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Question: 20120065 Status

Source 1:   2007 MP/H Rules
Source 2:   2012 SEER Manual

MP/H Rules/Primary site: What is the primary site and histology for a focus of papillary thyroid cancinoma, follicular variant, arising in thyroid tissue of mature cystic teratoma of the ovary?


For cases diagnosed 2007 or later, code the primary site to ovary [C56.9] and the histology to papillary carcinoma, follicular variant [8340/3].

The steps used to arrive at this decision are:

Step 1: Refer to the 2012 SEER Manual for help to determine the primary site. This neoplasm is arising in a teratoma of the ovary. Per the 2012 SEER Manual, in this case the site is coded to ovary [56.9] because that is where the tumor originated. Although the teratoma contains thyroid tissue, it arose in the ovary. Teratomas are unusual in that they contain all three germ cell layers from which an embryo forms. It is not unusual to have malignancies that are usually primary to the thyroid, liver, brain, lung, etc., originate in a teratoma.

Step 2: Open the Multiple Primary and Histology Coding Rules Manual. Choose one of the three formats (i.e., flowchart, matrix or text). Go to the Other Sites Histology rules because site specific rules have not been developed for this primary.

Step 3: Start with the SINGLE TUMOR: INVASIVE ONLY module, rule H8. The rules are intended to be reviewed in consecutive order within a module. Stop at Rule H15. Code the histology as papillary carcinoma, follicular variant [8340/3].


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