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SEER Inquiry System - Report
Produced: 06/14/2025 3:54 AM
Question 20190076
Inquiry Details
References:
ICD-O-3, 21. Rule H
Question:
Primary Site/Brain and CNS: How is primary site coded when the ICD-O-3 provides a sub-site-associated morphology code and the only information available to code primary site for a particular diagnosis indicates a non-specific/not otherwise specified (NOS) site code? See Discussion.
Discussion:
ICD-O-3 Rule H states to use the topography code provided when a topographic site is not stated in the diagnosis. This topography code should be ignored if the tumor arose in another site. For the following brain and central nervous system (CNS) examples, should the suggested sub-site codes be assigned based on the histology, or should the primary sites be coded as C719 (posterior fossa or suprasellar brain) since the only information available was a tumor in these non-specific sites?
Example 1: Resection of a posterior fossa tumor proved medulloblastoma, WNT-activated. Although medulloblastoma has a site-associated code in the ICD-O-3 (C716, cerebellum), the only information available is that this was a posterior fossa tumor (C719).
Example 2: Resection of a suprasellar brain tumor proved pineoblastoma. The pathologist labeled this as a brain tumor, suprasellar. Although pineoblastoma has a site-associated code in the ICD-O-3 (C753, pineal gland), the only information available is that this was a suprasellar brain tumor (C719).
Answer:
If possilbe, ask the physician(s) about the exact site of origin.
If it is not possible to obtain more information, the information in the medical documentation takes priority over ICD-O-3 Rule H, even when that results in a less specific topography code.
