The differential diagnosis for HSP includes polyarteritis nodosa, a vasculitis with a different characteristic rash; acute abdomen, distinguished by the absence of purpura or arthralgia; meningococcemia, in which fever and meningeal signs may occur; hypersensitivity vasculitis, which arises due to prior exposure to medications or food allergens; and thrombocytopenic purpura, which is characterized by low platelet count.9
Treatment focuses on pain management
In the absence of renal disease, HSP commonly is treated with naproxen for pain management (dosage for children < 2 years of age: 5-7 mg/kg orally every 8-12 hours; dosage for children ≥ 2 years of age, adolescents, and adults: 10-20 mg/kg/d divided into 2 doses; maximum adolescent and adult dose is 1500 mg/d for 3 days followed by a maximum of 1000 mg/d thereafter).
For patients of all ages with severe pain and those with GI effects limiting oral intake of medication, use oral prednisone (1-2 mg/kg/d [maximum dose, 60-80 mg/d]) or intravenous methylprednisolone (0.8-1.6 mg/kg/d [maximum dose, 64 mg/d). Glucocorticoids may then be tapered slowly over 4 to 8 weeks to avoid rebound since they help with inflammation but do not shorten the course of disease. Steroids can ease GI and joint symptoms in HSP but will not improve the rash.
The classic tetrad of HSP includes the characteristic rash, abdominal pain, renal involvement, and arthralgia. Diagnosis usually is made clinically, but skin biopsy and direct immunofluorescence can confirm small vessel vasculitis with IgA deposits. More severe manifestations of HSP such as renal disease, hemorrhage, severe anemia, signs of intestinal obstruction, or peritonitis require rapid subspecialty referral.
Rachel Bramson, MD, Department of Primary Care, Baylor Scott and White Health, University Clinic, 1700 University Drive, College Station, TX 77840; [email protected]