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Produced: 10/28/2025 3:41 AM
Question 20220016
Inquiry Details
References:
WHO Class Endocrine Tumors, 96. 4th edition
Question:
Histology--Thyroid: What is the correct histology code for a follicular carcinoma, minimally invasive, oncocytic variant of the thyroid? See Discussion.
Discussion:
There is an ICD-O histology code for follicular carcinoma, minimally invasive (8335/3) as well as follicular carcinoma, oxyphilic cell (8290/3). Per SINQ 20150045, the term oncocytic is synonymous with oxyphilic in this context.
The Multiple Primaries/Histology General Instructions and histology rules do not include the term “variant” as a term that can be used to code a further histologic subtype. The term “variant” can be used for the Other Sites (non-updated STR sites) when the ICD-O-3.2 (or ICD-O-3 for older cases) provides the term “variant” in the histology name.
Answer:
Code follicular carcinoma, minimally invasive, oncocytic variant of the thyroid to follicular carcinoma, oncocytic variant (8290/3). The term "variant" is commonly used in thyroid histologies and if appropriate, used to determine histology code. The WHO Classification of Tumors of Endocrine Organs, 4th edition, lists synonyms for 8290/3 as Hürthle cell carcinoma; oncoycytic carcinoma; oxyphilic carcinoma; follicular carcinoma, Hürthle cell type; and follicular carcinoma, oncocytic variant.
