The features of Henoch Schonlein Purpura, the most common vasculitis affecting children can be recalled by the ARENA mnemonic [A = abdominal pain (65% of cases), R = rash (100%), E = edema, N = nephritis (40%), A = arthritis (75%)].
Whenever I am considering a pediatric patient with abdominal pain, I like to review my post Pediatric Acute Abdominal Pain Posted on July 13, 2016. The post is a quick but complete review of pediatric abdominal pain.
The following, HSP and Intussusception, PUBLISHED JUNE 8, 2012 · UPDATED SEPTEMBER 22, 2012, is from Dr. Sean Fox’s outstanding Pediatric EM Morsels blog:
We have discussed intussusception before and have noted that it can be a difficult diagnosis to make as the “classic” triad of colicky abdominal pain, vomiting, and currant jelly stools only occurs in 21% of cases. Furthermore, the precipitating condition that produced the lead point that caused the intussusception can also distract you from making the diagnosis. Is this colicky abdominal pain due to the viral illness the child has or is it due to telescoped intestine that started at the hypertrophied Peyer’s Patch? Another great example of this is Henoch-Schonlein Purpura (HSP).
HSP is the most common vasculitis affecting children.
- It is self-limiting and generally resolves after ~4 weeks, but nephritis can persist.
- Clinical manifestations are due to widespread leukocytoclastic vasculitis from IgA deposition in blood vessel walls.
- Dominant Features (ARENA):
- Abdominal Pain (occurs in 65% of cases)
- May precede rash.
- Colicky pain, vomiting, and GIB are common (sounds like intussusception).
- May mimic acute surgical abdomen.
- Intussusception is rare, but known complication.
- Rash (occurs in 100% of cases)
- Sine qua non
- Purpura, classically palpable. Starts on legs and buttocks. Not itchy.
- Not associated with thrombocytopenia!
- May be preceded briefly by urticarial or maculopapular rash.
- Angioedema of the scalp, eyelids, back, feet, and/or perineum.
- Less common in older children.
- Nephritis (occurs in 40% of cases)
- Hallmark is hematuria.
- Substantial proportion will have gross hematuria.
- May not develop for weeks to months after diagnosis (needs close follow-up).
- May become a chronic problem.
- Arthritis (occurs in 75% of cases)
- Commonly involves knees and ankles.
- Self-limiting and non-deforming.
- Can be severely painful.
- May precede the rash and, thus, confound diagnosis.
Intussusception and HSP
- Intussusception can be seen as a complication of HSP in 2-6% of cases.
- HSP associated intussusception generally occurs in children >2yrs of age.
- 70% occur in ileoileal locations, with only 30% being ileocolic (unlike typical intussusception, which occurs most commonly at ileocolic locations.
- Contrast enema may not diagnose it, because of the ileoileal location.
- Ultrasound is preferred imaging modality, augmented by serial examinations.
- Upper GI Series with small bowel follow-through may be necessary as well.
Saulsbury FT. Henoch-Schonlein Purpura. Current Opinion in Rheummatology: Jan. 2001; Vole 13(1). Pp.35-40.
Little KJ, Danzl DF. Intussusception associated with Henoch-Schonlein Purpura. The Journal of Emergency Medicine: 1991; Vole 9 (supp 1). Pp. 29-32.