Henoch-Schonlein purpura: Clinical sciences

Henoch-Schönlein purpura, or HSP for short, is the most common systemic vasculitis of childhood and typically affects the skin, intestines, and kidneys. HSP is also known as IgA vasculitis, since it’s associated with vasculitis of small blood vessels due to immunoglobulin A deposition. While HSP is a self-limited condition that often improves after a few weeks of supportive care in the outpatient setting, some children may develop HSP nephritis, which can result in kidney injury and, in rare cases, lead to kidney failure.

Now, when a patient presents with a chief concern suggesting HSP, you should start by obtaining a focused history and physical examination. Most children with HSP are between 3 and 15 years old, and often present with a reddish-purple rash. Some patients may also complain of migratory joint pain that mainly affects the knees and ankles. Some patients may also present with colicky abdominal pain. HSP is associated with various infectious organisms, such as group A streptococcus or other upper respiratory infections, so be sure to ask whether they have recently recovered from an infection.

The physical exam typically reveals palpable purpura, which is a reddish-purple rash consisting of elevated, firm, and hemorrhagic papules and plaques that can be detected by touch. These skin changes typically appear in clusters on the legs and buttocks. You may also notice edema of the hands or feet, or in other gravity-dependent areas, such as the periorbital area or the scrotum. Additionally, you might detect swelling of the soft tissues around the joints, tenderness of the joints, or even joint effusion, especially in the knees or ankles, but overlying joint erythema does not usually occur..

With these clinical findings, you should suspect HSP. Once you suspect HSP, your next step is to order labs. These should include a CBC, PT and PTT, and serum creatinine. In addition, send urine for urinalysis and a urine protein level, and send stool for a fecal occult blood test. Typically, a skin biopsy isn’t required to diagnose HSP; however, if the clinical presentation is unusual, you may order one to confirm the diagnosis.

As far as labs go, the CBC, PT, and PTT are typically normal. This is especially important, since in patients with thrombocytopenia or an abnormal coagulation profile, you may need to consider sepsis, leukemia, or another cause.

The fecal occult blood test might be guaiac-positive, indicating gastrointestinal involvement and mucosal bleeding. If you do order a skin biopsy, it will show leukocytoclastic vasculitis of the small blood vessels, with IgA deposition. With these clinical findings and supporting results, you can diagnose HSP.

Now here’s a clinical pearl to keep in mind! GI involvement is seen in a majority of patients with HSP, most often in the form of upper and lower GI tract bleeding and intestinal edema. These findings can lead to complications, such as intussusception, bowel ischemia, necrosis, or even perforation. So, don't forget to monitor abdominal pain closely and investigate further if abdominal pain worsens or changes acutely.

So, now that you’ve diagnosed HSP, your next step is to assess kidney involvement using a combination of blood pressure measurements and lab results. Let’s first discuss individuals with no kidney involvement. If the blood pressure is normal for age; the urinalysis shows no blood or protein; the urine protein is negative; and serum creatinine is normal, diagnose HSP with no kidney involvement. In this case, treatment consists of supportive care, including adequate hydration. Additionally, you can give NSAIDs for joint pain and corticosteroids for severe abdominal pain.

Now, here’s a high yield fact to keep in mind! While corticosteroids can reduce the abdominal pain associated with HSP, they don’t impact its clinical course or prognosis, and they don’t prevent progression to HSP nephritis. Also, make sure to taper corticosteroids slowly because rapid tapering increases the risk of a disease rebound or flare!