Paroxysmal Nocturnal Haemoglobinuria From the Prespective of Paediatric Haematologists

Paroxysmal nocturnal haemoglobinuria (PNH) is very rare in children. The review of the literature shows some peculiarities of paediatric age: high incidence of bone marrow failure at diagnosis, dark urines uncommon, diagnosis often delayed. The thrombosis incidence is variable in the different reports, but in general lower than in adults. The presence of glycosil phosphatidyl-inositol (GPI)-negative populations in acquired aplastic anaemia (AA) at diagnosis has been correlated with a favourable response to immune-suppressive therapy (IST) in adults, whereas the literature data in children are discordant. The Authors carried out two studies on respectively 24 and 85 paediatric patients with AA. By high resolution flow cytometry the presence of a GPI-negative population was observed respectively in 53% and 41% at diagnosis of AA, without correlation with the response to IST. In some cases, the appearance of a GPI-negative population in patients previously GPI-positive was associated to cyclosporine tapering or to AA relapse. Flow cytometry follow up is suggested for the early detection of GPI-negative clones in AA in IST, but larger studies are needed to define their correlation with immune-mediated damage and with IST response.