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Assign histology code 8254/3 (mixed invasive mucinous and non-mucinous adenocarcinoma) to this lung tumor using Lung Solid Tumor Rules, Rule H4. This is a new code/term approved by IARC/WHO for ICD-O. Rule H4 instructs one to code the histology when only one histology is present. In this case, the pathologist indicates the tumor is mixed mucinous and non-mucinous histologies. The non-mucinous carcinoma that is seen in this mixed histology may be identified as: Adenocarcinoma in situ, minimally invasive adenocarcinoma, or lepidic predominant adenocarcinoma. In this case it is lepidic predominant adenocarcinoma. Lepidic is a recognized histology in lung. It is not unusual for the pathologist to indicate mixed non-muncinous and mucinous adenocarcinoma AND also list the non-mucinous subytpe. It is important to capture both mucinous and non-mucinous histologies which drives treatment, etc. 

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.

Do not report neuroendocrine tumorlet of lung and non-lung sites. Microcarcinoid and carcinoid tumors are reportable.

Tumorlet is a tumor of neuroendocrine differentiation, defined by size < 5 mm in diameter, mitotic count < 2 mitoses/2 mm², and absence of necrosis. Microcarcinoid is a designation for neuroendocrine tumors when they are less than 0.5 cm. in size. The term "tumorlet" is used in a number of other settings, referring to small tumors (usually < 0.5 cm), and does not necessarily mean carcinoid tumor.

The term microcarcinoid tumor is not equivalent to neuroendocrine tumorlet.

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.

Do not report angiomyxoma. ICD-O-3.2 assigns 8841/0 to this benign tumor. This includes superficial and deep (aggressive) angiomyxoma.

Report VIN II. The 2024 SEER Manual lists this as a separate diagnosis in the Reportability section under Malignant Histologies 1.a.x. 

Report this case of leukemia cutis and code to bone marrow (C421) and leukemia NOS (9800/3) based on the information provided. Update the abstract if new information becomes available.

Leukemia cutis is the rare infiltration of neoplastic leukocytes into the epidermis, dermis, or subcutis from an existing leukemia that results in clinically identifiable cutaneous lesions. Leukemia cutis may precede, follow, or occur concurrently with the diagnosis of systemic leukemia. It is an advanced phase of the leukemia having a poor prognosis that also strongly correlates with additional sites of extramedullary involvement. This can alter the appropriate treatment regimen for a patient. It is a type of "metastasis" or spread of the leukemia cells. The "conventional" definition for leukemia cutis is the infiltration of skin from a bone marrow primary. It is most often diagnosed via skin biopsy—punch, shave, etc., utilizing IHC/biomarker testing and is commonly associated with CMML and acute myeloid leukemia (AML). As such, it a reportable condition especially when preceding a confirmed systemic leukemia diagnosis. In this situation, the diagnosis date would be the date of the positive leukemia cutis skin bx—punch, shave, etc. The case should be coded to C421; 9800/3 Leukemia NOS until the official systemic leukemia diagnosis is rendered. If possible, follow back should be conducted to determine the specific systemic leukemia histology (CMML; AML) and the treatment received. If the leukemia cutis follows or occurs concurrently with the diagnosis of a systemic leukemia, it is NOT a separate primary but merely an advanced stage of the systemic leukemia diagnosis.

The CPC Validity Status of the site morphology combinations of C569/8441/3 and C569/8441/2 was revised from Valid to Unlikely with the latest release of the Version v24A Edits Metafile. As a result, this site and morphology combination will now require an over-ride flag to be set.

Code as 8461/3 (high-grade serous carcinoma) or 8460/3 (low-grade serous carcinoma) if at all possible. Use 8441/3 (serous carcinoma, NOS) only if it cannot be distinguished as low grade or high grade. The codes for high-grade serous carcinoma and low-grade serous carcinoma are relatively new. High-grade serous carcinoma and low-grade serous carcinoma are very different tumors and pathologists should state whether it is high grade or low grade. Please make every attempt to use the newer codes. If unable to determine high gade versus low grade, assign 8441/3 and override the edit.

The files on the CPC website are currently being updated, and CPC*Search will be updated to reflect the changes sometime this Fall.

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.)

Abstract a single primary for this scenario based on Urinary Sites STRs. 

10/2017 and 12/2017 bladder diagnoses:  Single primary (Rule M15:  Abstract a single primary when synchronous, separate/non-contiguous tumors are on the same row in Table 2 in the Equivalent Terms and Definitions). This interval is not indicative of recurrence as there is no clinically disease free period on follow-up.

Use the Multiple Primary Rules as written to determine whether a subsequent tumor is a new primary or a recurrence as stated in the General Instructions. The only exception is when a pathologist compares slides from the subsequent tumor to the “original” tumor and documents the subsequent tumor is a recurrence of the previous primary. Never code multiple primaries based only on a physician’s statement of “recurrence” or “recurrent.”

 12/2017 (bladder) and 4/2018 diagnoses (renal pelvis):  Single primary (Rule M11:  Abstract a single primary when there are urothelial carcinomas in multiple urinary organs; behavior is irrelevant.)