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SEER Inquiry System - Report
Produced: 09/12/2025 5:32 AM
Question 20180004
Inquiry Details
References:
2007 MP/H Rules. Other sites
Question:
Reportability/MP/H Rules/Multiple primaries: Is a ganglioneuroblastoma (9490/3) following a melanoma (8720/3) a new primary if the diagnosing pathologist states: "Given the clinical context and patient age, then I believe that this may represent transdifferentiation of metastatic melanoma'? If this is a new primary, what MP/H rule would apply? See Discussion.
Discussion:
March 2017 lung biopsy showing metastatic melanoma. Subsequent workup shows imaging with additional metastatic involvement of multiple bone sites but no primary tumor is identified. Chemotherapy is started in May 2017.
July 2017 biopsy of right lower quadrant mass has a final diagnosis of ganglioneuroblastoma and pathologist's comment states I believe that this may represent transdifferentiation of metastatic melanoma. Later, partial colectomy of transverse colon Gross Description indicates this was centered in the mesentery.
Answer:
Abstract two primaries: 1. unknown primary site and 2. peripheral nerves and autonomic nervous system of abdomen, based on Multiple Primaries/Histology for Other Sites Rule M11 (topography codes that differ at the second or third character). While it is possible in rare cases that one tumor transforms into the other, transformations do not factor into the current MP/H rules.
