2018 ICD-O-3 Histology Code & Behavior Update


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Guidelines for the 2018 ICD-O-3 Update have been created and can be downloaded from NAACCR.

ICD-O-3 Codes come from World Health Organization (WHO) International Histology Classification of Tumors (Blue Books) and International Agency for Research on Cancer (IARC).  Since the ICD-O-3 codes update in 2011, WHO has continued to publish updates to the WHO Blue Book Series. When a new Blue Book is published, the terminology and codes are introduced into contemporary pathology terminology to be used in pathology reports.  Malignant diagnoses from these books that find their way into cancer registries may not be listed in ICD-O-3, which is the standard references for reportable conditions. This is an issue if there are no histology codes available for the registrar to use. Sometimes a new code can be crosswalked to an existing code until the new code is implemented.

ICD-O-4 is not expected anytime soon

Check the 2018 ICD-O-3 Update Table FIRST to determine if the histology is listed.  If the histology is not included in the update then review ICD-O-3 and/or Hematopoietic & Lymphoid Database and/or Solid Tumor (MP/H) rules

Currently in ICD-O-3 when a topography is listed in parentheses next to the morphology term it indicates morphology is most common to that site.  It may occur in other sites as well.  Many of the new codes, terms, and behaviors listed in the update are site-specific and do not apply to all sites.  If the code or term is specific to a site, the topographical site code will be listed in BOLD font after the term

What’s New for 2018?

  • New ICD-O codes/terms
    • 36 New codes and associated terms
    • 11 previously approved but not implemented (2014 Update crosswalk)
  • Behavior code changes & associated terms
  • 19 existing ICD-O-3 codes have had a change in behavior codes
  • New associated terms
  • New terms for existing ICD-O-3 codes
  • 114 new associated terms
  • Some ICD-O-3 codes have more than one new term
  • Some new terms are site specific
  • No old terms made obsolete

The 2018 ICD-O-3 Update Table is in PDF and Excel formats

  • All changes will be consolidated into a single table
  • Numerical order by ICD-O-3 code
  • Previously approved but never implemented ICD-O-3 codes will be included in the table



  • 8250/3
  • Lepidic adenocarcinoma (C34._)
  • Lepidic predominant adenocarcinoma (C34._)
  • 8253/3
  • Invasive mucinous adenocarcinoma (C34._) Dx prior to 01/01/2018 use code 8480
  • 8254/3
  • Mixed invasive mucinous and nonmucinous adenocarcinoma (C34._)
  • WHO 4th Ed Lung:  Proposed discontinuing the terms bronchioloalveolar carcinoma or BAC
  • 8551/3 Acinar adenocarcinoma (LUNG PRIMARIES ONLY)
  • WHO 4th Ed Lung has proposed code 8551/3 for acinar adenocarcinoma of the lung rather than use the existing code 8550/3 which is also acinar adenocarcinoma
  • Specific criteria are needed for diagnosis of acinar in lung
  • Cases diagnosed prior to 01/01/2018 use code 8550/3
  • 8140/3 Acinar adenocarcinoma of prostate (61.9)
  • WHO 4th Ed Tumors of Male Genital Organs has proposed the term “acinar adenocarcinoma for primary prostate tumors added as alternate term for 8140/3 adenocarcinoma NOS

The ICD-O Work Group will address changes proposed in the future Blue Book updates to work toward solutions for a consolidated ICD-O manual. Questions concerning the 2018 ICD-O-3 Update can be submitted through Ask A SEER Registrar:  https://seer.cancer.gov/registrars/contact.html