Myeloid madness: assessing diagnostic inconsistency between the new WHO and ICC schemes for myelodysplastic/myeloproliferative neoplasms.

The classification of haematological neoplasms recently underwent revision, generating two separate schemes-the International Consensus Classification and the fifth edition of the WHO classification. The new division into separate classification systems presents challenges for haematopathologists, haematologists/oncologists and patients. While it is too early to assess the full clinical impact, we sought to identify diagnostic discordance which may arise from applying separate classification schemes in myeloid neoplasia, and particularly in the challenging category of myelodysplastic syndrome/myeloproliferative neoplasms. A review of 64 such cases found 1 case with a significant discrepancy between the WHO and International Consensus Classification systems, and 9 cases with nominal discrepancies. Confusion from the use of conflicting diagnostic terms represents a potential source of patient harm, increased pathologist workload and burnout and erosion of clinician and patient trust.