DISCUSSION
The report showed leukocytoclastic vasculitis, in which activated lymphocytes attack the inner lining of blood vessels, causing them to leak blood into the surrounding interstitial spaces. Besides the extravasated red blood cells, nuclear dust (remnants of the attacking lymphocytes) is also seen.
These biopsy findings, in context with the patient’s history, help to confirm the diagnosis of Henoch-Schönlein purpura (HSP), an IgA-mediated disease that causes widespread vasculitis of small vessels throughout the body. Besides affecting the skin, this process can injure the gastrointestinal tract, joints, kidneys, and even lungs. As this case illustrates, it almost always presents with a palpable, purpuric, widespread rash, abdominal pain, fever, joint pain, and bloody stools.
HSP is seen primarily in children; in the US, 75% of cases occur in those ages 2 to 5. The most consistent presenting symptoms in this population include rash, abdominal pain, and joint pain. When fever is present, it is typically mild.
A variety factors can trigger HSP, including medications (eg, penicillin, NSAIDs, sulfa) and infection (with organisms such as mycoplasma, mononucleosis, strep, Legionella)—but many cases are simply idiopathic. History of upper respiratory infection, pharyngitis, or intestinal infection is found in 75% of young HSP patients. Antecedent vaccinations have also been reported as a potential trigger.
The diagnosis of HSP is primarily clinical, based on a combination of signs and symptoms and the exclusion of other items in the differential. Besides bloodwork to rule out end-organ (eg, renal) damage, a skin biopsy of the purpuric rash is necessary to establish the type of vasculitis.
Fortunately, most HSP patients recover uneventfully; the exception is the occasional patient with renal complications. The case patient successfully recovered following treatment with oral antibiotics (for presumed strep) and a three-week course of prednisone.
TAKE-HOME LEARNING POINTS
- A purpuric rash should prompt a punch biopsy to search for vasculitis.
- A widespread, palpable, purpuric rash accompanied by systemic symptoms of abdominal pain, arthralgia, fever, and malaise is suggestive of serious disease. In younger patients, Henoch-Schönlein purpura (HSP) should be a major suspect.
- Drugs, bugs, and vaccinations are all possible triggers for HSP.
- Once the diagnosis of HSP is made, monitoring for end-organ damage is essential.