Inherited defects of the protein C anticoagulant system in childhood thrombo-embolism

Genotypic and phenotypic character of Chinese neonates with congenital protein C deficiency: a case report and literature review

Background

Our objective was to study the phenotype of and molecular genetic mechanisms underlying congenital protein C (PC) deficiency in Chinese neonates. We report the case of a neonate who presented 4 h after birth with purpura fulminans of the skin and thrombosis in the kidney. We also carried out a through literature review to study the genotype and phenotype, relevance, diagnosis, management, and prognosis of neonates with congenital PC deficiency in China.

Case presentation and literature review

Following a septic work-up and check of PC and protein S (PS) levels that showed PC deficiency, we investigated the patient’s and her parents’ genotypes. Our patient was found to have a plasma PC level of 0.8%. Molecular testing revealed a compound heterozygous mutation of the PROC gene: From the father, a c._262 G > T p. ASP88Tyr mutation in exon 4; from the mother, a C. 400 + 5G mutation in intron 5 that had been previously reported as likely pathogenic. Both parents were found to have heterozygous mutations for PC deficiency. In China, 5 other cases of congenital PC deficiency in the neonatal period were reported in the literature. In those cases, purpura fulminans and thrombosis were the main symptoms, and homozygous or compound heterozygous mutations of the PROC gene were identified.

Conclusion

Congenital PC deficiency should be ruled out for neonates presenting with purpura fulminans and thrombosis.

Pediatric intracardiac thrombus: a diagnostic and therapeutic dilemma

This case highlights the challenges in treating children with intracardiac thrombosis. We describe a teenager who developed an unsuspected de novo intracardiac thrombus. She was treated initially medically and surgically, but required subsequent surgery to treat a life-threatening recurrence. This case demonstrates an unusual presentation, as well as imaging, diagnostic, and therapeutic dilemmas. More significantly, it emphasizes the importance of a multidisciplinary approach for successful treatment of intracardiac thrombus.

Hematology and Oncology in Critical Illness

This chapter will focus on a variety of hematologic issues pertinent to the care of critically ill children. This is an area of intense research with the pathophysiology underlying these clinical conditions becoming progressively better understood. This improved understanding has resulted in new therapeutic strategies that are being assessed in multicenter clinical trials. The chapter will begin by describing the incidence and pathophysiologic significance of anemia in the pediatric intensive care unit (PICU) providing a differential diagnosis of the many conditions that may present with anemia in this setting. The chapter will next consider disseminated intravascular coagulation (DIC) focusing on the pathophysiology of a condition that has been associated with much morbidity and mortality. The underlying conditions predisposing to DIC will be detailed as well as a number of treatment options that have been implemented in clinical trials. In addition to DIC, thrombocytopenia may be caused by a number of other clinical conditions important to the pediatric critical care provider. The clinical and prognostic significance of thrombocytopenia will be addressed and a focused differential diagnosis will be provided. Thrombotic disorders are becoming increasingly recognized in children and are a particular concern for the pediatric intensivist. The epidemiology of thromboembolism in children will be reviewed focusing on the conditions most commonly associated with these thromboses. Finally, a chapter on hematologic issues in the critically ill child would not be complete without a discussion of sickle cell disease. Acute chest syndrome, one of the most frequent complications of sickle cell disease resulting in the need for intensive care services, will be discussed in detail.

Cardiac, lung, and brain thrombosis in a child with obstructive sleep apnea

A 3-year-old boy with failure to thrive and severe adenotonsillar hypertrophy with a clinical presentation of prolonged obstructive sleep apnea (OSA), was referred to the emergency room due to severe respiratory distress and anasarca. Echocardiography revealed right heart failure, a cystic lesion in the right ventricle and severe pulmonary hypertension. D-dimer was elevated but spiral computerized tomography (CT) and lung scan did not show any perfusion defects. Excision of the cardiac lesion during open-heart surgery, lung biopsy, and adenotonsillectomy were performed. Pathological examination showed an intracadiac organized thrombus and eccentric intimal fibrosis of the pulmonary arteries-which is a pathognomonic of pulmonary arterial microemboli. Brain CT revealed vein thrombosis of the left sigmoid sinus. Blood tests for inherited thrombophilia were normal. Today, 5 years after adenotonsillectomy, the child is normally developed, completely asymptomatic, free of any medications, and has a normal echocardiography. This case report may indicate that prolonged OSA can be a procoagulant state which can cause severe cardiovascular morbidity in children.

Hypercoagulability risk factors in children with minimal change disease and the protective role of protein-C activity

It is believed that thrombotic activity in nephrotic syndrome is due to an imbalance between procoagulant/thrombotic and anticoagulant/antithrombotic factors in plasma. The aim of this study was to investigate the hypercoagulability risk in childhood minimal change disease and to find possible protective mechanisms with respect to hemostasis. Twenty-six children with minimal change disease were enrolled in this study. All patients were evaluated during an attack and on remission. The control group consisted of 33 healthy children. During the attack period, prothrombosis parameters, total lipid, cholesterol, fibrinogen levels and platelet count increased significantly compared to levels in the remission period. This denotes that hyperviscosity increases thrombosis tendency. In the attack period, the significant increase of prothrombin fragments 1 + 2 which shows thrombin formation and thrombin-antithrombin complex which causes prothrombin activation, are an indication of increased thrombosis risk. Five patients with lupus anticoagulant present and 7 patients with, activated protein-C resistance ratios carried an increased thrombosis risk. D-dimer level of fibrinolytic factors significantly increased during the attack period. These findings emphasize the existence of thrombotic activity causing the activation of the fibrinolytic system. The significant increase in protein-C activity in these patients represents one of the protective mechanisms against thrombosis. The decrease in tissue plasminogen activator and antiplasmin indicates the protective role of fibrinolytic activity. Consequently, an increase in the protein-C activity is one of the protective mechanisms. The fibrinolytic system also plays an important role in preventing thrombotic activity in these patients.

Antithrombotic Therapy in Children*

This article about antithrombotic therapy in children is part of the 7th American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh the risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this article are the following. In neonates with venous thromboembolism (VTE), we suggest treatment with either unfractionated heparin or low-molecular-weight heparin (LMWH), or radiographic monitoring and anticoagulation therapy if extension occurs (Grade 2C). We suggest that clinicians not use thrombolytic therapy for treating VTE in neonates, unless there is major vessel occlusion that is causing the critical compromise of organs or limbs (Grade 2C). For children (ie, > 2 months of age) with an initial VTE, we recommend treatment with i.v. heparin or LMWH (Grade 1C+). We suggest continuing anticoagulant therapy for idiopathic thromboembolic events (TEs) for at least 6 months using vitamin K antagonists (target international normalized ratio [INR], 2.5; INR range, 2.0 to 3.0) or alternatively LMWH (Grade 2C). We suggest that clinicians not use thrombolytic therapy routinely for VTE in children (Grade 2C). For neonates and children requiring cardiac catheterization (CC) via an artery, we recommend i.v. heparin prophylaxis (Grade 1A). We suggest the use of heparin doses of 100 to 150 U/kg as a bolus and that further doses may be required in prolonged procedures (both Grade 2 B). For prophylaxis for CC, we recommend against aspirin therapy (Grade 1B). For neonates and children with peripheral arterial catheters in situ, we recommend the administration of low-dose heparin through a catheter, preferably by continuous infusion to prolong the catheter patency (Grade 1A). For children with a peripheral arterial catheter-related TE, we suggest the immediate removal of the catheter (Grade 2C). For prevention of aortic thrombosis secondary to the use of umbilical artery catheters in neonates, we suggest low-dose heparin infusion (1 to 5 U/h) (Grade 2A). In children with Kawasaki disease, we recommend therapy with aspirin in high doses initially (80 to 100 mg/kg/d during the acute phase, for up to 14 days) and then in lower doses (3 to 5 mg/kg/d for > or = 7 weeks) [Grade 1C+], as well as therapy with i.v. gammaglobulin within 10 days of the onset of symptoms (Grade 1A).

Focal nodular hyperplasia of the liver: direct evidence of circulatory disturbances

Focal nodular hyperplasia of the liver is a lesion characterized by a well-circumscribed region of hyperplastic liver parenchyma and contains a stellate fibrous scar. The lesion is thought to be because of liver-cell hyperplasia that is caused by focal circulatory disturbances. We describe here a pediatric case of this lesion that provided direct histopathologic evidence of circulatory disturbances. We identified arterial and portal thrombi, as well as recanalization of arteries in the nodule. Hepatic necrosis was also seen in the lesion. We speculate that thrombosis of the hepatic artery and/or portal vein was the cause of hepatic necrosis and that reperfusion following hepatic arterial recanalization resulted in nodule formation. Although there was no stellate scar present in our case, the presence of bile ductular proliferation at the periphery of the nodule was helpful in distinguishing this lesion from adenoma and hepatocellular carcinoma. The early stage of nodular formation may explain the lack of a stellate scar in our case. The patient was treated earlier with actinomycin D and vincristine following surgical excision of Wilms' tumor. It is possible that such chemotherapy contributed to thrombosis in our case.

Prothrombotic abnormalities in children with venous thromboembolism

PURPOSE

The aim of this study was to determine the frequency of acquired or inherited prothrombotic disorders in a pediatric population with venous thromboembolism (VTE).

PATIENTS AND METHODS

From May 1992 to April 1998, 56 consecutive children with VTE were prospectively studied at a single center.

RESULTS

The median age was 8.4 years (range, 0.1-18 years). There was a male predominance. Fifty (89%) children had thrombosis in the lower venous system. Risk factors were detected in 54 (96%) children. Twenty-one (38%) thrombotic episodes were related to central venous lines. Family history of thrombosis was positive in 13 (23%) patients. In 26 (46%) patients, a prothrombotic disorder was detected. Nine of them had inherited disorders (protein C deficiency, 5 patients; protein S deficiency, 3 patients; Factor V Leiden mutation, 1 patient), and 13 children had acquired disorders (antiphospholipid antibodies, 5 patients; antithrombin deficiency, 8 patients). The remaining four showed combined abnormalities (Factor V Leiden mutation associated with inherited protein S deficiency, 1 patient; acquired antithrombin deficiency, 2 patients and inherited antithrombin deficiency, 1 patient).

CONCLUSIONS

In the series, a high percentage of prothrombotic disorders was detected; thus, a complete hemostatic evaluation should be performed in all of the children with VTE whether the patients have one or more risk factors.

[Antithrombin deficiency and thrombosis in a young child]

BACKGROUND

Thromboses represent a rare event in children and may be due to a deficiency of antithrombin.

CASE REPORT

A 10-year-old boy developed thrombosis due to a congenital quantitative deficiency in antithrombin, confirmed by molecular biology. His father was diagnosed with the same deficiency. The child was first treated with heparin and is now on antivitamin K. He is well 26 months after diagnosis.

CONCLUSION

When a young patient presents with a thrombotic event, a congenital deficiency in one of the inhibitors of coagulation, one of which is antithrombin, should be looked for and the condition treated as soon as possible.

Neonatal symptomatic thromboembolism in Germany: two year survey

AIMS

To determine the incidence of neonatal thromboembolism in Germany.

METHODS

Diagnostic imaging techniques, therapeutic modalities, and short term outcome were evaluated in a prospective nationwide two year case registry study.

RESULTS

The reported incidence of symptomatic neonatal thromboembolism, diagnosed in most cases with Doppler ultrasonography, was 5.1 per 100000 births, with a total of 79 cases registered: renal venous thrombosis (n = 35); venous thrombosis (n = 25); and arterial vascular occlusion (n = 19). Fifty seven of 79 thromboses were associated with additional risk factors (central line n = 25, asphyxia n = 13, septicaemia n = 11, dehydration n = 6, maternal diabetes n = 2, cardiac disease n = 1). Inherited thrombophilia was also diagnosed in seven out of 35 cases investigated. Twenty three children received supportive treatment: 42 received heparin and in 13 neonates thrombolytic agents were administered. Most neonates (91%) survived; seven died.

CONCLUSION

Controlled multicentre studies are needed to obtain more information on treatment efficacy.