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SEER Inquiry System - Report
Produced: 11/14/2025 1:21 AM
Question 20110057
Inquiry Details
References:
2010 SEER Manual. Appendix C
Question:
MP/H Rules/Behavior--Appendix: How do you code mucinous cancers of the appendix? Is a "low grade mucinous appendix tumor/neoplasm" with peritoneal spread reportable? See Discussion.
Discussion:
Low grade mucinous neoplasms can spread to the peritoneal cavity and in that sense are metastatic but histologically have bland/benign features (may be a benign cystadenoma that ruptured and spread by rupturing) are not a carcinoma. Thus, some have termed this group as DPAM (diseminated peritoneal adenomucinous) and not a true carcinoma. Others indicate that if you have metastasis the tumor is a carcinoma.
Answer:
For cases diagnosed 2007 or later, low-grade mucinous tumors of the appendix are a /1, borderline/uncertain behavior, and not reportable. These tumors do spread to the peritoneal cavity (pseudomyxoma peritonei). This spread, or deposits, or implants are also borderline/uncertain behavior and do not make the appendiceal tumor reportable. By contrast, a high-grade mucinous tumor of the appendix may produce malignant/invasive pseudomyxoma peritonei. When the pseudomyxoma peritonei are diagnosed as invasive or malignant, the mucinous tumor in the appendix is reportable as a /3.
