Autoimmune & autoinflammatory
Cutaneous small-vessel vasculitis
Crops of purple, non-blanching spots on the lower legs signal small-vessel vasculitis in the skin - most cases are self-limiting, but every case earns a check for triggers and internal involvement.
Key points
The essentials at a glance.
What to look out for, which tests matter, who treats it, and what usually happens next.
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Hallmark: palpable purpura on the lower legs - raised, purple-red, non-blanching lesions
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Common triggers: recent infections, new medications (a careful drug history pays off), and occasionally underlying systemic disease
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Skin biopsy confirms leukocytoclastic vasculitis; immunofluorescence looks for IgA
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Minimum screen: urinalysis, blood pressure, renal function, and symptom review for gut, joint and nerve involvement
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Most single episodes settle in weeks with rest, elevation and support stockings; recurrent or systemic cases need specialist care
Understanding it
About Cutaneous small-vessel vasculitis.
When immune complexes clog the tiniest skin vessels, red cells leak into the skin producing purpura you can feel under the fingertip - gravity concentrates it on shins and ankles. Roughly half of cases follow an identifiable provocation, with respiratory infections and newly started drugs (antibiotics prominently) leading the list; a minority unmask a systemic vasculitis, a connective tissue disease, a cryoglobulin or, rarely, malignancy. The skin, in other words, may be the whole story or merely the visible page of it.
The assessment logic is fixed: biopsy a fresh lesion, take a forensic drug and infection history, dipstick the urine and check kidney function - because the same process that speckles the shins can inflame glomeruli silently. Uncomplicated skin-limited disease needs little more than time, leg elevation and compression; recurrence, ulceration or any internal signal moves care to dermatology and rheumatology jointly. In many parts of the UK, a routine NHS referral to the relevant specialist clinic currently means waiting many months - sometimes more than a year for the rarest conditions - whereas an initial appointment with a private consultant is typically available within around two weeks, with investigations arranged soon after.
Frequently asked
Common questions about Cutaneous small-vessel vasculitis.
Quick, plain-English answers to what people ask us most.
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What is cutaneous small-vessel vasculitis?
Cutaneous small-vessel vasculitis is inflammation of the small blood vessels in the skin, typically producing crops of purple, non-blanching spots (palpable purpura), most often on the lower legs.
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What causes cutaneous small-vessel vasculitis?
Most cases are self-limiting and triggered by a recent infection or medication, though it can occasionally be associated with an underlying autoimmune condition or, rarely, an underlying malignancy, which is why an appropriate workup is important.
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What are the symptoms of cutaneous small-vessel vasculitis?
The characteristic sign is crops of purple, raised spots (palpable purpura) that don't blanch (turn pale) when pressed, most commonly on the lower legs, sometimes accompanied by mild itching or discomfort.
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Is cutaneous small-vessel vasculitis dangerous?
Most cases are self-limiting and resolve without serious consequences, but proper assessment is needed to rule out an underlying cause requiring specific treatment, and rarely, involvement of internal organs such as the kidneys can occur.
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How is cutaneous small-vessel vasculitis treated?
Mild, self-limiting cases often just need monitoring and treatment of any identified trigger. More persistent or severe cases may need steroid or other immune-modulating treatment, particularly if there's evidence of internal organ involvement.
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How long does cutaneous small-vessel vasculitis last?
Most self-limiting cases resolve within a few weeks once the trigger (such as an infection or medication) is identified and removed, though some cases can be more persistent or recurrent.
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Can cutaneous small-vessel vasculitis come back?
Yes, some people experience recurrent episodes, particularly if there's an underlying chronic trigger or associated condition that hasn't been fully identified or addressed.
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How is the underlying cause investigated?
Workup typically includes blood tests, urine testing (to check for kidney involvement), and sometimes a skin biopsy, looking for evidence of infection, medication reaction, autoimmune disease, or other underlying triggers.
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Cutaneous small-vessel vasculitis vs other rashes - how can you tell?
The characteristic non-blanching, palpable purple spots (rather than a flat, blanching rash) point specifically towards vasculitis, which is why a proper clinical assessment is important to distinguish it from other rash types.
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When should I see a doctor about a purple rash?
See a doctor promptly for a new rash of purple, non-blanching spots, particularly if accompanied by fever, joint pain, or reduced urine output, as this needs assessment to rule out organ involvement. A private dermatology review can often be arranged within about two weeks.