Henoch–Schönlein purpura

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16.7 Henoch–Schönlein purpura

Karen McCarthy

Essentials

1 There is no diagnostic laboratory test for the diagnosis of Henoch-Schönlein purpura.
2 The diagnosis is clinical and consists of the tetrad: palpable purpura in patients with neither thrombocytopenia or coagulopathy, arthritis/arthralgia, abdominal pain and renal disease.
3 Urinalysis, and blood pressure should be measured at presentation.
4 Clinical hallmark of Henoch–Schönlein nephritis is haematuria.
5 Onset of nephritis may be delayed for weeks or months after onset of other symptoms.
6 All patients with Henoch–Schönlein nephritis need follow up for 6 months even if urinalysis is normal at presentation.
7 There is no need for follow up beyond the first 6 months if urinalysis remains normal.
8 Recurrence of Henoch–Schönlein purpura is common and is normally observed within 4 months of resolution of original symptoms.

Introduction

Henoch–Schönlein purpura (HSP) is the most common acute vasculitis affecting children. It has a prominent cutaneous component. It is a leukocytoclastic vasculitis that affects small vessels (arterioles and venules). The aetiology is unknown. The disease is more common in males, with mean age of occurrence 4–7 years. Infants tend to have milder disease and those less than 2 years of age are less likely to have nephritis and abdominal pain in comparison with older children. With the exception of nephritis, it is generally an acute self-limited illness lasting from several days to several weeks.

The characteristic histological finding on skin biopsy is neutrophil infiltration in and around dermal vessels. Histological changes in the kidney range from minimal change to focal or diffuse mesangial proliferation that may be accompanied by glomerular crescent formation. The characteristic finding on immunofluorescence is diffuse mesangial deposition of immunoglobulin A (IgA) and complement 3 (C3). IgA plays a central role in the pathogenesis of HSP.

The reported incidence of nephritis is 20-50% but may in fact be higher. Renal involvement may manifest with haematuria ± proteinuria and occasionally with nephritic or nephrotic syndrome or with renal failure associated with rapidly progressive glomerulonephritis. Risk factors for renal progression are nephrosis, hypertension, renal impairment at presentation, and haematuria.

History

There is usually a history of antecedent upper respiratory tract infection. The characteristic rash is the most frequent presentation. Arthritis is the second most frequent manifestation, occurring in approximately 80% and though it may be incapacitating, it is self-limiting and non-deforming. Gastrointestinal involvement occurs in 50–75% of patients and is potentially the most serious complication of HSP due to the possible development of gastrointestinal bleeding and intussusception.

The clinical hallmark of HSP nephritis is haematuria. In contrast to arthritis and abdominal pain, it is extremely uncommon for nephritis to precede the appearance of the rash. The onset of nephritis may in fact be delayed for weeks or months after the onset of other symptoms. Approximately 80% of patients manifest nephritis within 4 weeks and 95% within 3 months of the onset of other symptoms.

Examination

The clinical features of HSP may be atypical in the extremes of age. The clinical manifestations can develop over days or weeks. The characteristic rash consists of crops of palpable purpura and is symmetric in distribution and located on the extensor surfaces of the arms, legs and buttocks. It is worth noting that the rash is not restricted to these areas. The rash may begin with urticaria that progresses over 24 hours to palpable purpura. The arthritis involves the knees, ankles or feet and may result in refusal to weight bear. Periarticular swelling and tenderness are often noted.

Gastrointestinal symptoms of nausea, vomiting and abdominal pain occur in approximately 50%. These symptoms are caused by submucosal haemorrhage and oedema. Asymptomatic microscopic haematuria occurs in most but up to 40% have gross haematuria. Proteinuria occurs in conjunction with haematuria in two-thirds of patients but the occurrence of proteinuria alone is rare.

Investigations

• Diagnosis of HSP is straightforward when the typical rash is present.
• Diagnosis of HSP requires a normal platelet count by definition.
• There is no diagnostic laboratory test for HSP – routine laboratory tests are neither specific nor diagnostic.
• Urinalysis should be performed to establish the presence of microscopic haematuria, with or without proteinuria.
• Serum creatinine should be checked when HSP nephritis is present.
• Blood pressure should be measured and recorded at presentation for baseline evaluation.

Differential diagnosis

The differential diagnosis of a purpuric rash is broad. Purpura may be the initial manifestation of an infectious process.

Meningococcaemia

Palpable purpura (as opposed to the usual non-palpable purpura) can occur if there are pre-existing coagulation abnormalities (such as protein S or protein C deficiency). This diagnosis must be considered in any child with purpura.

Kawasaki disease

Considered in the patient with an unremitting fever with a maculopapular rash that is prominent on the lower extremities. This rash, however, does not appear in crops and is not associated with arthritis. The eye findings in Kawasaki disease are usually absent in HSP.

Bacterial endocarditis, infectious mononucleosis, rubeola and streptococcal infection may present with a purpuric rash. HSP can occur with other forms of vasculitis or autoimmune disease, such as inflammatory bowel disease or familial Mediterranean fever.

Rocky Mountain spotted fever should be considered in endemic areas when there is a history of tick exposure.

Treatment

Treatment is mainly supportive with hydration, rest and analgesics.

There is suggestive evidence that corticosteroids enhance the rate of resolution of the arthritis and abdominal pain but do not appear to prevent recurrence of disease. Available data, though considered somewhat controversial, suggest that patients with severe nephritis (haematuria, nephrotic syndrome, decreased glomerular filtration rate (GFR) and crescent formation involving >50% of the glomeruli) should receive a combination of high-dose intravenous methylprednisolone (30 mg kg–1 day–1) for 3 days followed by oral steroids plus an immunosuppressive agent, either azathioprine or cyclophosphamide.

Plasmapheresis has been reported to be of benefit in a few patients with rapidly progressive HSP glomerulonephritis i.e. severe disease.

Hypertension – angiotensin blockade by use of angiotensin-converting enzyme (ACE) inhibitors like enalapril may decrease proteinuria and result in slower deterioration in renal function as well as providing effective control of blood pressure.

Disposition

Outpatient management is appropriate for most patients with HSP.

Inpatient management may be required for management of abdominal pain and the arthritis/arthralgia, especially if the child is unable to ambulate. Urinalysis should be performed weekly whilst the disease is active. Provided there is no evidence of nephritis during this period, patients should have a urinalysis on a monthly basis for 6 months after all other manifestations have resolved.

Patients who develop nephritis at any time should have blood pressure and serum creatinine monitored periodically until the nephritis has resolved.

Children with overt renal disease, e.g. complicated by nephrotic syndrome, hypertension or renal insufficiency at presentation should be referred to the renal physicians for management, as a renal biopsy may be required to predict prognosis more precisely. These patients usually require prolonged follow up.

Recurrence

A recurrence rate of 40% has been reported for symptoms of HSP. The recurrences tend to resemble the original episode but are usually milder and of shorter duration.

Recurrences appear to be more common in those patients with nephritis.

With each recurrence of disease, patients should have urinalysis and blood pressure checked.

HSP nephritis may recur in transplanted kidneys. Recurrence of the nephritis and extra-renal manifestations are more likely in recipients of living related-donor kidneys than of cadaveric kidneys. It is recommended that transplantation is delayed for 12–24 months following disappearance of the purpuric lesions.

Complications

• Acute renal insufficiency with elevation of serum creatinine can develop in patients with HSP nephritis.
• Patients can also develop nephrotic syndrome. In this situation the urine protein excretion is >50 mg kg–1 per 24 hours, with oedema and hypoalbuminaemia.
• End-stage renal disease (ESRD) is a possible complication of HSP nephritis.
• Orchitis is a well-described complication of HSP and it may mimic testicular torsion.
• Testicular torsion can be an infrequent complication of scrotal oedema.
• Gastrointestinal bleeding and intussusception can complicate HSP.

Prognosis

Though the overall prognosis is excellent for HSP, nephritis is the one manifestation that can become chronic. Renal disease develops in 5%. Prognosis depends on the severity and extent of renal involvement. In general, patients with isolated haematuria, with or without trivial proteinuria, have a uniformly good prognosis. However, up to 50% of children with nephritis associated with nephrotic syndrome may progress to renal insufficiency. Approximately 20–50% will have persistent urinary abnormalities on long-term follow up but only 1% of patients progress to ESRD.

Clinical presentation is helpful but is not a precise determinant of prognosis. Severity of renal disease and the ultimate outcome correlate more closely with histopathological changes on renal biopsy and the degree of proteinuria at presentation. Poor prognosis is associated with crescent formation involving more than 50% of the glomeruli.

Regardless of clinical presentation or histological changes, all patients with nephritis need prolonged follow up since deterioration in renal function may occur in some patients many years later.

Prevention

There appears to be no single pathogen or environmental agent that has emerged as an important precipitating cause of HSP, thus there is no means of preventing HSP.

Controversies and future directions

A number of studies have addressed the question of whether early corticosteroid treatment prevents the delayed appearance of nephritis but the results are conflicting.
Further work is needed to explore the role of cytokines in determining the exclusive involvement of IgA1 in the immunopathogenesis of HSP. IgA has two subclasses, IgA1 and IgA2, but HSP is associated with abnormalities involving IgA1 rather than with IgA2.
The fundamental abnormality responsible for HSP and IgA nephropathy needs to be elucidated.
Role of other immunosuppressives?

Further reading

Chang W.-L., Yang Y.H., Wang L.C., et al. Renal manifestations in henoch Schonlein purpura: a 10 year clinical study. Ped Nephrol. 2005;20:1269-1272.

Cronan K., Norman M. Renal and electrolyte emergencies. In: Fleisher G., Ludwig S., editors. Textbook of pediatric emergency medicine. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2000:851.

Meulders Q., Pirson Y., Cosyns J.P. Course of Henoch–Schönlein nephritis after renal transplantation. Transplantation. 1994;58:1179-1186.

Narchi H. Risk of longterm renal impairment and duration of follow up recommended for Henoch Schonlein Purpura with normal or minimal urinary findings: a systematic review. Arch Dis Child. 2005;90:916-920.

Oner A., Tinaztepe K., Erdogan O. The effect of triple therapy on rapidly progressive type of Henoch–Schönlein nephritis. Paediatr Nephrol. 1995;9:6-10.

Saulsbury F.T. Henoch–Schönlein purpura in children – Report of 100 patients and review of the literature. Medicine. 1999;78(6):395-406.

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