Which ICD-O edition incorporated the WHO classification of hematopoietic and lymphoid neoplasms?

Which ICD-O edition incorporated the WHO classification of hematopoietic and lymphoid neoplasms?

• A. ICD-O second edition
• B. ICD-O fourth edition
• C. ICD-O third edition
• D. ICD-O first edition

Answer: (C)

The edition that integrated the WHO classification of hematopoietic and lymphoid neoplasms is the third edition of ICD-O. This edition was designed to align ICD-O’s morphology codes with the World Health Organization’s hematopoietic/lymphoid classification, bringing the histology categories used by cancer registries into the WHO framework. That means many subtypes defined by WHO were mapped into specific ICD-O morphology codes, enabling more consistent and comparable reporting across registries and over time. Earlier editions used older, separate schemes for hematopoietic and lymphoid neoplasms and did not reflect the WHO classifications, while later updates build on that integration but the first formal alignment with WHO’s hematopoietic/lymphoid classification occurred with the third edition.

The edition that integrated the WHO classification of hematopoietic and lymphoid neoplasms is the third edition of ICD-O. This edition was designed to align ICD-O’s morphology codes with the World Health Organization’s hematopoietic/lymphoid classification, bringing the histology categories used by cancer registries into the WHO framework. That means many subtypes defined by WHO were mapped into specific ICD-O morphology codes, enabling more consistent and comparable reporting across registries and over time.

Earlier editions used older, separate schemes for hematopoietic and lymphoid neoplasms and did not reflect the WHO classifications, while later updates build on that integration but the first formal alignment with WHO’s hematopoietic/lymphoid classification occurred with the third edition.