A five-year-old girl is brought to the pediatrician by her parents for concern about a rash on her legs and buttocks which began yesterday and has been progressive. The child also reports abdominal pain. Her parents also report that the child had three episodes of bloody diarrhea 3 days ago. Past medical history is unremarkable, and she does not take any medications. She is afebrile, and the remainder of the vital signs are within normal limits. On physical examination, she is noted to have palpable purpura on both lower extremities. Abdominal examination reveals diffuse tenderness to palpation that does not localize; there is some voluntary guarding. The left knee is noted to be swollen and diffusely tender to palpation. White blood cell count, hemoglobin, platelet count, prothrombin time, partial thromboplastin time, and liver function tests are all normal. A urinalysis reveals mild proteinuria and 5-10 red blood cells per high powered field.
Which of the following is the most likely diagnosis?
- A) Erythema infectiosus (fifth disease)
- B) Hemolytic uremic syndrome
- C) IgA vasculitis (Henoch-Schönlein purpura)
- D) Kawasaki disease
- E) Thrombotic thrombocytopenic purpura
C) IgA vasculitis (Henoch-Schönlein purpura)
IgA vasculitis (formerly Henoch-Schonlein purpura; HSP) is the most common vasculitis in children and occurs less commonly in adults. It presents with palpable purpura of the lower extremities with at least one of the following diagnostic criteria: diffuse abdominal pain, arthralgia or arthritis, renal involvement (hematuria and/or proteinuria), or a skin biopsy showing predominant IgA deposition. Skin biopsy typically is not required as IgA vasculitis can be diagnosed clinically in most cases. Thrombocytopenia and coagulopathy are not present. IgA vasculitis is a self-limited condition with a typical duration of 4 weeks. Initial treatment is supportive. Corticosteroids are indicated only for those with more severe disease, particularly renal involvement such as glomerulonephritis.
Answer choice A, Erythema infectiosum, is incorrect. Erythema infectiosum can be identified by an erythematous rash on the cheeks and a lacy rash on the extremities. Palpable purpura and renal findings are not present.
Answer choice B, Hemolytic uremic syndrome, is incorrect. Hemolytic uremic syndrome presents with the triad of hemolytic anemia, thrombocytopenia, and kidney injury. The normal CBC in this case rules out hemolytic uremic syndrome.
Answer choice D, Kawasaki disease, is incorrect. Kawasaki disease is one of the most common vasculitides of childhood, involving medium-sized arteries. A fever is the most consistent manifestation of Kawasaki disease. Kawasaki disease should be considered in all children with unxplained fever of 5 or more days’ duration. Erythema of the lips and oral mucosa, bilateral nonexudative conjunctivitis, extremity changes, and cervical lymphadenopathy typically develop after a brief nonspecific prodrome of respiratory or gastrointestinal symptoms.
Answer choice E, Thrombotic thrombocytopenic purpura, is incorrect. This condition is rare in the pediatric age group, and the normal platelet count rules out thrombocytopenia.
Key Learning Point
IgA vasculitis is a small vessel vasculitis that primarily affects children after an infection such as a viral upper respiratory infection. It presents with palpable purpura of the lower extremities with at least one of the following diagnostic criteria: diffuse abdominal pain, arthralgia or arthritis, renal involvement (hematuria and/or proteinuria), or a skin biopsy showing predominant IgA deposition. Thrombocytopenia and coagulopathy are not present.
Dr. Ted O'Connell
Dr. Ted O'Connell