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SEER Inquiry System - Report
Produced: 09/18/2025 3:57 PM
Question 20110143
Inquiry Details
References:
Heme & Lymph Manual & DB
Question:
Multiple primaries--Heme & Lymphoid Neoplasms: How many and what primary site(s) are to be accessioned when biopsies of clavicular and neck skin lesions are both consistent with mycosis fungoides? See Discussion.
Discussion:
Per the Heme DB and Manual, this is a single primary; however, per the MP/H Rules, this would be multiple primaries. Which rules apply to this case?
Answer:
For cases diagnosed 2010 and forward, access the Hematopoietic Database at http://seer.cancer.gov/seertools/hemelymph.
When there is a question of whether the SEER MP/H Rules or Hematopoietic and Lymphoid Neoplasm Rules apply, check the histology and refer to the Case Reportability Instructions in the Hematopoietic and Lymphoid Neoplasm Manual. All ICD-O-3 morphology codes in the range 9590 - 9992 are included in the Hematopoietic Rules. Mycosis Fungoides [9700/3] is included in this range. Therefore, the SEER MP/H Rules do not apply to mycosis fungoides.
This case should be accessioned as a single primary: mycosis fungoides [9700/3] of the skin, NOS [C449]. Per Rule M2 abstract a single primary when there is a single histology.
Note that in the Primary Site(s) section of the Heme DB, it states the primary site must always be coded to skin (C440 - C449) for mycosis fungoides. Because the primary site is stated in this section of the Heme DB, it is not necessary to use the Primary Site Rules to determine the primary site. Code the primary site to C449 [skin, NOS] because the patient has multiple sites of skin involvement and there is no documentation indicating which subsite of skin was the origin of the mycosis fungoides.
SEER*Educate provides training on how to use the Heme Manual and DB. If you are unsure how to arrive at the answer in this SINQ question, refer to SEER*Educate to practice coding hematopoietic and lymphoid neoplasms. Review the step-by-step instructions provided for each case scenario to learn how to use the application and manual to arrive at the answer provided. https://educate.fhcrc.org/LandingPage.aspx.
History:
This SINQ question has been updated to the Hematopoietic & Lymphoid Neoplasm Manual & Database published January 2014.
The original answer below was written based on the rules in 2010
When there is a question of whether the SEER MP/H Rules or Hematopoietic and Lymphoid Neoplasm Rules apply, use the histology and refer to the Case Reportability Instructions in the Hematopoietic and Lymphoid Neoplasm Manual. Case Reportability Rule 9 indicates all ICD-O-3 morphology codes in the range 9590 - 9992 are included in the Hematopoietic Rules. Mycosis Fungoides [9700/3] is included in this range and therefore the SEER MP/H Rules do not apply to mycosis fungoides.
For cases diagnosed 2010-2011, access the Hematopoietic Database at
http://seer.cancer.gov/tools/heme/.
Click on Hematopoietic Project. Click on Hematopoietic and Lymphoid Database. For 2010-2011 diagnoses, click on the "use the 2010 database" label in the upper right corner of the screen. The 2010 Hematopoietic Coding Manual (PDF) button will appear to indicate the correct version of the program is available now for query.
This case should be accessioned as a single primary: mycosis fungoides [9700/3] of the skin, NOS [C449]. The steps used to arrive at this decision are:
Enter in the Heme DB to find the histology. Click on the SEARCH button. Ensure that the term "mycosis fungoides" [9700/3] is highlighted on the screen.
Click on the 2010 HEMATOPOIETIC CODING MANUAL (PDF) button. Once in the manual, locate one of the three formats (i.e., flowchart, matrix or text) to check the Multiple Primary Rules. The rules are intended to be reviewed in consecutive order from Rule M1 to Rule M13. Stop at the first rule that applies to the case you are processing. Abstract as a single primary when there is a single histology. Although there are two primary sites (skin of clavicle and neck) there is only one histology present, mycosis fungoides [9700/3].
Note that in the PRIMARY SITE(S) section of the Heme DB it states the primary site must always be coded to skin (C440 - C449) for mycosis fungoides. Because the primary site is stated in this section of the Heme DB, it is not necessary to use the Primary Site Rules to determine the primary site. Code the primary site to C449 [skin, NOS] because the patient has multiple sites of skin involvement and there is no documentation indicating which subsite of skin was the origin of the mycosis fungoides.
