Henoch-Schönlein Purpura Nephritis: Diagnosis, Clinical Features, and Differential Considerations

Henoch-Schönlein Purpura (HSP) nephritis is a systemic vasculitis that primarily affects small blood vessels and often leads to renal involvement. It is most commonly seen in children but can also occur in adults. Early and accurate diagnosis is crucial for effective management and long-term prognosis.

Key Diagnostic Criteria for HSP Nephritis

Skin Manifestations: One of the hallmark signs of HSP nephritis is palpable purpura—typically appearing symmetrically on the lower extremities or all four limbs. These skin lesions do not blanch under pressure and are caused by inflammation of the capillaries. Importantly, patients usually maintain normal platelet counts, which helps differentiate HSP from other bleeding disorders.

In addition to skin symptoms, many patients experience gastrointestinal involvement, such as abdominal pain, nausea, vomiting, or even gastrointestinal bleeding. Joint manifestations, including arthralgia or arthritis—especially in the knees and ankles—are also frequently observed during the acute phase of the disease.

Renal Involvement and Urinary Abnormalities

Renal complications typically emerge during the course of the illness or shortly after the resolution of skin purpura. The presence of hematuria—either gross (visible) or microscopic—is a common indicator of kidney involvement. Additionally, proteinuria and the detection of urinary casts further support the diagnosis of HSP-related glomerulonephritis.

The onset of these urinary abnormalities signals immune complex deposition in the glomeruli, leading to inflammation and impaired kidney function. Regular urinalysis and monitoring of renal function are essential for early detection and intervention.

Pathological Characteristics and Comparison with IgA Nephropathy

Histologically, HSP nephritis closely resembles IgA nephropathy, as both conditions show dominant IgA immune complex deposits in the mesangial areas of the glomeruli. However, HSP nephritis often presents with more severe histopathological changes, including greater degrees of capillary loop necrosis and fibrous deposition within the glomerular tufts.

Renal biopsy plays a critical role in confirming the diagnosis and assessing the extent of damage. Pathologists classify the severity using standardized scoring systems, which guide treatment decisions and help predict long-term outcomes.

Differential Diagnosis: Conditions to Rule Out

Due to overlapping clinical features, several other systemic conditions must be excluded when diagnosing HSP nephritis. These include:

• ANCA-associated vasculitis (small vessel vasculitis): Presents with similar renal and skin findings but typically shows positive ANCA antibodies and different immunofluorescence patterns.
• Antiphospholipid antibody syndrome: Associated with thrombotic events and specific autoantibodies, not immune complex-mediated vasculitis.
• Sepsis-induced purpura: Often accompanied by fever, leukocytosis, and hemodynamic instability, distinguishing it from the more indolent course of HSP.
• Allergic vasculitis (hypersensitivity vasculitis): Triggered by drugs or infections but lacks the classic triad of skin, joint, and GI symptoms seen in HSP.
• Systemic Lupus Erythematosus (SLE): Can mimic HSP with rash and nephritis, but SLE patients usually have positive ANA, anti-dsDNA antibodies, and multi-organ involvement.

A thorough laboratory workup—including autoimmune panels, infection screening, and complement levels—is essential to rule out these mimics.

Treatment Response and Recovery Criteria

Remission and recovery in HSP nephritis are defined by the complete resolution of clinical symptoms, including the absence of hematuria and proteinuria. To confirm sustained remission, patients should remain symptom-free for at least six consecutive months without relapse.

Long-term follow-up is recommended, especially in cases with moderate to severe renal involvement, as some individuals may develop chronic kidney disease years after the initial episode. Blood pressure control, urine monitoring, and lifestyle modifications play key roles in preventing progression.

With timely diagnosis, appropriate immunosuppressive therapy when needed, and careful monitoring, most patients—particularly children—achieve favorable outcomes. However, awareness of potential complications and adherence to follow-up protocols remain vital for optimal care.