Immunophenotypes of chronic myelomonocytic leukemia (CMML) subtypes by flow cytometry: A comparison of CMML-1 vs CMML-2, myeloproliferative vs dysplastic, de novo vs therapy-related, and CMML-specific cytogenetic risk subtypes

Objectives: We sought to immunophenotype blasts, monocytes, and granulocytes in chronic myelomonocytic leukemias (CMMLs) and compare CMML subtypes, to identify if significant antigen expression differences existed. Methods: Bone marrow blasts, monocytes, and granulocytes from CMML subgroups (n = 30; World Health Organization types 1/2, proliferative/dysplastic, therapy related/de novo, and low/intermediate/high cytogenetic risk) were immunophenotypically compared by flow cytometry with 10 nonneoplastic control marrows. Results: Aberrancies were present in blasts of 26 (87%) of 30 CMMLs (26 diagnostic; four follow-up) and six (60%) of 10 controls (P =. 089), monocytes of 28 (93%) of 30 CMMLs and six (60%) of 10 controls (P =. 026), and granulocytes of eight (28%) of 29 CMMLs and zero of 10 controls (P =. 166). Underexpression of CD14 and CD15 on monocytes was more common in CMMLs compared with controls (P =. 008 and P =. 043). Statistical analysis showed no significant difference in antigen expression between the CMML subgroups on blasts or monocytes; granulocytes demonstrated more common HLA-DR expression in CMML-2 vs CMML-1. Conclusions: These findings confirm heterogeneity within CMML subgroups and find no specific qualitative or quantitative findings characteristic of a subgroup.