Compound heterozygous congenital protein C deficiency: a challenging management with recurrent purpura fulminans treated with protein C concentrations.

A female newborn was transferred to the hospital due to progressive necrotic skin lesions. She was born full-term with an average birth weight and no prenatal or perinatal problems. She developed the first purplish skin lesion on her left buttock since postnatal day 1. She was initially treated with antibiotics under the impression of early-onset neonatal sepsis; however, her lesions worsened and rapidly progressed. The protein C chromogenic activity was remarkably decreased at below 10%, similar to a protein C antigen level below 1%, highly suggestive of severe congenital protein C deficiency. Molecular analysis revealed compound heterozygous likely pathogenic variants in the protein C gene. After the diagnosis, fresh frozen plasma (FFP) transfusions every 8 hours until the patient was stabilized and therapeutic low-molecular-weight heparin was started. She developed complications related to FFP administration, such as acute kidney injury, hypertension and proteinuria, during the interim period, awaiting the initiation of protein C concentrate replacement therapy.