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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.

Assign code 550 (Bladder, NOS excluding mucosa) to EOD Primary Site based on invasion into the bladder with no mention of mucosa. EOD Primary Tumor for cervix, Note 1, instructions are to use the extension information to code primary tumor in preference to a statement of FIGO stage when both are available. TNM staging is closely related to FIGO stage, and the surgical findings of bladder invasion NOS in this case should be used in preference to the statement of T4.

Assign histology as 8072 for non-keratinizing SCC, undifferentiated subtype.

 WHO Classification of Head and Neck Tumors, 5th edition assigns 8072/3 to squamous cell carcinoma, non-keratinizing, NOS in the nasopharynx. As the tumor exhibits a variety of architectural patterns and appearances histologically, they can be further classified as undifferentiated or differentiated subtypes. These subtypes do not change the histology code.

Code the specific histology as stated by the pathologist according to the site-specific instructions in the Solid Tumor Rules. When the histology provides a subtype/variant in addition to the HPV histology codes, code the subtype/variant as it is important to capture this histology as in the example provided. the instruction to code the subtype/variant over 8085 or 8086 applies to the following sites: oropharynx, cervix, vagina, vulva, anus, and penis. A note will be added indicatng this in 2025. 

Per 2024 Cancer PathCHART expert pathologist review, morphology codes 8085/3 and/or 8086/3 are valid and applicable to head and neck, oropharynx, cervix, vagina, vulva, fallopian tube, anus, and penis (reference: Cancer PathCHART: Product Downloads and Timelines). Other coding resources will be updated to reflect these changes in 2025.

For each of your scenarios, the medical record information indicates that the case is not reportable based on physician opinion. Do not abstract these cases.

Remember that the ambiguous terms list is to be used as a last resort. The ideal way to approach abstracting situations when the medical record is not clear is to follow up with the physician. If the physician is not available, the medical record, and any other pertinent reports (e.g., pathology, etc.) should be read closely for the required information. See page 19 in the SEER Manual, https://seer.cancer.gov/manuals/2024/SPCSM_2024_MainDoc.pdf

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.

Abstract as bone metastasis for the first two examples. Abstract as both bone and brain metastasis for the third and fourth examples in the respective Mets at Diagnosis fields based on the description provided.

Assign code 8020/3 when the histologic type specifically includes the term of poorly differentiated, dedifferentiated, undifferentiated, or anaplastic undifferentiated carcinoma along with carcinoma as terms vary depending on the primary site. When the term poorly differentiated is included in the grade section only of the pathology report or only mentions poorly differentiated carcinoma without further substantiation from a pathology report as in examples 1 and 2, do not use code 8020/3.

The histology code 8020/3 and terms may be used for selected primary sites as included in the Solid Tumor Rules, WHO Classification of Tumors series (latest versions), and the Site/Morphology Validation List including

Nasal cavity

Nasopharynx

Salivary glands

Urinary sites

Colon, rectosigmoid, rectum

Esophagus

Stomach

Gallbladder and extrahepatic bile duct

Pancreas

Thyroid

Ovary

Uterine corpus

Vagina

Uterine cervix (also referred to as unclassifiable in WHO Classification of Female Genital Tumors, 5th ed.)

For sites other than those listed, if the diagnosis is poorly differentiated carcinoma, code 8010/3 and poorly differentiated in the grade field. 

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.

In sites other than breast (see Breast Solid Tumor Rules M8/M9), Paget disease with underlying invasive disease is a single primary and the underlying histology is coded. Primary Paget disease of the vulva is uncommon, and we cannot create rules for all possible situations in the Other Sites module. A GYN specific module is in development, and we will look into adding a Paget-related rule. It will differ because Paget in breast is a different situation while Paget in the vulva is always adenocarcinoma.

Paget disease of the vulva is an in-situ adenocarcinoma of vulvar skin with or without an underlying adenocarcinoma (WHO Classification of Female Genital Tumors, 5th ed.). When there is a statement of “underlying” adenocarcinoma, it is a single primary as with Breast Solid Tumor Rule M8.