Henoch-Schönlein purpura (HSP)

 Henoch-Schönlein purpura (HSP) is an immunoglobin A (IgA)-mediated systematic vasculitis affecting the vasculature of several systems including the gastrointestinal tract, renal system, skin, and joints. 

It is characterized by the presence of a vasculitic purpuric rash, abdominal pain, joint pain, renal injury, pulmonary inflammation, or central nervous system involvement . 

Around 90% of cases occur in children under the age of 10, with a greater preponderance for males .

Although self-limiting in nature, complications such as gastrointestinal hemorrhage and end-stage renal failure may occur .

Immunoglobin A nephritis affects 60% of patients and can vary in severity from the presence of asymptomatic microscopic haematuria with proteinuria to irreversible renal failure requiring renal transplantation.

 Diagnosis of HSP follows the criteria set by the European League Against Rheumatism (EULAR), Paediatric Rheumatology International Trial Organisation (PRINTO), and Paediatric Rheumatology European Society (PRES).

 These diagnostic criteria include the necessary presence of a palpable purpuric rash with lower limb predominance, no thrombocytopenia or coagulopathy, and at least one of the following: 

1)acute abdominal pain, 

2)acute arthritis, or arthralgia, 

3)kidney involvement, or 

4)biopsy showing leukocytoclastic vasculitis.

Examination plays a key role in diagnosing HSP and there are several common findings.

 Dermatological manifestations involve a symmetrical non-tender pruritic erythematous, macular, or urticarial rash, which develops into palpable purpura with blanching papules.

 The distribution of this rash varies depending on the age of the patient. Children under one-year-old develop a widespread rash involving the face, torso, and upper extremities, whilst in toddlers the rash typically involves the lower back and buttocks. In older children and adults, the rash is usually isolated to the lower limbs and buttocks.

Arthritis and joint pains are more commonly featured in older children and adults. In addition, adult-onset HSP is more likely to present with arthralgia without arthritis.

Renal involvement is one of the main indicators of morbidity from HSP. Around 30% to 50% present with haematuria and or proteinuria within six weeks and the likelihood of developing renal pathology increases with the age of onset . This is usually self-limiting.

Although HSP is a clinical diagnosis, laboratory studies and imaging may help in more atypical cases. As well as routine laboratory studies, an extensive immune panel of blood may be required to support the diagnosis and rule out alternate pathophysiology, including ANA, ANCA, RF, and factors VIII and XIII levels. Imaging can also be considered, such as renal or skin biopsy, which may play a role when the diagnosis is uncertain or in monitoring for possible complications and system involvement.

The management of HSP is largely supportive and involves a combination of analgesia, anti-emetics, hydration, and monitoring for complications. Treatments aim to provide acute symptom relief and prevent renal deterioration. Cutaneous involvement does not usually require management . As HSP is characterized by IgA deposition and white cell infiltration within blood vessel walls, corticosteroids can play a role in inhibiting this inflammatory process.

Henoch-Schönlein purpura is usually self-limiting. Most patients completely recover with symptom resolution within eight to 10 weeks of onset and 5% develop chronic symptoms .Complete clinical resolution is more likely in patients with mild renal involvement, no neurological complications. Disease may recur in some patients but it is usually self limiting.

Long-term follow-up studies have shown delayed-onset chronic kidney disease as a complication in cases where steroids were used in management.

This emphasizes the importance of early diagnosis and management.

References

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