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SEER Inquiry System - Report
Produced: 09/18/2025 1:52 AM
Question 20110028
Inquiry Details
References:
#1: 2007 MP/H Rules, 14
#2: WHO Class Endocrine Tumors, 67. 2004
Question:
Discussion:
Right lobectomy pathology report final diagnosis states: 1.9 cm Hurthle cell carcinoma (see comment). Comment: histologic diagnosis Hurthle cell carcinoma, probable follicular variant of papillary carcinoma with Hurthle cell features. Subsequent left lobectomy one week later showed a 2 mm microscopic focus of follicular variant of papillary carcinoma, encapsulated.
None of the rules seems to fit this scenario. The number of primaries reported for this case depends on the histology coded for each tumor. Does Rule M6 (Follicular and papillary tumors in the thyroid within 60 days of diagnosis are a single primary.) or M17 (Tumors with ICD-O-3 histology codes that are at the first (xxx), second (xxx) or third (xxx) number are multiple primaries.) apply? Does the case represent a single primary because both are papillary/follicular tumors or two primaries because one is Hurthle cell carcinoma, and one is papillary/follicular carcinoma (different histology at second digit)?
To code the histology for the larger tumor in the right lobe, which rule do we apply? Rule H11 (single histology of Hurthle cell carcinoma [8290] per path final diagnosis), H15 (tumor has both follicular and papillary carcinoma [8340], per path comment), or H17 (numerically higher code for 8340 because there is both Hurthle cell and papillary/follicular carcinoma)?
Answer:
Use the Multiple Primary and Histology Coding Rules Manual for cases diagnosed 2007 or later to determine the number of primaries. This is a single primary.
The Hurthle cell carcinoma is a synonym for follicular carcinoma according to the WHO. See page 67 of the 2004 WHO Classification of Tumours of Endocrine Organs. The steps used to arrive at this decision are:
Open the Multiple Primary and Histology Coding Rules manual. For a thyroid primary, use the Other Sites MP rules under one of the three formats (i.e., flowchart, matrix or text) to determine the number of primaries because the thyroid does not have site specific rules.
Start with the MULTIPLE TUMORS module, Rule M3. The rules are intended to be reviewed in consecutive order within the module from Rule M3 to Rule M18. You stop at the first rule that applies to the case you are processing.
. Follicular and papillary tumors in the thyroid within 60 days of diagnosis are a single primary. The patient has a tumor in each lobe of the thyroid with the same histology. Abstract a single primary for this patient.
Determine the histology code. For a thyroid, use one of the three formats (i.e., flowchart, matrix or text) under the Other Sites Histo rules to determine histology because thyroid primaries do not have site specific rules.
Start with the SINGLE TUMOR: INVASIVE ONLY module, Rule H8. The rules are intended to be reviewed in consecutive order within the module from Rule H8 to Rule H18. You stop at the first rule that applies to the case you are processing.
. Code follicular and papillary carcinoma of the thyroid to papillary carcinoma, follicular variant (8340). Use the comment to code the histology for the right lobectomy. "Probable" is an acceptable ambiguous term to use for coding histology. (See the Ambiguous Terms Used to Code Histology section of the General Instructions in the MP/H manual.)
