Thromboembolism in children with lymphoma.

Purpose: Cancer is a major underlying disease in children with thromboembolism. However, the epidemiology of thrombosis in children with cancer is largely unknown. We undertook the following study to define the epidemiology and to identify the risk factors predisposing children with lymphoma to thrombosis.
Patients and Methods: We reviewed the medical records of 75 children (<18 years of age) diagnosed with lymphoma from January 1990-December 2004.
Results: Nine of 75 patients (12%, 95% CI; 5.6-21.6%) were diagnosed with a total of 16 thrombotic events. Twelve of 16 (75%) events were venous thrombosis; 11 were related to the central venous line. The prevalence of pulmonary embolism was 2.6%. Nine of 51 (17.6%) patients with mediastinal lymphadenopathy developed thrombosis compared to none of 21 patients without mediastinal lymphadenopathy (Z=3.31, p=0.001, 95%CI; 7.2-28.1%). Older children and children with advanced stage disease were at higher, but statistically non-significant risk of thrombosis. There was no effect of gender, lymphoma type, or B-symptoms on the occurrence of thrombosis. Four of 9 patients (44%) experienced recurrent clots and 3 (33.3%) patients had post-thrombotic syndrome. Children with thrombosis had a higher rate of adverse events compared to those without thrombosis (41% vs. 21.2%, p=0.126).
Conclusion: Thrombosis is a frequent complication in children with lymphoma with over a 40% recurrence rate and significant morbidity. Children with a mediastinal mass were at significantly increased risk of thrombosis. Larger prospective studies are required to confirm these findings and to identify children at an increased risk for the development of thrombosis.