Henoch-Schonlein Purpura

Epidemiology and Etiology:

· 3-8 years most commonly

· Strong background of atopy in 1/3^rd

· Post-URTI often

Common sites:

· Skin

· Extensor surfaces of arms and legs

· buttocks

· Kidneys (1/3^rd)

· GI tract

Gross features:

· Purpuric skin lesions

Histologic features:

· Kidney:

· Varying severity:

· mild focal mesangial proliferation

· diffuse mesangial proliferation

· crescentic glomerulonephritis

· vasculitis is rare

· skin

· subepidermal hemorrhages

· necrotizing vasculitis involving small vessels of the dermis

· GI:

· Vasculitis maybe

Immunophenotype:

Marker:	Sensitivity:	Specificity:
IgA (on frozen tissue)
IgG (on frozen tissue)	Some
C3 (on frozen tissue)	Some

· IgA deposited in the glomerular mesangium (similar to IgA nephropathy)

· IgA deposited in small vessels of dermis

Molecular features:

·

Other features:

· Abdominal pain, vomiting, intestinal bleeding

· Nonmigratory arthralgias

· Hematuria, proteinuria, nephritic syndrome

· Rapidly progressive glomerulonephritis in a minority

References:

· Kumar V, Fausto N, Abbas A. Robbins & Cotran Pathologic Basis of Disease, Seventh Edition. 7th ed. Saunders; 2004:1552.