CD34‐positive acute promyelocytic leukemia is associated with leukocytosis, microgranular/hypogranular morphology, expression of CD2 and bcr3 isoform

• Published in: American journal of hematology 2001-05, Vol.67 (1), p.34-41
• Main Authors: Foley, R., Soamboonsrup, P., Carter, R.F., Benger, A., Meyer, R., Walker, I., Wan, Y., Patterson, W., Orzel, A., Sunisloe, L., Leber, B., Neame, P.B.
• Format: Article
• Language: English
• Subjects: Actuarial Analysis; Adolescent; Adult; Aged; all‐trans‐retinoic acid; Antigens, CD34 - analysis; APL; Biological and medical sciences; CD2; CD2 Antigens - biosynthesis; CD34; Cohort Studies; Female; Granulocytes - pathology; Hematologic and hematopoietic diseases; Humans; Immunophenotyping; Karyotyping; Leukemia, Promyelocytic, Acute - diagnosis; Leukemia, Promyelocytic, Acute - immunology; Leukemia, Promyelocytic, Acute - pathology; Leukemias. Malignant lymphomas. Malignant reticulosis. Myelofibrosis; Leukocytosis - pathology; Male; Medical sciences; Middle Aged; Neoplasm Proteins; Oncogene Proteins - biosynthesis; Oncogene Proteins, Fusion; PML‐RARα; Prognosis; Protein Isoforms - biosynthesis; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcr; Survival Rate; Translocation, Genetic
• ISSN: 0361-8609; 1096-8652
• DOI: 10.1002/ajh.1073

Acute promyelocytic leukemia (APL) has a favorable prognosis. Current therapy includes chemotherapy used in combination with all‐trans‐retinoic acid (ATRA). Although the differentiating effects of ATRA on promyelocytes have been well established, in vitro studies have shown that less‐differentiated APL blasts (CD34+) demonstrate a variable responsiveness to ATRA. To assess the clinical relevance of this finding, we analyzed a cohort of 38 patients with t(15;17) and/or PML‐RARα APL to determine the incidence and laboratory features of CD34+ APL. Thirty‐two percent (12/38) of cases were CD34+. There was a difference in WBC at presentation between CD34+ and CD34− cases (34.6 ± 9.2, mean ± standard error vs. 5.4 ± 2.0, P = 0.009). Patients with CD34+ APL demonstrated a micro/hypogranular phenotype (75%) (P = 0.001), co‐expression of CD2+ (83%) (P = 0.001), and the bcr3 isoform (100%) (P = 0.017). In contrast, CD34− cases demonstrated hypergranular morphology (65%), CD2+ (15%), and the bcr1 isoform (50%). A high presenting WBC count (\G10 × 109/L) was associated with an inferior overall survival (Log rank = 0.0047). Patients with CD34+ APL demonstrated an incidence of early mortality of 50%. Despite a marked correlation between CD34 positivity and increased WBC count, overall survival of CD34+ and CD34− cases did not differ significantly in our small cohort. Immunophenotypic analysis for CD34 expression should be included in future large APL trials to determine if detection of CD34+ blasts represents an independent adverse prognostic factor. Am. J. Hematol. 67:34–41, 2001. © 2001 Wiley‐Liss, Inc.