What is the diagnosis and treatment for a patient presenting with abdominal pain and purpuric rashes on the legs?

Henoch-Schönlein Purpura (IgA Vasculitis)

The combination of abdominal pain and purpuric rashes on the legs is classic for Henoch-Schönlein Purpura (HSP), also known as IgA vasculitis, which presents with the characteristic triad of palpable purpura on lower extremities, abdominal pain, and arthritis. 1, 2

Clinical Diagnosis

The diagnosis is primarily clinical, based on the characteristic presentation:

• Palpable purpuric rash on lower extremities and buttocks is the hallmark finding—this is non-thrombocytopenic purpura that does not blanch 1, 2
• Abdominal pain occurs in the majority of patients and can range from mild colicky pain to severe pain with gastrointestinal bleeding 3, 1
• Joint involvement with arthralgia or arthritis, typically affecting knees and ankles 1
• Renal involvement with hematuria or proteinuria may develop 1, 4

Confirmatory Testing

• Skin biopsy showing leukocytoclastic vasculitis with IgA deposits in vessel walls on direct immunofluorescence is diagnostic 2, 4
• Laboratory workup should include complete blood count, comprehensive metabolic panel, urinalysis, and renal function tests to assess for complications 5
• Beta-hCG must be obtained in all women of reproductive age before proceeding with imaging 5, 6

Treatment Approach

Mild to Moderate Disease

Supportive care is the mainstay for uncomplicated HSP:

• Adequate hydration and pain control 2
• Close monitoring for development of complications, particularly gastrointestinal bleeding and renal involvement 3, 4

Severe Disease Requiring Systemic Corticosteroids

Systemic corticosteroids (prednisolone) should be initiated for:

• Severe abdominal pain 3, 7
• Gastrointestinal bleeding 3
• Hemorrhagic bullous lesions 2
• Renal involvement with significant proteinuria 4

The typical regimen involves prednisolone tapered over 4-5 weeks, though the optimal duration remains controversial 2. Early corticosteroid use may reduce the extent of lesions and minimize sequelae, though up to 25% of patients may still develop hyperpigmentation or scarring 2.

Refractory Disease

For steroid-resistant cases:

• Leukocytapheresis has shown efficacy in severe, refractory HSP with complete resolution of symptoms after 3 treatments 7
• Intensive immunosuppressive therapy and plasma exchange may be considered for life-threatening complications 4

Critical Complications Requiring Urgent Intervention

Life-Threatening Gastrointestinal Involvement

Severe gastrointestinal bleeding or bowel infarction requires immediate surgical evaluation:

• Fulminant bleeding with hemoglobin drop >7 g/dL necessitates urgent endoscopy, mesenteric angiography, and potential surgical resection 3
• Paralytic ileus or signs of bowel infarction (severe persistent pain, peritoneal signs) require emergency laparotomy, as intestinal infarction from necrotizing vasculitis can be fatal despite aggressive treatment 4
• CT abdomen/pelvis with IV contrast should be obtained if surgical abdomen is suspected 6

Monitoring for Renal Complications

• Serial urinalysis and renal function tests are essential, as renal involvement can progress to chronic kidney disease 1, 4

Common Pitfalls to Avoid

• Do not delay treatment while awaiting skin biopsy results if clinical presentation is classic—HSP is a clinical diagnosis and biopsy is confirmatory 1, 2
• Do not assume mild abdominal pain will remain benign—gastrointestinal complications can rapidly progress to life-threatening bleeding or infarction 3, 4
• In adults, HSP can have a more severe course with higher risk of intestinal infarction compared to pediatric cases 4
• Failing to monitor for renal involvement can result in missed progression to chronic kidney disease 1, 4

Differential Considerations

While HSP is the most likely diagnosis, other conditions to consider include:

• Rocky Mountain Spotted Fever presents with fever, headache, and petechial purpuric rash, but typically involves palms and soles rather than just lower extremities 8
• Meningococcemia can cause purpura fulminans but presents with acute sepsis and rapid deterioration 8
• Adult-onset Still's disease may have a vasculitic purpuric rash but typically presents with high spiking fevers and an evanescent salmon-pink rash rather than purpura 8