What is Small Vessel / Cutaneous Vasculitis?
Cutaneous small vessel vasculitis is inflammation of the smallest blood vessels in the skin, appearing as raised red-purple spots that do not fade when pressed, usually on the lower legs. Most cases follow an infection or a medicine and settle within weeks — but the assessment must establish whether the skin is the whole disease or the visible part of a systemic one.
Also called: Leukocytoclastic vasculitis, hypersensitivity vasculitis
Who gets Small Vessel / Cutaneous Vasculitis?
It occurs at any age. Common triggers include recent infection (particularly streptococcal or viral), medicines started in the preceding weeks — antibiotics, non-steroidal anti-inflammatories, diuretics and others — and, less often, an underlying autoimmune disease, chronic infection such as hepatitis C, or malignancy. In up to half of cases no trigger is ever identified.
What are the symptoms of Small Vessel / Cutaneous Vasculitis?
Not everyone has every symptom below, and having one does not confirm the diagnosis. These are the features that most often lead to assessment:
- Raised red or purple spots that do not blanch under pressure, typically on the lower legs and ankles
- Spots appearing in crops, sometimes after standing for long periods
- Burning or itching rather than pain, though lesions can be tender
- Blisters or ulcers in more severe cases
- Joint pain and swelling
- Fever and general malaise
- Abdominal pain or blood in the urine — features suggesting systemic involvement rather than skin-limited disease
How is Small Vessel / Cutaneous Vasculitis diagnosed?
A skin biopsy taken from a fresh lesion, ideally within 48 hours of it appearing, confirms the diagnosis; immunofluorescence identifies IgA deposits and therefore IgA vasculitis, which behaves differently.
The rest of the assessment is a search for a trigger and for systemic involvement: full blood count, kidney function, urine testing for blood and protein, liver function, inflammatory markers, ANCA, ANA, complement, cryoglobulins, and hepatitis B and C serology.
A careful medication history covering the preceding month is essential, since drug-induced disease usually resolves when the drug is stopped.
How is Small Vessel / Cutaneous Vasculitis treated?
Where a trigger is identified, removing it is the treatment: stopping the responsible medicine or treating the underlying infection.
For skin-limited disease: leg elevation, compression stockings, avoiding prolonged standing, and antihistamines or non-steroidal anti-inflammatories for symptoms. Most cases settle within three to four weeks.
Persistent, ulcerating or recurrent disease is treated with colchicine, dapsone, hydroxychloroquine or a short course of corticosteroids. Chronic recurrent disease may need immunosuppression.
Where kidneys, nerves or gut are involved, treatment follows the systemic vasculitis it belongs to rather than the skin.
Living with Small Vessel / Cutaneous Vasculitis
Most cases resolve completely and do not recur. Recurrent episodes over months warrant a second search for an underlying cause, since a proportion of cases that initially look skin-limited are the first sign of a systemic disease.
When should you see a rheumatologist?
A non-blanching purple rash on the legs should be assessed, particularly with fever, joint pain, abdominal pain, blood in the urine or new numbness — those features point to systemic involvement and need urgent review.
Common questions about Small Vessel / Cutaneous Vasculitis
Is this rash dangerous?
Often not — skin-limited cutaneous vasculitis usually settles within weeks. The assessment matters because the same rash can be the visible part of a systemic vasculitis affecting the kidneys, nerves or gut.
Why does it appear on my legs?
Gravity. Pressure in the small vessels of the lower legs is highest, so inflamed vessels leak there first. This is also why elevation and compression help.
Could my medicine have caused it?
Quite possibly. Antibiotics, anti-inflammatories, diuretics and many other drugs can trigger it, usually within days to weeks of starting. A full medication history covering the previous month is part of the assessment.
This page is general information to support a consultation. It is not a diagnosis, and it does not replace an assessment by a doctor who has examined you.