Purpura

Purpura is a clinical sign defined by reddish-purple discoloration of the skin and mucous membranes caused by bleeding beneath the skin. It includes petechiae (tiny hemorrhages less than 2 mm) and larger purpura (2–10 mm). When bleeding results from inflammation of small vessels, the purpura is often palpable (palpable purpura). Purpura is a sign, not a disease, reflecting an underlying condition.

Common causes include small-vessel vasculitis (eg, IgA vasculitis/Henoch-Schönlein purpura, cryoglobulinemic vasculitis), thrombocytopenia or platelet dysfunction, and coagulation disorders. Non-palpable purpura can arise from fragile dermal capillaries in older adults (senile purpura), scurvy, infection, trauma, or drug effects.

Evaluation emphasizes distinguishing palpable from non-palpable purpura and assessing systemic involvement. Laboratory testing typically includes CBC with platelets, coagulation studies, metabolic panel, and urinalysis. Depending on suspicion, tests for inflammatory markers or autoimmune serologies may be performed. Skin biopsy may be needed to confirm vasculitis.

Management targets the underlying cause. Mild purpura from trauma or minor platelet dysfunction may require little or no treatment. Purpura due to vasculitis or coagulopathy is treated by addressing the cause, which may involve steroids or immunosuppression, antibiotics for infection, or reversal of anticoagulation. Urgent evaluation is essential if fever, altered mental status, neck stiffness, or rapidly spreading purpura suggest a life-threatening process such as meningococcemia or DIC.

Prognosis depends on the underlying condition. Purpura is a sign rather than a disease, with outcomes ranging from self-limited to life-threatening if initial assessment is delayed.