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Use all information available in the medical record. EOD is a combination of the most precise clinical and pathological documentation of the extent of disease as instructed in the EOD 2018 General Instructions, Extent of Disease section.

EOD 2018 General Instructions, General Coding Instructions section advises to use the medical record documentation to assign EOD when there is a discrepancy between the T, N, M information and the documentation in the medical record. When there is doubt that the documentation in the medical record is complete, code the EOD corresponding to the physician staging. A discrepancy can exist within the medical record when the information in the chart is unclear, incomplete, or conflicting, for example, the TNM staging from pathology differs from the medical oncologist’s TNM staging.

In the scenario provided, use the medical oncologist stage information that takes into account imaging and exam findings. Based on the stage cT4 N3b, assign

EOD Primary Tumor: 400

Extensive skin involvement

WITHOUT a stated diagnosis of inflammatory carcinoma

WITH or WITHOUT dermal lymphatic filtration

EOD Regional Nodes: 600

Internal mammary node(s), ipsilateral, clinically apparent

(On imaging or clinical exam)

WITH axillary (level I, II, or III) lymph node(s), ipsilateral including infraclavicular

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.

Do not report this case of "adenocarcinoma spectrum lesions" based on the information provided in the absence of a more specific diagnosis. Do not report until/unless a definitive diagnosis of malignancy is made. "Adenocarcinoma spectrum lesion" covers a continuum of lung neoplasms from preinvasive lesions (atypical adenomatous hyperplasia and adenocarcinoma in situ) to invasive lesions (minimally invasive adenocarcinoma and invasive adenocarcinoma).

Should additional information become available, report the case and assign the histology code if a more specific histology is confirmed later. Use text fields to record the details.

The example used in Rule M15 of the Urinary Solid Tumor Rules should refer to Table 2. We will update this in the next revision of the Rules.

Conjunctival melanocytic intraepithelial neoplasia (C-MIN) is reportable; therefore, low-grade conjunctival melanocytic intraepithelial lesion (LG-CMIL) with focal high-grade features of the conjunctiva (C690) is reportable, 8720/2.  We will add this to a future edition of the SEER manual.

Abstract this case as a single primary. Code as 8044/3 (small cell carcinoma, hypercalcemic type) listed in the Other Sites Solid Tumor Rules, Table 13. Small cell carcinoma, large cell variant, is a subtype of small cell carcinoma, hypercalcemic type. This table does not include all possible histologies.

WHO Classification of Female Genital Tumors, 5th edition, states: Small cell carcinoma of the ovary, hypercalcemic type, is rare, accounting for < 1% of ovarian tumors. Small cell carcinomas, hypercalcemic type, are usually large, with a mean size of 15 cm (range: 6–26 cm). Large cells are present (in varying numbers) in half of these tumors, which are designated “small cell carcinoma, large cell subtype” if the large cells are predominant (which is rare).

Abstract two primaries using the 2024 Malignant Central Nervous System (CNS) and Peripheral Nerves Solid Tumor Rules, Rule M13. Glioblastoma, IDH-wild-type (9440/3) and astrocytoma, IDH-mutant, grade 4 (9445/3) are on two separate rows in Table 3 of the Malignant CNS and Peripheral Nerves Solid Tumor Rules.

WHO Classification of Central Nervous System, 5th edition, lists the subtypes of glioblastoma, IDH-wild-type as giant cell glioblastoma; gliosarcoma; and epithelioid glioblastoma. The term glioblastoma multiforme is not recommended for glioblastoma, IDH-wildtype in the 5th edition, and lists astrocytoma, IDH-mutant, grade 4 as a subtype of astrocytoma, IDH-mutant.

The CPC ICD-O-3 Site Morphology Validation Lists (SMVLs) designate all tumor site-morphology combinations that are either valid or impossible as determined for the sites reviewed by the Cancer PathCHART initiative. These lists provide information on the Validity Status of specific tumor site and morphology combinations, similar to the way the ICD-O-3 SEER Site/Histology Validation List used to. However, the CPC SMVLs do not include information on the reportability of specific tumor site and morphology combinations. For tumor reportability, you will continue to use the Excel ICD-O-3.2 spreadsheets posted to the NAACCR ICD-O-3 Coding Updates website: https://www.naaccr.org/icdo3/, and the most recent SEER Manual and federal, state, local, and other standard setters' reportability requirements.

Answer updated September 2025:

Abstract a single primary as primary myelofibrosis (9961/3). ET was not reportable in 1998.

Assign Primary Site code C504 based on the location in the upper outer quadrant of the right breast, 10 o’clock, as opposed to code C501, around the areolar complex. The 2024 SEER Manual Breast Coding Guidelines advise that C502 - C505 are generally preferred over C501 when there is no other way to determine the subsite.