Clinicopathological profile of paroxysmal nocturnal haemoglobinuria clone‐positive aplastic anaemia paediatric patients—A single centre study from North India

INTRODUCTION: There is a paucity of literature related to the prevalence of Paroxysmal Nocturnal haemoglobinuria (PNH) clones in paediatric aplastic anaemia (AA) patients. METHODS: We performed a retrospective analysis over a period of 42 months to study the prevalence of PNH clones in paediatric (age less than 18 years) AA cases, using Fluorescein-labelled proaerolysin-based flow cytometric screening and analysed their clinico-pathological features. RESULTS: PNH clone was identified in 100 (33.2%) of the 301 patients screened. These were comprised of 51 cases of non-severe AA, 33 cases of severe AA and 16 cases of very severe AA. The median age was 13 years with an M:F ratio of 2.5:1. The median clone size (taken as the proportion of PNH-positive neutrophils) was 2.15% (range: 0.05%-93.1%). Although a majority of patients (n = 77) had a clone size of less than 10%, a significant proportion (n = 23) did harbour a clone size of more than 10%. Evidence of haemolysis was observed in 3 patients, all of them having a clone size of more than 10%. Interestingly, 1 patient with dural sinus thrombosis harboured a clone size of 1.25% only. Chromosomal breakage analysis was performed in 61 patients, none of which was positive. Complete and partial response to immunosuppressive therapy was found in 55.1% patients (16/29). CONCLUSION: There is a high prevalence of PNH clones in paediatric AA patients, which in a majority of cases are of small clone sizes. The use of immunosuppressive therapy does not show a better outcome as compared to PNH-negative cases.