Henoch-Schönlein purpura (HSP)

Question 1

Henoch-Schönlein purpura (HSP)

Answer 1

Henoch-Schönlein purpura (HSP) is the most common form of systemic vasculitis in children and is characterized by IgA deposition in affected blood vessels. The renal lesion is a mesangioproliferative GN with mesangial IgA deposition, indistinguishable from IgAN.

Question 2

Henoch-Schönlein purpura (HSP)

Epidemiology

Answer 2

Although HSP may occur at any age, it is most common during childhood between the ages of 3 to 15. There is a slight male predominance.

Question 3

Henoch-Schönlein purpura (HSP)

Epidemiology

Answer 3

Most cases occur in the winter, spring, and autumn months, which may be because of its association with preceding upper respiratory tract infections.

Question 4

Henoch-Schönlein purpura (HSP)

Etiology and Pathogenesis

Answer 4

The exact cause of HSP remains unknown. There are, however, many factors that suggest a common pathogenic pathway operating in HSP and IgAN.

Question 5

Henoch-Schönlein purpura (HSP)

Etiology and Pathogenesis

Answer 5

Identical twins have been reported where one presents with IgAN and the other with HSP. HSP developing on a background of IgAN is described in both adults and children.

Question 6

Henoch-Schönlein purpura (HSP)

Etiology and Pathogenesis

Answer 6

Both diseases share similar findings on kidney biopsy, and they also share changes in the complement of serum IgA1 O-glycoforms. There is a similar association between mucosal infection and presentation of disease.

Question 7

Henoch-Schönlein purpura (HSP)

Natural History

Answer 7

The kidney disease that accompanies HSP is often transient and self limited in nature, with hematuria or proteinuria typically resolving within weeks of presentation.

Question 8

Henoch-Schönlein purpura (HSP)

Natural History

Answer 8

AKI due to crescentic HSP nephritis is more common than crescentic IgAN (although still uncommon), and AKI tends to occur early in the course of the disease. The prognosis of patients who have transient HSP is generally very good. However, up to 10% of patients with HSP nephritis will develop ESRD.

Question 9

Henoch-Schönlein purpura (HSP)

Clinical Features

Answer 9

The classic tetrad of symptoms in HSP is a palpable purpuric rash, arthritis/arthralgia, abdominal pain, and kidney disease. Symptoms appear in any order and can evolve over days to weeks.

Question 10

Henoch-Schönlein purpura (HSP)

Clinical Features

Answer 10

The rash is classically distributed on extensor surfaces, with sparing of the trunk and face. It typically appears in crops, and is symmetrically distributed.

Question 11

Henoch-Schönlein purpura (HSP)

Clinical Features

Answer 11

Polyarthralgia is common, and is usually transient and migratory. There is often swelling and tenderness but no chronic destructive damage.

Question 12

Henoch-Schönlein purpura (HSP)

Clinical Features

Answer 12

Gastrointestinal symptoms often appear after the rash. Abdominal pain is usually mild and transient, but it may be severe and lead to gastrointestinal hemorrhage, bowel ischemia, intussusception, and perforation.

Question 13

Henoch-Schönlein purpura (HSP)

Clinical Features

Answer 13

Kidney involvement (HSP nephritis) typically manifests as transient asymptomatic microscopic hematuria and/or proteinuria.

Question 14

Henoch-Schönlein purpura (HSP)

Clinical Features

Answer 14

More severe complications, such as nephrotic syndrome or rapidly progressive deterioration of kidney function, occur less frequently and are more common in adults than in children.

Question 15

Henoch-Schönlein purpura (HSP)

Pathology

Answer 15

As in IgAN, elevated serum IgA levels are found in 30% to 50% of adult patients with HSP. Serum IgA levels do not correlate with disease activity or severity.

Question 16

Henoch-Schönlein purpura (HSP)

Pathology

Answer 16

Similarly, changes in the levels of undergalactosylated IgA1 O-glycoform levels are not sensitive nor specific enough to be used as a diagnostic test in HSP. Confirmation of the clinical diagnosis requires histologic evidence of IgA deposition in affected tissue, often the skin or kidney.

Question 17

Henoch-Schönlein purpura (HSP)

Skin Biopsy

Answer 17

Biopsy of the skin rash typically shows a leukocytoclastic vasculitis. IgA immune complex deposition can be seen using immunofluorescent staining, but detection of IgA in the skin is unreliable. If a tissue diagnosis is required, a kidney biopsy should be performed in the presence of nephritis.

Question 18

Henoch-Schönlein purpura (HSP)

Kidney Biopsy

Answer 18

Kidney biopsy is usually reserved for adult cases of diagnostic uncertainty or when a child presents with more severe renal involvement. Histologic features are the same as those in IgAN.

Question 19

Henoch-Schönlein purpura (HSP)

Management

Answer 19

There is little evidence to guide the treatment of HSP nephritis, and that which exists is derived from small retrospective case series.

Question 20

Henoch-Schönlein purpura (HSP)

Management

Answer 20

Patients with hematuria, proteinuria, and mildly reduced GFR do not require any specific treatment, and the nephritis usually resolves spontaneously.

Question 21

Henoch-Schönlein purpura (HSP)

Management

Answer 21

In patients with crescentic HSP nephritis typified by a rapidly progressive loss of kidney function, there is limited evidence that high-dose corticosteroids are beneficial.

Question 22

Henoch-Schönlein purpura (HSP)

Management

Answer 22

Regimens include pulsed methylprednisolone followed by a 3-month course of oral prednisolone. There is currently no conclusive evidence that other immunosuppressive agents, including cyclophosphamide or azathioprine, or other interventions, such as plasmapheresis, have any beneficial effect on outcome.

Question 23

Henoch-Schönlein purpura (HSP)

Follow-Up

Answer 23

Patients should be monitored as for IgAN. As with other forms of glomerular disease, those patients with persistent proteinuria are at highest risk of developing progressive CKD.

Question 24

Henoch-Schönlein purpura (HSP)

Transplantation

Answer 24

Kidney transplantation is the treatment of choice in patients with ESRD resulting from HSP nephritis. As with IgAN, recurrence of mesangial IgA deposition may occur, although loss of the graft to HSP nephritis is less common and tends to occur in patients who had an aggressive original disease.

Question 25

Henoch-Schönlein purpura (HSP)

Transplantation

Answer 25

Kidney transplantation should be delayed for 12 months from date of presentation.

Question 26

Henoch-Schönlein purpura (HSP)

Pregnancy

Answer 26

Evidence from cohort studies of children with HSP suggests that all women with a history of HSP should be carefully monitored during pregnancy, even if they had no evidence of kidney disease at the time of diagnosis. These women are at increased risk of developing hypertension and proteinuria during pregnancy.