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SEER Inquiry System - Report
Produced: 01/08/2025 2:56 PM
Question 20240011
Inquiry Details
References:
#1: Solid Tumor Rules. Other Sites, May 2023 update
#2: ICD-O-3.2
Question:
Solid Tumor Rules/Histology--Other Sites: Other Sites Table 2 (Mixed and Combination Codes) requires site designations; can sites be added? See Discussion.
Discussion:
There are multiple possible entries (rows) for a tumor with a neuroendocrine component and non-neuroendocrine component, but these rows do not specify which primary sites are applicable. Row 1 (Combined small cell carcinoma, 8045) seems applicable to a prostate primary, but not to a GI primary since GI primaries are now generally referred to as MiNENs (mixed neuroendocrine non-neuroendocrine tumors), but Table 2 does not provide any instructions regarding how to determine the difference between 8045 and 8154 (or 8244).
For SEER Workshop Case 03 (mixed prostate case), many users selected 8154 or 8244 as the mixed histology code per Table 2, but these histology codes are not listed as applicable in Table 3 (Prostate Histologies). Per the WHO Blue Books, these histologies are not listed as applicable to the prostate.
How are registrars to determine the correct mixed code without site designations, especially if they don't have access to the WHO Blue Book or to a pathologist who may be able to clarify the codes?
Answer:
Sites may be added to certain combinations when indicated by ClinCORE review for Cancer PathCHART. Please note some sites were added in the 2024 update as a result of PathCHART review. A newly-formed Solid Tumor Editorial Board and its subgroups are currently working to evaluate the Solid Tumor Manual and make recommendations on ways to improve the structure and formatting of the manual and its content.
Follow the rules and instructions in the Other Sites STRs when assigning combination histology codes.
Histology Coding Rules
Use the Histology Coding Rules when assigning combination codes.
Coding Histology Information
Use this section that includes the mixed histology (Table 2) and site-specific histology tables (Tables 3-23) for one or more histologies within a single tumor. Do not use this section in place of the Histology Coding Rules.
While site-specific histology tables, based on current WHO Classification of Tumors books, have been added to Other Sites STRs, not all site groups have individual histology tables; coding may require the use of ICD-O and updates. The histology tables in Other Sites STRs include additional coding instructions and notes to assign the correct ICD-O code when appropriate.
The tables are not meant to be all-inclusive; rather they are intended to address difficult coding situations to facilitate the assignment of the correct histology code.
Table 2: Mixed and Combination Codes Instructions
Once you have identified the histology terms and have been instructed to use Table 2 by the Histology Coding Rules, compare the terms in the diagnosis to the terms in Column 1. When the terms match, use the combination code listed in Column 2. Use adenocarcinoma mixed subtypes 8255 as a “last resort” code.
