What is non-blanching purpura?

Non-Blanching Purpura: Recognition and Clinical Significance

Non-blanching purpura are hemorrhagic skin lesions that do not fade when pressure is applied, indicating extravasation of blood into the skin or subcutaneous tissues, and require urgent assessment as they may signal life-threatening conditions. 1

Definition and Pathophysiology

Non-blanching purpura are skin lesions characterized by:

• Red or purple discoloration of the skin
• Failure to blanch (fade) when pressure is applied (distinguishing feature)
• Result from extravasation of red blood cells from blood vessels into the skin or subcutaneous tissues
• May appear as petechiae (pinpoint hemorrhages <2mm) or larger purpuric patches

The key diagnostic feature is that, unlike blanching erythema, these lesions do not temporarily disappear when pressed with a glass slide or finger (diascopy test).

Clinical Significance and Urgency

Non-blanching purpura are a critical clinical sign that requires immediate attention because:

• They may represent the first visible sign of meningococcal disease, which has a high mortality rate if not treated promptly 1
• They can indicate severe systemic illness including sepsis, vasculitis, or coagulopathy
• In the context of fever, they are considered a high-risk sign for severe illness or death from sepsis 1

Common Causes

1. Infectious causes:

   • Meningococcal disease (Neisseria meningitidis)
   • Rocky Mountain Spotted Fever (RMSF) and other rickettsial diseases 1
   • Viral infections (including HHV-6) 2
   • Bacterial sepsis

2. Inflammatory/Immune-mediated:

   • Henoch-Schönlein purpura (HSP)/IgA vasculitis 3, 4
   • Small vessel vasculitis
   • Cryoglobulinemic vasculitis 5

3. Hematologic disorders:

   • Idiopathic thrombocytopenic purpura (ITP) 1, 6
   • Thrombotic thrombocytopenic purpura (TTP)
   • Disseminated intravascular coagulation (DIC)

4. Medication-induced:

   • Antiplatelet drugs (clopidogrel can rarely cause thrombotic thrombocytopenic purpura) 1
   • Anticoagulants

5. Other causes:

   • Trauma/mechanical pressure
   • Pigmented purpuric dermatoses 5, 7
   • Purpura fulminans (severe form with skin necrosis) 2

Clinical Assessment

When evaluating non-blanching purpura, assess for:

• Distribution: Lower extremities are common in HSP 3; acral distribution may occur in vasculitis 5; widespread distribution may indicate sepsis or coagulopathy
• Associated symptoms: Fever, headache, neck stiffness (meningitis); joint pain (HSP, vasculitis); abdominal pain (HSP) 3
• Vital signs: Assess for signs of sepsis using NEWS2 score 1
• Additional skin findings: Presence of eschars (rickettsial disease) 1; necrosis (purpura fulminans) 2

Immediate Management

For non-blanching purpura with suspected serious illness:

1. Urgent assessment of risk for sepsis or meningitis:

   • Calculate NEWS2 score 1
   • If score ≥5 or presence of non-blanching purpura with fever, consider high risk for sepsis

2. For suspected meningococcal disease or sepsis:

   • Administer antibiotics immediately (within 1 hour for high-risk patients) 1
   • Do not delay antibiotics for diagnostic tests 1
   • Obtain blood cultures before antibiotics if possible, but do not delay treatment

3. For suspected ITP:

   • Check complete blood count
   • If platelet count <20,000-30,000/μL with bleeding or <10,000/μL even without bleeding, consider treatment with corticosteroids or IVIg 6

Diagnostic Workup

• Complete blood count with platelet count
• Coagulation studies (PT, PTT, fibrinogen)
• Renal function tests
• Urinalysis (especially for HSP to assess renal involvement)
• Blood cultures if infection suspected
• Consider skin biopsy for persistent unexplained purpura

Common Pitfalls to Avoid

1. Delayed recognition of meningococcal disease:

   • Half of all children with meningococcal disease are sent home at first presentation 1
   • Early symptoms may be non-specific
   • Absence of fever or headache does not rule out serious infection

2. Misdiagnosis:

   • Confusing non-blanching with blanching rashes
   • Attributing purpura to minor trauma when systemic illness is present
   • Mistaking purpura fulminans for other conditions like TTP 1

3. Inappropriate management:

   • Delaying antibiotics in suspected meningococcal disease
   • Failure to monitor for progression of rash or clinical deterioration
   • Overlooking renal involvement in HSP or vasculitis

Special Considerations

• In children: HSP is the most common vasculitis, typically affecting ages 3-15 years, often following respiratory infection 4
• In adults: Consider medication causes, vasculitis, and malignancy more prominently
• In immunocompromised patients: Lower threshold for aggressive investigation and treatment

Non-blanching purpura represent a critical clinical sign that should prompt immediate assessment and often urgent intervention, particularly when accompanied by systemic symptoms or abnormal vital signs.