Henoch-Schönlein purpura

Case:

This 7-years old boy was seen in the emergency department about a month ago with the main complaint of sudden onset of colicky abdominal pain. After been given pain relief, his abdomen was soft, non tender and non guarded. He was, otherwise, fully alert and conscious; vital signs are normal, not toxic looking and no signs of meningisms.

The easy part is he has been suspected of having Henoch Schonlein Purpura from his first visit based the skin rash appearance about a week earlier.

However, we should not be misled by any preconceived diagnosis without examining him carefully. If he presented with signs of meningism and appeared toxic looking, the first thing that comes to my mind with that kind of rash appearance would be have been meningococcal septicaemia!! As emergency physician, I must rule out meningococcal septicemia first especially if the history fits. In fact, all literature cited meningococcal septicemia as a differential for the rash per se.

Definition of Henoch-Schönlein purpura (HSP)

HSP is described as non-thrombocytopenic, purpuric and systemic vasculitis of childhood that occurs twice as often in males as in females.

Every word in that definition is keyword to understand HSP:

Henoch-Schönlein purpura is a

Nonthrombocytopenic

- Very important to know that HSP is non-thrombocytopenic because a normal platelet count helps to differentiate HSP from thrombocytopenic purpura

purpuric

- And it is palpable

- Palpable purpura is present in almost 100% of patients with Henoch-Schönlein purpura

- Is a presenting sign in 50% of patients

- Some patients present with predominantly smaller petechial lesions, some present with mainly purpuric lesions, and others present with a mixture of lesion types, some may have target-like lesions (central punctate hemorrhage surrounded by circumferential regions of pallor and hemorrhage)

- The characteristic of the purpura is it is gravity and pressure dependent. This may cause a typical sock line (for those who wear socks regularly – not present in this boy as he did not wear sock)

- Note: The sock line picture is clearly seen in an article by Ponce de Souza et al. in 2005. Click here to go to the article.

systemic vasculitis of

- HSP essentially is an IgA-mediated systemic vasculitis of small blood vessels

- There is diffuse vasculitis secondary to deposition of immune complexes

- Unknown cause but has been associated with various factors, especially a preceding RTI (more than half) particularly a group A strep organism

- Other than that, literature also shows that it has been associated with vaccinations, allergens in foods, drug reactions, etc etc.

- Note: this blog post is not meant to be an exhaustive description of HSP because there are some very good articles available free online. See references below for the links

- Though it is systemic, it is often described as presenting with classical triad of symptoms: a palpable purpuric rash on the lower extremities, abdominal pain or renal involvement, and arthritis.

- This patient has typical rash, as well as severe acute abdominal pain. In fact, when he first arrived in ED, he was groaning in pain, but his pain much improved after given pain relief

- The most serious sequela of HSP is the renal involvement because it can progress to ESRF

- The most common manifestation of renal disease in HSP is hematuria.

childhood

- in fact, HSP is the most common form of vasculitis in children

- Approx 75% of cases occur in children between two and 11 years of age.

- Twice as often in males as in females (this patient is a boy)

References:

Note: these three articles are excellent articles for review.

1. Kraft DM, McKee D, Scott C. Henoch-Schonlein purpura: a review. Am Fam Physician 1998; 58 (2):405-8, 11.

http://www.aafp.org/afp/980800ap/kraft.html
(This article is a good description of HSP, easy to understand)

2. Leung AK, Chan KW. Evaluating the child with purpura. Am Fam Physician 2001; 64 (3):419-28.

http://www.aafp.org/afp/20010801/419.html
(This is a superb article regarding the approach of purpura in general)

3. Ponce de Souza E, Usatine RP. Palpable purpura and a visible sock line. J Fam Pract 2005; 54 (6):520-3.

http://www.jfponline.com/pages.asp?aid=1957&UID=#bib1
(This article has good pictures on the sock lines in the distribution of rash in gravity dependant position. Wonder how the distribution of the rash would be if one of the patient is an astronaut!)