The rash was consistent with nonblanching purpura. Two punch biopsies were performed for hematoxylin and eosin stain and direct immunofluorescence, which were consistent with IgA mediated small vessel vasculitis, or Henoch-Schoenlein purpura.
IgA small vessel vasculitis commonly occurs in children after a transient viral illness or as an allergic reaction to a medication. Nonblanching purpura occurs because small vessels have been cracked open by neutrophils and lymphocytes and leaked blood cells outside of the vascular circulation. Pressure fails to move these cells downstream, and thus, the skin does not blanch.
Joint pain is common, as is a self-resolving IgA mediated nephropathy. Approximately 1% to 3% of children will progress to end stage renal disease. IgA vasculitis also occurs in adults, with a higher portion developing nephropathy. In adults, lesions that present on the abdomen are suspected to correspond with gravity dependency and the total burden of IgA, leading to a higher risk for nephropathy.
The differential diagnosis of purpura is broad, but includes leukocytoclastic vasculitis, antineutrophil cytoplasmic antibodies-associated vasculitis, capillaritis, and disseminated intravascular coagulation.
The patient in this case was given topical triamcinolone 0.1% ointment to treat the rash. She returned 3 weeks later and her blood pressure was 160/105 mm Hg and she had protein and blood in her urine. The FP recommended a renal biopsy, which confirmed severe IgA nephropathy and end stage renal failure. She was given systemic steroids and ultimately received a renal transplant. Her outcome was atypical and unfortunate. Usually IgA vasculitis is benign and self-resolves with rest. Even when nephropathy is present, it typically resolves over weeks to months.
Photos and text for Photo Rounds Friday courtesy of Jonathan Karnes, MD (copyright retained). Dr. Karnes is the medical director of MDFMR Dermatology Services, Augusta, ME.