The Bottom Line: About half of cases are idiopathic. The remainder are most often either drug induced or post infectious.
- Viral upper respiratory infection or streptococcal pharyngitis frequently precede the onset of IgA vasculitis by 1 to 2 weeks.
- 40% of cases are attributable to an infectious cause.
- Medication exposure may be to blame in around 20%.
- In adults, paraneoplastic IgA may be considered; 90% of such patients are male.
- As with small vessel cutaneous vasculitis as a whole, a significant fraction of cases have no identifiable cause.
Reference: Micheletti RG, Werth VP. Small vessel vasculitis of the skin. Rheumatic Diseases Clinics of North America. 2015;41(1):21-32. doi:10.1016/j.rdc.2014.09.006
Summary: Small vessel vasculitis of the skin has been referred to interchangeably using a number of terms: “cutaneous leukocytoclastic vasculitis,” or simply “leukocytoclastic vasculitis,” “hypersensitivity vasculitis,” “cutaneous leukocytoclastic angiitis,” and “cutaneous small vessel vasculitis” (Micheletti and Werth, 2015).
Small vessel vasculitis can also be due to an underlying connective tissue disease such as systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis, or dermatomyositis, and may, be the presenting sign of such disease.
Vasculitis due to underlying connective tissue disease may be associated with more significant internal involvement.
Cutaneous manifestations such as palpable purpura and urticarial lesions can also be a feature of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis with overlapping involvement of small and medium-sized cutaneous vessels.
A small percentage of patients (<5%) may have an underlying hematologic or solid organ malignancy.
Vasculitis tends to appear 7 to 10 days after exposure to a drug or infectious trigger and a mean of 6 months after the onset of an underlying medical condition. In practice, however, the range and timing of onset varies greatly.