Purpura

Purpura represents blood outside vessels in skin or mucosa and does not disappear with pressure.

Apply a transparent slide, assess elevation and examine mucosa; a photograph cannot establish these findings.

Describe size, dependent or widespread distribution, elevation, blistering and necrosis; distinguish petechiae from bruises.

Possible causes include thrombocytopenia, platelet dysfunction, coagulation disorders or vascular fragility; palpable lesions suggest vasculitis.

Erythema usually blanches; cutaneous vasculitis must be distinguished from bleeding caused by haemostatic abnormalities.

Look for arthralgia, abdominal pain, haematuria and respiratory symptoms; platelet count, creatinine and urinalysis guide investigation.

Associated renal, pulmonary or gastrointestinal findings warrant prompt assessment for systemic disease.

Purpuric appearance does not establish vasculitis; biopsy of a suitable lesion may be needed.

Describe the bleeding, check platelets and investigate vascular or systemic involvement according to context.

• Purpura: Causes, Types and Images ↗
• Cutaneous small vessel vasculitis ↗

Documentary review: 2026-10-12