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The 2024 Solid Tumor Rules, Table 5: Tumors of the Oropharynx, Base of Tongue, Tonsils, Adenoids contain notes that say beginning 1/1/2022, keratinizing or non-keratinizing SCCs, HPV positive or HPV negative, are coded 8085 or 8086, respectively, for sites listed in the Head and Neck Solid Tumor Rules, Table 5 only.

Table 5 introductory section also states for cases diagnosed 1/1/2023 forward: “When the diagnosis is a subtype/variant of squamous cell carcinoma and HPV status is also noted, code the subtype/variant.” This latter instruction is also included in Other Sites Table 23 (Penis and Scrotum Histologies) as a “Penis Coding Note.”

Do these instructions ONLY apply to sites on those tables (and only to Penis or to Scrotum also in Table 23)? How should we code HPV-related keratinizing/non-keratinizing or other subtype/variant SCCs, for sites NOT on those tables, given the fact that only the more common histologies are listed in the Solid Tumor tables?  For example, we recently reviewed a case with HPV-positive basaloid squamous cell carcinoma of the anus (C21.0).

The Solid Tumor Rules state that for cases diagnosed in 2022 and forward, p16 testing CAN be used to assign histology code 8085 (squamous cell carcinoma, HPV positive). The rules also state that for cases diagnosed prior to 1/1/2022, code 8085 MUST be based on ISH testing and not p16. ISH testing is not specifically addressed for 2022+ cases, but are we correct in assuming it can still be used as the basis for 8085?

Multiple CAnswer Forum posts and the AJCC 8th edition Head and Neck staging webinar indicate that the correct chapter/registry staging schema in this situation is determined ONLY by p16 results - not ISH testing, and therefore the Schema Discriminator 2 SSDI should be coded as 1 – p16 negative, regardless of ISH results.

While we understand that histology codes should not be changed based on staging criteria, there is a SEER/NAACCR edit, “Schema Discriminator 2, Head and Neck, Histology (NAACCR)” tag number N6802, that will not allow coding 8085 if Schema Discriminator 2 is coded as 1 (p16 negative). The edit does seem to be correctly enforcing the AJCC guidelines for choosing the staging schema, based on the sources noted above. Do the Solid Tumor or Site-Specific Data Items (SSDI) guidelines need to be modified for this situation?

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.

Note: The same row means the tumors are

• The same histology (same four-digit ICD-O code) OR

• One is the preferred term (column 1) and the other is a synonym for the preferred term (column 2) OR

• A NOS (column 1/column 2) and the other is a subtype/variant of that NOS (column 3) OR

• A NOS histology in column 3 with an indented subtype/variant

Example: TURBT shows invasive papillary urothelial carcinoma 8130/3 and CIS/in situ urothelial carcinoma 8120/2. Abstract a single primary. Papillary urothelial carcinoma and urothelial carcinoma are on the same row in Table 3.

Example: 12/2023 Breast lumpectomy final diagnosis is Invasive ductal carcinoma, lymphoepithelioma-like carcinoma type. This is a single tumor with no in situ carcinoma present.

Lymphoepithelioma-like carcinoma is not listed as a subtype/variant or synonym for breast carcinoma in the Solid Tumor Rules histology tables.

An 80-year-old post-menopausal female (status post hysterectomy for benign reasons) presents with a retroperitoneal mass on imaging. The pre-operative imaging shows the cervix and uterus are absent. Patient undergoes a robotic left salpingo-oophorectomy with biopsy of the retroperitoneal mass.

Example: Patient had a 2023 nasopharyngeal mass biopsy showing “Nasopharyngeal non-keratinizing squamous cell carcinoma, undifferentiated type.” 

The Head and Neck Solid Tumor Rules (STRs) do not include an H Rule that instructs us how to code histology when there are two subtypes/variants present for a head and neck primary, nor does the STR define undifferentiated carcinoma as a subtype/variant for 8072.

The WHO Classification of Head and Neck Tumors states non-keratinizing nasopharyngeal carcinoma (non-keratinizing squamous cell carcinoma (SCC) is the most common subtype for nasopharyngeal ca, but that non-keratinizing can be subdivided into undifferentiated and differentiated subtypes.

Should histology be 8020 (undifferentiated carcinoma) or 8072 (non-keratinizing SCC)?

The patient had neoadjuvant chemotherapy (Carboplatin and Paclitaxel) concurrent with radiation per the managing physician. The physician stated the patient completed the neoadjuvant therapy; however, it was also noted that patient completed five cycles of chemotherapy, but the sixth cycle was held due to neutropenia.

The SEER Manual does not address how to code Neoadjuvant Therapy when the patient completed almost all the planned neoadjuvant therapy. It seems inappropriate to code Neoadjuvant Therapy as 2 (Started but not completed) simply because the patient did not have one cycle of chemotherapy but is otherwise felt to have completed neoadjuvant therapy per the managing physician. Does the managing physician’s statement of “completion” impact how this scenario is coded?

Malignant Central Nervous System (CNS) Rule M5 instructs us to abstract a single primary (as malignant) when a single tumor is originally diagnosed as non-malignant, the “First course treatment was active surveillance (no tumor resection),” and the subsequent resection pathology is malignant.

This patient’s first course of treatment was not active surveillance. While the patient did not have first course tumor resection, the tumor was treated with Cabergoline.

Should Rule M5 apply because there was no tumor resection? If so, should Rule M5 clearly state no tumor resection is the criteria (not active surveillance)?

SINQ 20230023 does indicate a PitNET diagnosis following a diagnosis of pituitary adenoma does not fall into standard rules, but in the previous SINQ the first course treatment was a partial resection.

It is unclear whether other types of treatment could result in a new malignant PitNET, following a previously treated non-malignant pituitary tumor.

The term “poorly differentiated carcinoma (NOS)” is listed as related to “undifferentiated carcinoma (NOS)” in the ICD-O 3.2. It is also listed in the Solid Tumor Rules for Urinary Table 2 (Urinary subtypes), Other Sites Table 16 (uterine corpus primaries) and Table 19 (vulvar primaries).

Are these the only sites in which one should code “poorly differentiated carcinoma (NOS)” as 8020 (undifferentiated carcinoma)?

How is histology coded if the only microscopic confirmation is from a metastatic site showing “poorly differentiated carcinoma” (NOS) or “invasive carcinoma, poorly differentiated” (NOS)?

Example 1: Primary pancreatic cancer diagnosed on imaging and confirmed with liver mets core biopsy showing “poorly differentiated carcinoma.” Immunostaining pattern was non-specific. No further workup or treatment was planned.

Other Sites - Table 11 (Pancreas Histologies) includes undifferentiated carcinoma (8020/3) as a valid histology; however, the synonyms/subtypes/variants do not mention poorly differentiated carcinoma. How should histology be coded for this case?

Example 2: Hemicolectomy with cecal tumor final diagnosis of “invasive carcinoma, poorly differentiated” and synoptic summary listing “Histologic type: Invasive carcinoma. Histologic grade: G3 of 4: poorly differentiated.”

Colorectal Table 1 (Specific Histologies and Subtypes/Variants) includes undifferentiated adenocarcinoma/carcinoma 8020 as a subtype of adenocarcinoma NOS. There is no mention of poorly differentiated in this context. How should histology be coded for this case?