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SEER Inquiry System - Report
Produced: 05/24/2026 3:03 PM
Question 20051006
Inquiry Details
References:
ICD-O-3
Question:
Multiple Primaries (Pre-2007)/Histology (Pre-2007)--Thyroid: How is histology coded for the tumor(s) that exist when the thyroidectomy addendum diagnosis is "Morphologic and IHC evaluations reveal two tumors: papillary thyroid carcinoma and squamous cell carcinoma." See Discussion.
Discussion:
The original final diagnosis after a thyroidectomy is "papillary carcinoma of the thyroid with an adjacent invasive squamous cell carcinoma, moderately differentiated." Per the additional addendum comment: "The findings can be interpreted in one of 2 different ways. Either there is a collision tumor of papillary thyroid and squamous cell carcinoma (with the squamous cell ca originating at a site other than the thyroid gland.) Or, less likely, there is a malignant squamous differentiation in the papillary thyroid carcinoma." A university hospital consultation report states the diagnosis as: "Spindle cell squamous cell carcinoma arising in association and from papillary carcinoma, predominantly tall cell variant..." Is this 2 thyroid primaries: 8344/3 [papillary carcinoma, tall cell] and 8074/3 [squamous cell carcinoma, spindle cell]?
Answer:
For tumors diagnosed prior to 2007:
Our pathologist consultant agrees with the consultant's diagnosis. Therefore, abstract this as one primary of the thyroid. Code the histology as 8344 [Papillary tall cell]. This is the most appropriate histology code available for this complex case.
For tumors diagnosed 2007 or later, refer to the MP/H rules. If there are still questions about how this type of tumor should be coded, submit a new question to SINQ and include the difficulties you are encountering in applying the MP/H rules.
Cancer Site Category:
Thyroid
Data Item Category:
Histology
Other Category:
Multiple primaries
Year:
2005
