Atypical Henoch-Schonlein purpura? Consider polyarteritis nodosa!

We describe the case of a previously healthy 12-year-old boy admitted to a tertiary paediatric centre with the clinical diagnosis of Henoch-Schonlein purpura (HSP). Symptoms on admission included a generalised rash, colicky abdominal pain, hypertension, proteinuria and fresh rectal bleeding. Abdominal pain and distension worsened and serial ultrasounds suggested bowel ischaemia. He underwent repeat laparotomy and bowel resection, with slow improvement after the second laparotomy. The severity of systemic involvement (gastrointestinal, cardiac, renal and skin) made the initial diagnosis of HSP questionable. Immunohistochemistry of skin biopsies was negative for HSP. Histopathology of the bowel specimen revealed features of necrotising small and medium vessel vasculitis in keeping with polyarteritis nodosa.