- Code grade according to ICD-O-3 (pp. 30-31 and 67).
- Code the grade or differentiation as stated in the final pathologic diagnosis. If the differentiation is not stated in the final pathologic diagnosis, use the information from the microscopic description or comments.
- When the pathology report(s) lists more than one grade of tumor, code to the highest grade, even if the highest grade is only a focus (Rule G, ICD-O-3, p. 21).
- Code the grade or differentiation from the pathologic examination of the primary tumor, not from metastatic sites.
- When there is no tissue diagnosis, it may be possible to establish grade through magnetic resonance imaging (MRI) or positron emission tomography (PET). When available, code grade based on the recorded findings from these imaging reports.
- If the primary site is unknown, code the grade/differentiation as 9 (Unknown).
- Code the grade for in situ lesions if the information is available. If the lesion is both invasive and in situ, code only the invasive portion. If the invasive component grade is unknown, then code 9.
- Do not use "high grade", "low grade", or "intermediate grade" descriptions for lymphomas as a basis for differentiation. These terms are categories in the Working Formulation of Lymphoma Diagnoses and do not relate to grade/differentiation.
- Codes 5-8 define T-cell or B-cell origin for leukemias and lymphomas. T-cell, B-cell, or null cell classifications have precedence over grading or differentiation.
- Do not use the WHO grade to code this data item.
- If no grade is given for astrocytomas, then code 9 (Unknown).
- If no grade is given for glioblastoma multiforme, then code 9 (Unknown).
Although ICD-O-2 and ICD-O-3 Grade/Differentiation are collected as separate items, the only difference between the two editions is that code 8 (NK cells) was added after ICD-O-2 was initially published. They are combined in the PUF, as an output to the ICD-O-2 to ICD-O-3 conversion used for histology and behavior.
|1||Grade I, 1, i||Well differentiated; differentiated, NOS|
|2||Grade II, 2, ii, I/III, or 1/3||Moderately differentiated; moderately well differentiated; intermediate differentiation|
|3||Grade III, 3, iii, II/III, or 2/3||Poorly differentiated|
|4||Grade IV, 4, iv, III/III, or 3/3||Undifferentiated; anaplastic|
|For Lymphomas and Leukemias|
|5||-||T cell; T-precursor|
|6||-||B cell; pre-B; B-precursor|
|7||-||Null cell; non T-non B|
|8||-||NK (natural killer) cell (effective with diagnosis 1/1/95 and after)|
|For Use in All Histologies|
|9||-||Cell type not determined, not stated or not applicable; unknown primaries; high grade dysplasia (adenocarcinoma in situ)|