International classification of diseases / oncology, morphological part for typing of benign and malignant tumors. The morphology axis provides six-digit codes ranging from 8000/0 to 9989/3. The first four digits indicate the specific histological term, i.e. morphology (8000 through 9992).
In developing the previous editions and the present edition of ICD-O, a particular effort was made to use the nomenclature appearing in the World Health Organization
International Histological Classification of Tumours series (WHO “Blue Books”)
7
. This series covers all the principal sites of cancer and includes the morphology codes of ICD-O for each neoplasm. All new histological classifications or modifications have been made by the WHO / IARC in so-called "Blue Books" by 2011 are listed on-line:
http://codes.iarc.fr/changes.php.
The fifth digit after a slash (/) is the behavior code, which indicates whether a tumor is malignant, benign, in situ, or uncertain (whether benign or malignant).
A separate, 6th, one-digit code may also be given for histologic 4-tiered grading (differentiation) or for the cell type in lymphatic neoplasia.
The fifth and the sixth digit are coded separately in value sets 1.3.6.1.4.1.19376.1.3.11.34 and 1.3.6.1.4.1.19376.1.3.11.35