Distinction between aleukaemic prodrome of childhood acute lymphoblastic leukaemia and aplastic anaemia.

AIMS To document the features of the so-called aplastic presentation of childhood acute lymphoblastic leukaemia (ALL) and to determine whether this prodrome can be distinguished from aplasia. METHODS The peripheral blood and bone marrow appearances of all cases of childhood ALL presenting in one health region of England in 13 years and eight months were reviewed. All cases presenting with cytopenia without circulating blasts and marrow aspirates with no infiltrate of blasts were studied in detail. RESULTS Four of 305 (1.3%) children presented in this way. All four had reticulin fibrosis and increased cellularity in all or part of the marrow biopsy specimen. All were girls. Three had common and one surface membrane immunoglobulin positive ALL. Reassessment of this prodrome, by combining the features of four previously reported series of similar cases with the present one, highlighted the female preponderance (19 of 22 cases), bone marrow fibrosis (10 of 11 evaluable cases), prominent bone marrow lymphocytes (14 of 22 cases) and temporary recovery (all 12 evaluable cases). Six of 14 evaluable cases had bone marrow biopsy specimen appearances of apparently uniform hypocellularity, but only one of these did not have fibrosis. CONCLUSIONS If, in addition to an aspirate, a bone marrow trephine biopsy is carried out the prodrome can be distinguished from aplasia in most cases. The similarity of this prodrome to aplastic anaemia is merely superficial. Clinicians and morphologists may fail to appreciate the implications of this mode of presentation if the term "aplastic" continues to be used to describe this aleukaemic prodrome of ALL.