Post‐Varicella Purpura Fulminans With Extensive Skin Necrosis in a Child

A 5-year-old male with Trisomy 21, presented 7 days after varicella-zoster virus (VZV) infection with rapidly progressive purpura on the lower limbs and gluteal region (Figure 1A). Labs showed thrombocytopenia (64,000/µL), elevated CRP (83.8 mg/L, NR < 5 mg/L), prolonged INR, unmeasurable fibrinogen, and markedly elevated D-dimers (> 150,000 ng/mL, NR < 500 ug/L). Clinical suspicion of disseminated intravascular coagulation (DIC) complicating purpura fulminans (PF) was considered. The patient received IVIG, fibrinogen concentrate, and fresh frozen plasma (FFP), but deteriorated with hypotension, anuria, and progression of skin lesions, requiring PICU admission. Upon PICU admission, severe anemia (Hb 4 g/dL), persistent thrombocytopenia, low fibrinogen (1.2 g/L, NR 1.5–4 g/L), and protein S (< 7.3%, NR 74%–146%) were documented, with no apparent source of bleeding. Protein C and Antithrombin III levels were initially low, consistent with DIC and consumption coagulopathy, but normalized following plasmapheresis. Immunologic workup showed positive anticardiolipin IgG/IgM (76.5/36.8 UQ, NR < 20), and anti-β2-glycoprotein I IgG/IgM (660.1/66.3 UQ, NR < 20), with negativation at 12 weeks follow-up. VVZ PCR in blood was positive, while blood cultures and the remaining etiologic workup, including CMV and HHV-6 PCR, were negative. Treatment included IVIG (Days 1–7), plasmapheresis (Days 1–5), unfractionated heparin (Days 1–11, aPTT-adjusted), later switched to enoxaparin (until Day 42), FFP (Days 5–9 and every 48 h thereafter), and high-dose methylprednisolone with taper over 12 weeks. Protein S levels increased to 41% by PICU discharge on Day 13. Additional therapy included packed red blood cells and platelet transfusions, pain management, nutritional support, and antimicrobials for secondary infections. Complications included bacterial sepsis, fungemia, and iatrogenic adrenal insufficiency. Extensive necrotic skin lesions evolved into full-thickness tissue loss requiring surgical debridement and skin grafting (Figure 1B,C). After 98 days, the patient was discharged, maintained on gabapentin for pain control and corticosteroid taper. PF is a rare thrombotic disorder, typically associated with bacterial sepsis (e.g., pneumococcus, meningococcus, Staphylococcus) or congenital anticoagulant deficiencies. Post-infectious PF, especially following VZV infection, is increasingly recognized in children, and is believed to involve autoimmune mechanisms, with early descriptions demonstrating anti–protein S autoantibodies reducing protein S levels, with spontaneous recovery over weeks to months [1, 2]. More recent reports link post-viral PF with transient antiphospholipid antibodies, which do not appear to correlate with severity, but may exacerbate endothelial injury or coagulopathy in an already primed prothrombotic milieu [3]. This case was severe, requiring PICU admission due to hemorrhagic shock caused by DIC. Children with Trisomy 21 have increased susceptibility to immune dysregulation, potentially predisposing to exaggerated endothelial injury or coagulopathy in a post-viral setting [4]. The transient nature of protein S deficiency is consistent with literature describing acquired, non‑genetic PF forms [5, 6]. Prompt recognition and management—consisting of FFP, anticoagulation, immunomodulatory therapy, and, when necessary, plasmapheresis—are critical to limit progression of thrombosis and necrosis [1, 5, 6]. A multidisciplinary approach involving hematology, infectious diseases, intensive care, and pediatric surgery is crucial to improve outcomes. M.P. prepared and wrote the manuscript. All other authors reviewed the image and manuscript and contributed with critical revisions. The authors wish to extend their deepest appreciation to the nursing staff of the Pediatric Intensive Care Unit and the Burn Unit, as well as to the Nephrology Unit, Acute Pain Service, the medical team of the Nutrition Department, and the nutritionists, for their outstanding professionalism, dedication, and invaluable contributions to the care of this patient. The authors have nothing to report. The authors have nothing to report. Written informed consent for publication of clinical details and photographs was obtained from the patients' legal guardians. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.