Classification Tree for Hypersensitivity Vasculitis

HSV subsets

7. Purpura; history of medication at disease onset

6. Purpura; no history of medication at disease onset; age >16 at disease onset

4. Maculopapular rash and biopsy demonstrating eosinophils in a venule or arteriole; no purpura

2. Biopsy demonstrating granulocytes in the wall of a venule or arteriole; absence of purpura and maculopapular rash

Non-HSV subsets

5. Palpable purpura without medication at disease onset, age ≤16 at disease onset

1. No purpura or maculopapular rash; no granulocytes in vessel wall

3. Maculopapular rash; no purpura; no eosinophils in venule or arteriole

* The subset numbers also appear below the subset boxes in Figure 1. The classification tree yields a sensitivity of 78.5% and a specificity of 78.7%. See Table 3 for definition of criteria.