Writing the Final Diagnosis of Henoch-Schönlein Purpura
The final diagnosis of Henoch-Schönlein purpura should be written as "IgA vasculitis (Henoch-Schönlein purpura)" with specification of the pattern of organ involvement, including the presence or absence of nephritis, and supported by histopathological confirmation showing IgA-dominant immune complex deposition in affected tissues. 1, 2
Diagnostic Format Structure
Primary Diagnosis Statement
- Write the primary diagnosis as: "IgA vasculitis (Henoch-Schönlein purpura)" or simply "Henoch-Schönlein purpura" 3, 2
- This reflects the current understanding that HSP is fundamentally an IgA-mediated small vessel vasculitis 3, 4
Pattern of Organ Involvement
Document the specific organ systems affected, following a systematic approach similar to glomerulonephritis diagnostic reporting 1:
- Cutaneous involvement: Specify presence of palpable purpura, typically on lower extremities and buttocks 1, 5
- Renal involvement: If present, specify as "HSP with nephritis" or "IgA vasculitis with glomerulonephritis" 3, 2
- Gastrointestinal involvement: Document presence of abdominal pain, bleeding, or other GI manifestations 4, 5
- Joint involvement: Note arthralgia or arthritis if present 5, 6
- Other organ systems: Include any pulmonary, cardiac, neurological, or genitourinary complications if present 3, 4
Histopathological Confirmation
The diagnosis should include reference to biopsy findings when available 1, 2:
- For skin biopsy: "Leukocytoclastic vasculitis with IgA-dominant immune complex deposition" 2
- For renal biopsy (if nephritis present): "Mesangial proliferative glomerulonephritis with IgA-dominant deposits" following the format used for IgA nephropathy 1
Clinical Modifiers
Add clinical context that affects prognosis or management 1:
- Age of patient (pediatric vs. adult, as adults have more severe disease) 3, 4
- Severity of renal involvement (if present): mild hematuria vs. nephrotic-nephritic syndrome 2
- Presence of crescentic glomerulonephritis (indicates severe disease requiring potential immunosuppression) 7
Example Diagnostic Statements
Complete Format (with renal involvement):
Primary diagnosis: IgA vasculitis (Henoch-Schönlein purpura) with nephritis 1, 2
Pattern of involvement: Cutaneous purpura, arthralgia, and mesangial proliferative glomerulonephritis 1
Histopathology: Skin biopsy showing leukocytoclastic vasculitis with IgA-dominant immune deposits; renal biopsy showing mesangial proliferative glomerulonephritis with IgA deposits 1, 2
Additional features: Adult presentation with nephrotic-range proteinuria 3, 4
Simplified Format (without renal involvement):
Primary diagnosis: IgA vasculitis (Henoch-Schönlein purpura) 2
Clinical features: Palpable purpura of lower extremities, arthralgia, abdominal pain 5
Histopathology: Skin biopsy confirming leukocytoclastic vasculitis with IgA deposits 2
Critical Diagnostic Considerations
Importance of Tissue Confirmation
- Skin biopsy with immunofluorescence is essential for definitive diagnosis, as IgA deposits in vessel walls are sine qua non for HSP diagnosis 2
- Clinical diagnosis alone can lead to missed diagnoses or overdiagnosis, resulting in inappropriate follow-up or missed chronic renal failure 2
- Renal biopsy is indicated when diagnosis is uncertain, atypical presentation occurs, or when there is severe nephritis 7, 2
Common Diagnostic Pitfalls
- Avoid diagnosing HSP based solely on clinical criteria without histopathological confirmation, as other leukocytoclastic vasculitides can mimic HSP 2, 6
- Do not overlook delayed renal manifestations—nephritis can appear years after initial presentation 2
- Remember that incomplete clinical pictures are common; not all patients present with the classic tetrad of purpura, arthritis, abdominal pain, and nephritis 5, 6
Differential Diagnosis Exclusion
Document that other causes have been excluded 7: