Congenital protein C (PC) deficiency is one type of hereditary thrombosis. Patients with hereditary thrombosis are at high risk for thrombosis in the perioperative period, but a standard management strategy has not been established. Here we report a case of perioperative management of a fracture in a child with homozygous congenital PC deficiency. The patient was a 3-year-old boy who was diagnosed with congenital PC deficiency at birth. He sustained a traumatic supracondylar fracture of the right humerus and underwent emergency surgery. To prepare for open surgery for fixation of the fracture, warfarin was discontinued, and an activated PC (APC) concentrate was used in combination with vitamin K antagonism. However, warfarin was administered during the scheduled nail extraction because the operation was minimally invasive. No thrombotic or bleeding complications occurred in either operation. In emergency surgery in patients with congenital PC deficiency, the combination of vitamin K and APC concentrate is considered a maintenance option for PC deficiency. Postoperative PT-INR control was difficult in our patient due to the administration of vitamin K and withdrawal of warfarin, and this issue must be addressed in the future. Further case experience is desirable to standardize perioperative management.

BACKGROUND: Purpura fulminans (PF) is a hematological emergency that can be caused by severe congenital protein C (PC) deficiency. It has been rarely reported in the Chinese population. We aimed to characterize the clinical and genetic features of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF.
METHODS: Twelve pediatric patients were diagnosed with severe congenital PC deficiency with PF, which was diagnosed based on our hospital records and previous reports from 1988 to July 2021 in China. We evaluated the clinical and genetic features of these patients.
RESULTS: Nine patients (9/12, 75%) had onsets that were observed within the first 48 h after birth. Six patients had a family history of thromboembolism. There was no consanguinity. Other symptoms were intracranial thrombosis or hemorrhage (4, 33.3%), ocular lesions (2, 16.7%), gastrointestinal hemorrhage (2, 16.7%) and kidney infarction before birth (1, 8.3%). All but one of the patients (one case not detected) had a plasma PC activity of <10%. The genetic study indicated that in the eight patients with inherited PC deficiency, two were homozygous, five were compound heterozygous and one was heterozygous for PC deficiency.
CONCLUSIONS: This is the first and largest case series of Chinese pediatric patients with severe congenital PC deficiency who first presented with PF. It has been shown that treatment with both fresh frozen plasma and anticoagulants is recommended when PC concentrate is not easily available, especially in developing countries.

Perioperative management of severe congenital protein C deficiency remains unestablished. This deficiency is often treated with anticoagulants, such as warfarin. Although anticoagulants need to be perioperatively discontinued, there are few methods for the management of such patients. We adopted a method for administering prothrombin complex concentrates (PCC), which includes intermittent administration of inactive protein C (PPSB-HT), and examined its outcome as a perioperative management approach for severe congenital protein C deficiency. Three patients underwent our perioperative management six times. We monitored activity levels of protein C, factor IX, and so forth. These patients could be perioperatively managed with PCC treatment.

Homozygous/compound heterozygous forms of congenital protein C deficiency are often associated with severe antenatal and postnatal thrombotic or hemorrhagic complications. Protein C deficiency frequently leads to severe adverse outcomes like blindness and neurodevelopmental delay in children and may even lead to death. The most widely used long-term postnatal treatment consists of oral anticoagulation with vitamin K antagonists (e.g., warfarin), which is supplemented with protein C concentrate in acute phases. Subcutaneous infusions have been described in infants mostly from 2 months of age after severe postnatal thrombosis, but not in newborns or premature infants without thromboembolism. We report the first case of a compound heterozygous protein C-deficient preterm infant, born at 31+5 weeks of gestation to parents with heterozygous protein C deficiency (protein C activity 0.9% at birth). We focus on both prenatal and perinatal management including antithrombotic treatment during pregnancy, the cesarean section, and continuous postnatal intravenous and consecutive subcutaneous therapy with protein C concentrate followed by a change of therapy to direct oral anticoagulants (DOACs) (apixaban). We report successful home treatment with subcutaneous protein C concentrate substitution overnight (target protein C activity >25%) without complication up to 12.5 years of age. We propose that early planned cesarean section at 32 or preferably 34 weeks of gestation limits potential maternal side effects of anticoagulation with vitamin K antagonists and reduces fetal thromboembolic complications during late pregnancy. Intravenously administered protein C and early switch to subcutaneous infusions (reaching about 3 kg body weight) resulted in sufficient protein C activity and has guaranteed an excellent quality of life without any history of thrombosis for 13 years now. In older children with protein C deficiency, as in our case, DOACs could be a new therapeutic option.

We reported a 31-year-old man with recurrent cerebral venous thrombosis caused by congenital protein C deficiency. He was diagnosed with cerebral venous thrombosis before 7 months. He was transferred to our hospital with numbness of right hand and right side of face, and dysarthria. The blood examination showed that his protein C antigen level and protein C activity were decreased than the lower limits of normal. Brain magnetic resonance venography showed poor visualization of the superior sagittal sinus and cortical veins. Genetic analysis revealed a single-base substitution (C>T) at the codon 811 (Arg to Trp) in the 9th exon portion of the protein C gene. Taking those results, he was diagnosed with recurrent cerebral venous thrombosis due to congenital protein C deficiency. Cerebral venous sinus thrombosis that occurred in the absence of an incidents of disease or internal history when there is a juvenile onset, a past history, or a family history, is suspected of congenital thrombophilia and needs blood tests and genetic tests.

Protein C is one of the major inhibitors of the coagulation system that downregulate thrombin generation. Severe congenital protein C deficiency leads to a hypercoagulability state that usually presents at birth with purpura fulminans and/or severe venous and arterial thrombosis. Recurrent thrombotic events are commonly seen. From the 1990\'s, several virus-inactivated human protein C concentrates have been developed. These concentrates currently constitute the therapy of choice for the treatment and prevention of clinical manifestations of severe congenital protein C deficiency. This review summarizes the available information on the use of human protein C concentrates in patients with severe congenital protein C deficiency.