An official website of the United States government
Home
SEER Inquiry System - Report
Produced: 04/19/2026 4:26 AM
Question 20031171
Inquiry Details
References:
#1: ICD-O-3, 79
#2: WHO Class Digest System Tumors, 95. 2000
Question:
Discussion:
In the ICD-O-3, pseudomyxoma peritonei has a behavior code of 6, indicating that it is malignant. Does this imply that pseudomyxoma peritonei is always a reportable malignancy? In the past, our pathologist consultant told us that pseudomyxoma peritonei is only a reportable malignancy if the underlying tumor is malignant. A benign cystadenoma of the appendix, for example, can rupture causing pseudomyxoma perionei. Does SEER agree with our pathologist consultant?
Example: Patient was found to have psuedomyxoma peritonei. Right hemicolectomy was done. Path reported an appendix with mucinous cystic tumor of undetermined malignant potential. A definite diagnosis of cancer can not be rendered.
Answer:
Reportability is determined from the behavior of the primary tumor and the behavior of implants. If either are malignant, the case is reportable.
The case example does not seem to be reportable, based on the available information. Cancer diagnosis has not been made according to the pathology report.
