CYTOGENETIC AND CLINICOBIOLOGICAL FEATURES OF ACUTE-LEUKEMIA WITH STEM-CELL PHENOTYPE - STUDY OF 9 CASES

Morphologic, immunologic, cytogenetic, and clinical features were stud ied in 9 cases of acute undifferentiated leukemia (AUL). These patient s were unclassifiable by FAB criteria, they were CD34+ and did not exp ress myeloid- or lymphoid-associated antigens (CD13, CD33, CD14, CD15, CD61, CD19, CD10, CD22, CD7, CD2, CD5, CD3). Clonal abnormalities wer e seen in 8 of 9 cases. Del(5q) as the sole anomaly was observed in 3 cases; +13 was the primary change in 3 cases, and isolated trisomy 12 was found in 1 patient. A complex karyotype with trisomy 12q, in assoc iation with del 17p and trisomy 21q was detected in 1 case. One patien t with 5q- relapsed with refractory anemia with excess of blasts; the presence of dysgranulopoiesis and a few blasts with possible monocytoi d morphology in the remaining 2 patients point to a ''myeloid nature'' of these leukemias. Analysis of cytologic features in our 3 patients with +13, in combination with previously reported cases, suggests the occurrence of immature stem cell involvement with limited differentiat ion potential,possibly more along the myeloid than the lymphoid lineag e. The significance of trisomy 12q in this subset of leukemia remains elusive; some clues of minimal differentiation towards the myeloid lin eage in our cases are provided by positivity for the CD117. (c-kit) an tigen and by relapse with acute myeloid leukemia without maturation (M I) in one patient. We conclude that, with presently available diagnost ic techniques, AUL is a rare subset of leukemia, in which cytogenetic changes are confined to a few chromosomes, with prevalent involvement of 5q and of chromosomes 13 and 12. Chromosome findings may be of valu e in clinical practice, especially in those cases with ''myeloid-orien ted'' karyotype. (C) Elsevier Science Inc., 1996