[1] Great Ormond St Hosp Sick Children, Dept Gen Surg, London WC1N 3JH, England
[2] Norfolk & Norwich Univ Hosp, Dept Paediat Surg, Norwich, Norfolk, England
[3] Great Ormond St Hosp Sick Children, Dept Haematol & Oncol, London WC1N 3JH, England
[4] Great Ormond St Hosp Sick Children, Dept Histopathol, London WC1N 3JH, England