Coumarin is an effective treatment for primary lymphoedema, as well as lymphoedema related to breast cancer radiotherapy or surgery. However, its clinical use is limited in several countries due to the possible occurrence of hepatotoxicity, mainly in the form of mild to moderate transaminase elevation. It is worth noting that only a few cases of severe hepatotoxicity have been described in the literature, with no reported cases of liver failure. Data available on coumarin absorption, distribution, metabolism, and excretion have been reviewed, focusing on hepatotoxicity studies carried out in vitro and in vivo. Finally, safety and tolerability data from clinical trials have been thoroughly discussed. Based on these data, coumarin-induced hepatotoxicity is restricted to a small subset of patients, probably due to the activation in these individuals of alternative metabolic pathways involving specific CYP450s isoforms. The aim of this work is to stimulate research to clearly identify patients at risk of developing hepatotoxicity following coumarin treatment. Early identification of this subset of patients could open the possibility of more safely exploiting the therapeutical properties of coumarin, allowing patients suffering from lymphoedema to benefit from the anti-oedematous activity of the treatment.

OBJECTIVE: To define the clinical characteristics, investigations, management and outcomes of lymphoedema in a paediatric cohort.
METHODS: A retrospective chart review of children with lymphoedema seen at two tertiary paediatric hospitals since 1998. Telephone interviews with parents were performed when information was missing. Information recorded included demographic data, features of diagnosis and clinical presentation, symptoms, complications and treatment.
RESULTS: A total of 86 patients with lymphoedema were identified. Eighty cases (93%) were primary and six cases (7%) were secondary. Most were female (60%). Location of swelling was most commonly the lower limbs (94%). There were 13 cases (15%) of genital involvement. Swelling presented in the first 12 months of life in 60% of primary lymphoedema patients. Complications of lymphoedema occurred in 73% of patients. Lymphoscintigraphy was the most common investigation used (65%), followed by ultrasound (57%) and magnetic resonance imaging (MRI) (35%). Eight of the 48 (17%) lymphoscintigraphs produced a false negative result or were inconclusive with a correct diagnosis subsequently made clinically and using MRI. Average time to diagnosis was 9 months. Lymphoedema was managed with compression garments (99%), manual lymph drainage (97%) and multilayered bandaging (68%). Eight patients had an operative procedure as a part of management.
CONCLUSIONS: Primary lymphoedema is more common than secondary lymphoedema in children. Onset tends to be during infancy for both males and females, and the lower limb is typically involved. Causes of secondary lymphoedema are diverse and rare. Diagnosis in children is often delayed but is possible based on history and physical examination alone and when further investigation is necessary MRI is effective.