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Severe autoimmune protein S deficiency in a boy with idiopathic purpura fulminans
F Bergmann1, P F Hoyer, S V D'Angelo
1Medical School of Hannover, Children's Hospital, Germany.
Insights
A severe streptococcal infection triggered purpura fulminans in an 8-year-old boy, leading to protein S deficiency. Autoimmune factors likely caused this severe deficiency, impacting blood clotting and skin health.
Area of Science:
- Pediatric Hematology
- Immunology
- Infectious Diseases
Background:
- Idiopathic purpura fulminans (IPF) is a rare, severe thrombotic disorder often affecting children.
- IPF is frequently preceded by infections, suggesting a link between infection and the thrombotic event.
Observation:
- An 8-year-old boy developed purpura fulminans and disseminated intravascular coagulation after streptococcal pharyngitis.
- The patient presented with severe protein S deficiency, skin necrosis, and compartment syndrome requiring surgical intervention.
Findings:
- Despite plasma therapy, protein S levels remained critically low for over a month.
- An anti-protein S IgG antibody was detected, correlating with protein S deficiency and resolving as protein S normalized.
Implications:
- Autoimmune protein S deficiency may be a key factor in the pathogenesis of IPF.
- This case highlights the potential role of acquired autoantibodies in severe thrombotic events following infection.
Abstract:
Idiopathic purpura fulminans usually occurs in young children and is frequently preceded by a preparatory viral or bacterial infection. Following a severe streptococcal pharyngitis, an 8-year-old boy developed purpura fulminans with disseminated intravascular coagulation and severe protein S deficiency (total antigen < 0.05 u/ml). Despite generous plasma infusions, skin necrosis progressed rapidly into compartment syndrome which required fasciotomy and skin grafting and resulted in the loss of three digits of the right foot. Total protein S remained low for over a month despite plasma supplementation and complete normalization of protein C levels. A polyclonal anti-protein S IgG was demonstrated in the patient's plasma, which decreased to 25% of baseline titre after 1 month and was undetectable 6 months after purpura fulminans, when plasma protein S had returned to normal. Transient, isolated and severe deficiencies of protein S have been reported in patients with idiopathic purpura fulminans and a previous preparatory infection. Autoimmune protein S deficiency may play a key role in the aetiopathogenesis of idiopathic purpura fulminans.