Changes incytomorphology ofchildhood lymphoblastic leukaemia atthetimeofdisease relapse

Aims-Children in a UnitedKingdom national trial forrelapsed non-Blymphoblastic leukaemia (ALL)hadtheirdiagnosticandrelapse marrowcytomorphology comparedtoseewhatchanges occur during theevolution ofthedisease. Methods-Each relapse slide wasassessed blindly forFrenchAmericanBritish (FAB)typeandothermorphological featuresbyapanelofthreeindependent microscopists without reference toeachother or anydiagnostic material. Diagnostic slides hadbeenassessed bythesamepanel onanearlier occasion. Results-Atotal of134consecutive childrenwasstudied. Six(5%)wereclassified asFAB typeL2 atdiagnosis, compared with18(13%)atrelapse (adifference of 9%/6). Twentytwo(16%)changed their FAB type, 17(13%)fromLItoL2andfive(4%) fromL2toLI.TheFABscorefell atrelapse in34children androsein14,adifference of14%.Cellsizewasthecommonestfeaturetochange(increasing in22anddiminishing innine) followed byprominent nucleoli (appearing in21anddisappearing insix). Fortyfour(33%)children had vacuolated blasts atdiagnosis, compared with48 (36%)atrelapse. Twentyfive changed their vacuole scoresubstantially, 14gaining >10%and11falling <10%. Conclusions-These findings reflect the variability of lymphoblast cytomorphology, butalsoshowa trendforcells to havemoreprominent nucleoli andgreater sizeatrelapse. Factors controlling these features oftheFABtypeareunknown, but theymay simply berelated tothegrowth fraction ofaparticular disease andnotto anylineage specific biological feature. (J7 Clin Pathol 1995;48:1051-1053)