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Report high grade serous intraepithelial neoplasm of the endometrium. 

Assign 8249/3 for high-grade neuroendocrine tumor of the lung.

WHO Classification of Thoracic Tumors, 5th edition, defines two subtypes of neuroendocrine tumor of the lung, typical carcinoids (8240/3), and atypical carcinoids. WHO assigns typical carcinoid/neuroendocrine tumor grade 1 as 8240/3 and atypical carcinoid/neuroendocrine tumor grade 2 as 8249/3. They are regarded as low-grade and intermediate-grade, respectively. The preferred term for 8249/3 in ICD-O-3.2 is neuroendocrine tumor grade 2, with neuroendocrine tumor grade 3 as a related term. The Lung Solid Tumor Rules assign atypical carcinoid as 8249/3.

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.)

Assign 8013/3 (combined large cell neuroendocrine carcinoma). There are two histologies present: large cell NEC and urothelial. Literature search found primary large cell NEC of the bladder is extremely rare with less than 20 reported cases. This case does not fall into the site-specific rules and given it's raity, a specific rule for this situation was not and will not be added to the Bladder rules. See #1, Example 2, in the general instructions for coding histology.

Stop at the first rule that applies which is M12. Per note 3: When it is unknown/not documented whether the patient had a recurrence, use date of diagnosis to compute the time interval. This means there are two primaries.

There is a genetic syndrome that causes multiple carcinoid tumors in the GI tract, per our GI expert, and they should be treated as new primaries per M12.

SINQ 20110046 describes a unique situation whereby the subject matter expert felt that the occurrence of multiple tumors was due to an unknown underlying condition driving the proliferation of neuroendocrine cells.

Assign histology code, 8077/2 (squamous intraepithelial neoplasia, high grade) for LIN III and for LIN II. ICD-O-3.2 lists squamous intraepithelial neoplasia, grade II and grade III as 8077/2 indicating it is reportable. ICD-O-3.2 does not list every site-specific type of intraepithelial neoplasia. Check the SEER manual for reportable and non-reportable examples.

Abstract two primaries using Urinary Solid Tumor Rules, Rule M12. The histologies include non-invasive papillary urothelial carcinoma (8130/2) and non-invasive micropapillary urothelial carcinoma (8131/3). The two histology codes are listed as subtypes of Papillary urothelial (transitional cell) carcinoma in column 3 of Table 2.

WHO Classification of Urinary and Male Genital Tumors, 5th edition classifies micropapillary urothelial carcinoma as an aggressive subtype of urothelial carcinoma with carcinoma in situ present in more than half of all micropapillary carcinomas.

Rule 7 Note 3 of the Urinary Solid Tumor Rules states that there are no /2 subtypes for urothelial carcinoma with the exception of papillary urothelial carcinoma and applies to multiple occurrences of /2 urothelial carcinoma of the bladder.

Rule 8 applies to 8131/3 and 8120/3.

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.

We will add the same definition for teratoma with malignant transformation found in the ovary table: 9084/3 Teratoma with malignant transformation when a malignant (/3) histology arises in a benign teratoma.

Teratoma with malignant transformation and teratoma with somatic-type malignancy are synonoyms. The term teratoma with somatic-type malignancy is outdated and no longer recommended.

Answer updated September 2025

Per consultation with a male genital and urinary subject matter expert pathologist, if a patient with a previous diagnosis of acinar adenocarcinoma (or a subtype variant of 8140/3) of the prostate was treated with radiation and/or androgen deprivation therapy (ADT, a form of hormonal therapy), the following subsequent diagnoses are NOT a new primary.

• Adenocarcinoma with neuroendocrine differentiation (8574/3)
• Adenosquamous carcinoma (8560/3)
• Small cell carcinoma (8041/3)
• Squamous cell carcinoma (8070/3)

For example, a patient is diagnosed with acinar adenocarcinoma and undergoes hormone therapy. Two years later, the patient is diagnosed with adenosquamous carcinoma. The adenosquamous carcinoma should be considered treatment-related and is not a new primary.