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SEER Inquiry System - Report
Produced: 11/11/2025 1:34 PM
Question 20180069
Inquiry Details
References:
Solid Tumor Rules. Non-malignant CNS
Question:
Solid Tumor Rules (2018)/Behavior--Brain and CNS: The Behavior coding instructions in the Non-Malignant Central Nervous System (CNS) Equivalent Terms and Definitions section refer to Table 1 for help coding behavior when the other priority order instructions do not apply; however, the behavior cannot be reasonably determined using Table 1 alone for all WHO Grade I neoplasms. Should an additional default, such as the ICD-O-3 or Tables 5 and 6, be used to determine behavior? See Discussion.
Discussion:
Similar to an issue previously submitted SINQ 20180063, Table 1 (WHO Grades of Select CNS Neoplasms) in the Non-Malignant CNS Equivalent Terms and Definitions section states WHO Grade I tumors are always non-malignant. However, this does not mean that the tumors listed in Table 1 as WHO Grade I are always benign (/0). Some tumors listed with a WHO Grade I have a behavior of /1 (borderline) per the ICD-O-3 and/or Tables 5 and 6. The Behavior coding instructions do not currently indicate these are the appropriate sources to use when the pathologist and/or physician do not comment on the behavior of these tumors. In our area, pathologists do not explicitly state the behavior for these tumors; the pathologist only assigns the WHO Grade.
Answer:
There is no way for us to know what behavior to assign WHO grade II tumors when the pathologist does not provide that information. Defaulting to either benign or malignant is incorrect. Please follow back with the pathologist to determine behavior.
The behavior must be non-malignant, meaning /0 or /1, or the tumor is a WHO Grade 1, to be reportable as non-malignant CNS tumor. Refer to Table Instructions under Table 1, WHO Grades of Select CNS Neoplasms that says to use non-malignant CNS rules for all WHO Grade 1 tumors and to use the appropriate rules for WHO Grade 2 tumors
Use ICD-O and all updates if not listed in Table 6 according to non-malignant CNS Histology Rule H3 (for single tumor) and Rule H8 (for multiple tumors) when only one histology is present.
