Isolated Central Nervous System (CNS) Relapse in Paediatric Acute Promyelocytic Leukaemia: A Systematic Review

Extramedullary disease, as a whole, is rare in Acute Promyelocytic Leukaemia (APML). If at all relapse occurs, following sites are involved: Central Nervous System (CNS), skin, testes, mediastinum, gingiva, and ear. Isolated CNS relapses after complete morphological and molecular remission is rarer particularly in children.

To review the literature systematically to find out the incidence of isolated CNS relapse in paediatric APML cases.

A systematic search of major databases (Medline, Pubmed and Google Scholar) was conducted. We included all types of studies that reported about incidence or prevalence of isolated CNS relapse in children upto 18 years of age with APML.

A total of nine studies (with 10 cases of isolated CNS relapse) were included. Majority (70%) was high risk patients, and 60% were ≤six-year-old. Nearly, 50% were having the mean time to relapse <12 months and most (60%) of them were male. The children who died were having shorter time to CNS relapse (around 12 months), and were older (>6 to 18 years).

In the present review, disease in the high-risk group, male sex, younger age (≤six-years-old), and Promyelocytic Leukaemia/Retinoic Acid Receptor Alpha (PML-RARA) detection was found to be associated with isolated CNS relapse in children with APML. Cerebrospinal fluid (CSF) examination along with immunophenotyping and Reverse Transcription polymerase Chain Reaction (RT-PCR) for PML-RARA is required for a definite diagnosis and early treatment of patients to improve overall survival.