, producing palpable purpura. The characteristic distribution is on gravity-dependent areas, especially the buttocks and lower extremities (legs and thighs). The purpura on these dependent sites reflect where the superficial vessels are most affected by the vasculitic process and by hydrostatic forces, while the face and palms are less commonly involved. So, the typical and most distinctive site for the palpable purpura in this condition is the buttocks and lower extremities.

In Henoch-Schonlein purpura the hallmark skin finding comes from IgA immune complex–mediated inflammation of small dermal vessels (leukocytoclastic vasculitis). This causes leakage of red blood cells into the skin, producing palpable purpura. The characteristic distribution is on gravity-dependent areas, especially the buttocks and lower extremities (legs and thighs). The purpura on these dependent sites reflect where the superficial vessels are most affected by the vasculitic process and by hydrostatic forces, while the face and palms are less commonly involved. So, the typical and most distinctive site for the palpable purpura in this condition is the buttocks and lower extremities.