We describe a case of pediatric acute lymphoblastic leukemia (ALL) with tri
somy 5 as a sole cytogenetic abnormality,. A comparison is made with the tw
o cases of adult acute lymphoblastic leukemia with trisomy 5 in the literat
ure. This rare cytogenetic abnormality may por tend an especially poor prog
nosis in patients with ALL. (C) Elsevier Science Inc., 2000. AII rights res
erved.