Purpura fulminans

What is purpura fulminans?

Purpura fulminans is a rare, rapidly progressive and often fatal form of acute disseminated intravascular coagulation (DIC). It is marked by intravascular coagulation leading to thrombotic occlusion of small and medium-sized vessels, skin necrosis, cardiovascular shock and multi-organ failure. It is a dermatological and haematological emergency.

Purpura, incipient necrosis, and blistering due to purpura fulminans 

Haemorrhagic necrosis of the skin due to purpura fulminans - the marker lines have been added to assess extension 

Extensive purpura with necrotic blistering over the toes due to purpura fulminans (PF-patient1)

Skin necrosis resulting from purpura fulminans (PF-patient1)

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Who gets purpura fulminans?

Purpura fulminans occurs most often in children, with a bimodal incidence in children aged 1 to 3 years old and adolescents 16 to 18 years old. However, older patients are also susceptible.

What causes purpura fulminans?

Purpura fulminans is caused by a procoagulant shift in haemostatic function. There are three types of purpura fulminans.

• Neonatal purpura fulminans occurs in less than 1:1,000,000 births. It is caused by severe genetic deficiency in Protein C or Protein S. It manifests within hours or days of birth, beginning with retiform purpura and progressing to widespread skin necrosis and visceral involvement. Affected individuals may be born with cerebral thrombosis or retinal vessel occlusion. It is fatal unless treated with protein C concentrate or fresh frozen plasma. Lifelong anticoagulation is then essential. Acquired neonatal purpura fulminans can be triggered by group B streptococcal infection.

• Acute infectious purpura fulminans occurs in the context of severe infections such as sepsis and necrotising fasciitis. Implicated organisms include meningococci, streptococci, Staphylococcus aureus, Haemophilus, and Clostridia. It is caused by direct or indirect inhibition of protein C function by the infective organism or an endothelial inflammatory response.

• Idiopathic (also known as post-infectious or acquired) purpura fulminans presents 7 to 10 days after an infection, due to an autoantibody that inhibits protein S function. The most commonly associated infections include group A streptococcus, varicella zoster, and occasionally human herpes virus 6.

What are the clinical features of purpura fulminans?

Purpura fulminans classically presents as retiform purpura with branched or angular purpuric lesions, particularly over the extremities.

Initially there is cutaneous pain, erythematous macules and petechiae. Lesions then evolve into ecchymoses, then painful indurated purpuric plaques with erythematous borders as the disease evolves. Within 24 to 48 hours, these areas can progress to bullae and vesicles with full-thickness skin necrosis. Purpura fulminans can extend into the subcutaneous tissue, muscle, and bone.

Clinically, patients with purpura fulminans may be septic (with or without shock), or demonstrate meningeal signs.

What are the clinical features of purpura fulminans in varying skin types?

Purpura fulminans has similar clinical features across different skin types. Lighter skin types may exhibit a more purplish-red hue with initial purpuric lesions. In darker skin types, the initial lesions may exhibit brown colouration, however in varying skin types all progress rapidly to haemorrhagic bullae and necrosis.

How is purpura fulminans diagnosed?

Definitive diagnosis is with urgent skin biopsy to exclude differential diagnoses, and blood or tissue culture to identify infectious agents. A full blood count may identify thrombocytopenia. Coagulation studies to identify disseminated intravascular coagulation may demonstrate prolonged coagulation times, decreased fibrinogen, and elevated D-dimer levels. Protein C, protein S, and antithrombin III levels should be ordered to detect deficiencies.

What is the differential diagnosis for purpura fulminans?

• Meningococcal septicaemia
• Disseminated intravascular coagulation
• Vasculitis (eg, drug reaction, infection, autoimmune disease)
• Thrombotic thrombocytopenic purpura (TTP)
• Calciphylaxis
• Necrotising fasciitis
• Toxic shock syndrome
• Warfarin-induced skin necrosis
• Heparin induced thrombocytopenia
• Toxic epidermal necrolysis

What is the treatment for purpura fulminans?

General measures

Prompt recognition of this entity is required to institute timely life-saving measures. Urgent admission to an intensive care unit is paramount.

Specific measures

Multidisciplinary input is required for:

• Targeted antibiotics under the advice of infectious disease physicians
• Anticoagulation (eg, heparin), and replacement of blood products (eg, protein C concentrate or fresh frozen plasma) by haematologist
• Treatment of mucosal membranes – eyes, mouth, genitourinary tract by ophthalmologist, gynaecologist and/or urologist
• Daily wound care dressings, maintenance of moisture balance and surveillance for secondary infection by dermatologist
• Maintenance of nutrition, body temperature regulation, electrolytes, fluid balance and renal function
• Surgical management of affected sites by orthopaedic or plastic surgical teams, including surgical debridement and/or amputation

Wound care:

• Daily dressings using gentle skin handling
• Bland emollients, such as white soft paraffin, dilute emulsifying ointment, or hydrocolloid preparations
• Non-adherent dressings
• Antibacterial dressings, such as silver or povidone-odine impregnated dressings
• Cautious moisture donation to crusted lesions and absorbent dressings to exudative wounds
• Daily surveillance and swabs of skin lesions which may be infected
• Topical steroids for pruritus.

How can purpura fulminans be prevented?

Prevention of purpura fulminans is based on addressing the underlying aetiology of the condition, eg, addressing acquired deficiency of protein C or timely infection treatment to prevent progression. Replacement therapy for patients with severe protein C deficiency may help prevent purpura fulminans from developing.

What is the outcome for purpura fulminans?

Neonatal purpura fulminans is fatal unless treated.

In adults, development of purpura fulminans is a poor prognostic sign.

The mortality rate ranges from 20% to 60% in those with meningococcal disease complicated by purpura fulminans, compared to 15% in uncomplicated cases of meningococcal disease.

Physical therapy for survivors is important to maintain and regain function due to deconditioning, strictures, flexion deformities and amputation.

Death can occur from end-organ damage secondary to thrombosis of small and medium-sized vessels, days to weeks after targeted treatment of the responsible organism.

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