Henoch-Schonlein Purpura

Henoch-Schonlein Purpura
HSP is the most common cause of non-thrombocytopenic purpura in children. It was named after two German doctors from the 19th century. It is type of a vasculitis of small vessels and is also known as anaphylactoid purpura.

Epidemiology.
The etiology is unknown but it typically follows an upper respiratory tract infection.

The possible causes include:

1. Infections – there are a lot of infectious agents which can be connected to Henoch schonlein purpura in children, including the Streptococcus, Adenovirus, Epstein-Barr virus, varicella etc.
2. Medications – These include penicillin, erythromycin, quinine, quinidine and ampicillin.
3. Vaccines – Including the vaccines for typhoid and paratyphoid A and B, measles, yellow fever and cholera.
4. Other – Rarely, it can also be caused by food allergens or insect bites.

More frequent in children than adults.
Most cases occur between 2-8 yr of age.
Most frequently seen in the winter months.
Males are affected twice as frequently as females.
The overall incidence is estimated to be 9/100,000 population.

In GMC Fujairah we have diagnosed two cases in last 2 years, both were boys of 6 and 8 years of age.

Pathology.
This illness is considered by histopathology to be an IgA-mediated vasculitis of small vessels.

Most children present with low-grade fever and fatigue.

The hallmark of the disease is the rash, beginning as pinkish maculopapules that initially blanch on pressure and progress to petechiae or purpura, which are characterized clinically as palpable purpura that evolve from red to purple to rusty brown before they eventually fade.

The lesions tend to occur in crops, last from 3-10 days, and may appear at intervals that vary from a few days to as long as 3-4 mo.

Edema occurs primarily in dependent areas-for example, below the waist, over the buttocks (or on the back and posterior scalp in the infant), or in areas of greater tissue distensibility, such as the eyelids, lips, scrotum, or dorsum of the hands and feet.

Arthritis, is usually localized to the knees and ankles and appears to be concomitant with edema and resolve after a few days without residual deformity or articular damage but may recur during a subsequent reactive phase of the disease.

Intermittent abdominal pain that is often colicky in nature.

Other GI symptoms include diarrhea (with or without visible blood), or hematemesis.

Intussusception may occur, which is suggested by an empty right lower abdominal quadrant on physical examination or by currant jelly stools.

Nephritis occurs in 25-50% of children.

Hepatosplenomegaly and lymphadenopathy may also be present during active disease.

A rare but potentially serious outcome of central nervous system (CNS) involvement is the development of seizures, paresis, or coma.

Other rare complications include rheumatoid-like nodules, cardiac and eye involvement, mononeuropathies, pancreatitis, and pulmonary or intramuscular hemorrhage.

Diagnosis.
The pattern of crops of palpable purpuric lesions of similar hue in dependent areas of the body is characteristic of HSP.

Differential diagnosis:

• Acute abdomen: The recognition of peritoneal exudate, enlarged mesenteric lymph nodes, segmental edema, and hemorrhage into the bowel may prevent unnecessary laparotomy for acute abdominal pain.
• Palpable purpura can occur in meningococcemia.
• The presentation of unremitting fever, a maculopapular rash that does not reappear in crops but is prominent on the lower extremities, and peripheral arthritis suggests Kawasaki disease.
• HSP must be distinguished from systemic-onset juvenile rheumatoid arthritis, in which the salmon-pink rash is evanescent and maculopapular, with swelling that does not extend beyond the joint.

Laboratory Findings.
Routine laboratory tests are neither specific nor diagnostic.

CBC: Anemia with moderate thrombocytosis and leukocytosis.

ESR: may be elevated.

Urine routine: RBC’s, WBC’s, casts, or albumin may be present.

Antibodies: 50% of patients have elevated concentrations of IgA as well as IgM. Anticardiolipin or antiphospholipid antibodies may be present. ANCA, ANA and Rh factors are absent.

Abdominal USG: Intussusception is usually ileoileal in location; barium enema may be used for both identification and nonsurgical reduction.

Biopsy at pupura site, shows leukocytoclastic angiitis.

Renal biopsy may show IgA mesangial deposition and occasionally IgM, C3, and fibrin.

Treatment.
Symptomatic treatment, including adequate hydration, bland diet, and pain control with acetaminophen, is provided for self-limited complaints of arthritis, edema, fever, and malaise.

Bed rest and limb elevation to decrease local edema. Scrotal elevation if scrotal edema.

Reduction (by air or barium) or resection of the intussusception.

Oral or intravenous corticosteroids (1-2mg/kg/24hr) for gastrointestinal and CNS complications.

Management of renal involvement is the same as for other forms of acute glomerulonephritis.

Aspirin only if anticardiolipin or antiphospholipid antibodies are identified and thrombotic events have occurred.

Alternate-day colchicine (0.6mg/24hr every other day) can be given for rheumatoid nodules.

Complications.
The major complications of HSP are renal involvement, including nephrotic syndrome, and bowel perforation.

An infrequent complication of scrotal edema is testicular torsion, which is quite painful and must be treated promptly.

Prognosis.
HSP is a self-limited vasculitic disease with an excellent overall prognosis.

Fewer than 1% of patients with HSP develop persistent renal disease and fewer than 0.1% develop serious renal disease.

Rarely, death may occur during the acute phase of the disease as a result of bowel infarction, CNS involvement, or renal disease.

References:

1. Nelson text book of pediatrics 18th edition
2. Recent advances in pediatrics