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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.

The rule order is the same as in the previous MP/H rules. Will keep as is for now.

Assign codes adenocarcinoma in adenomatous polyp (8210), adenocarcinoma in villous adenoma (8261), and (adenocarcinoma in tubulovillous adenocarcinoma (8263) using Other Sites Solid Tumor Rule H12 or Rule H27 as these are specific invasive histology codes. Rule H13 applies to histology codes associated with polyps but associated with a histology term/code other than adenocarcinoma.

Do not report PanIN II. WHO Classification of Digestive Tumors, 5th edition, now categorizes PanIN into two categories, low grade (8148/0) and high grade (8148/2). PanIN grade I and PanIN grade II are categorized as PanIN low grade; PanIN grade III is categorized as PanIN high grade.

We will update the Reportability section of the manual.

Many of these terms are not specified in the codes and definitions in ICD-10-CM. This is because ICD-10-CM does not have the same granularity as ICD-O-3.2. There are a few sites where intraepithelial neoplasia II and/or III are mentioned.

Even though ICD-O-3.2 classifies these as /2 (in-situ), for the intraepithelial neoplasia that are listed in ICD-10-CM, Grade II is designated as benign, while Grade III is designated as in-situ. It is not clear if medical coding will change the Grade II to an in-situ code.

All the in-situ codes (except cervix) are included in the casefinding list. Grade III is included with the in-situ codes; however, there is no guarantee that medical coders will code them as in situ. High grades are coded as in-situ in ICD-10-CM.

For those where there is no specific intraepithelial neoplasia code, the benign codes will cover any benign lesion for that site. This would make for a lot of review using the codes for casefinding. Most of the benign codes were removed from the casefinding list a couple of years ago to make it more manageable. 

Use the casefinding list as a guide for these neoplasias. It is not the most definitive source due to the lack of specificity of ICD-10-CM. It is not possible to map every single histology to a specific code. It is also not known how medical coders across the U.S. are coding these neoplasias. For that reason, pathology should remain the foremost casefinding resource used.

The casefinding team will need to review the prepared list below and determine what codes to add. Any updates will be incorporated in the FY2025 updates (October 2024.)

Code Primary Site to C480 (retroperitoneum). 

Endometrial tissue may "break away” from the uterus and implant throughout the pelvic and abdominal cavities. This can occur in patients who suffer from endometriosis. This tissue remains behind when surgical removal of the uterus is done. Common sites of implantation are colon, peritoneum, retroperitoneum, and bladder. These cells may become malignant. When the uterus is no longer present (patient had surgical removal), code the site where the carcinoma was identified.

The site-morphology combination of C480 and 8380/3 was designated as an unlikely site-morphology combination by the Cancer PathCHART expert pathologist review, as this is a rare type of tumor. Assign a value of 1 in the Over-ride Site/Type [2030] data item in order to pass the Primary Site, Morphology-Type, Beh ICDO3, 2024 (SEER) edit.

If you cannot clarify this with the involved physicians, do not report this case of meningioma based on information provided. There is no indication that the patient was treated or further evaluated for meningioma.

Report clear cell renal cell papillary tumor (CCRCPT), formerly classified as clear cell renal cell papillary carcinoma, and assign code 8323/3 until this new term and code (8323/1) have been adopted by standard setters.

The Kidney Solid Tumor Rules advise to code clear cell papillary renal cell carcinoma as 8323/3. WHO Classification of Tumors of the Urinary System and Male Genital Organs, 4th ed., has reclassified this histology as a /1. This change has not yet been implemented and it remains reportable.

WHO Classification of Urinary and Male Genital Tumors, 5th ed., has since reclassified clear cell papillary renal cell carcinoma as CCRCPT (8323/1). The name change was made because there have been no reports of metastatic events for this indolent tumor. The term clear cell renal cell papillary carcinoma is no longer recommended.

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.

The correct term is diffuse leptomeningeal glioneuronal tumor listed as a synonym in Column 2. 

We will add the term diffuse in Note 2, Column 1 with the 2025 updates. In the meantime, you can add "diffuse" to your pdf version until the update is published.

Report this case as a pituitary tumor (8000/1) based on the information provided. This is the best choice as no specific histology code exists for this generic term “non-Langerhans cell histiocytosis” in ICD-O-3.2, WHO Classification of CNS Tumors, 5th ed., and WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues, 4th ed.

Be sure to double-check the behavior code of the tumor. Histiocytosis can be benign, borderline, or malignant. There was no mention of the behavior so we defaulted to uncertain behavior for this case.