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SEER Inquiry System - Report
Produced: 05/11/2026 12:44 PM
Question 20021090
Inquiry Details
References:
2004 SEER Manual, 73
Question:
Primary Site--Ovary/Peritoneum: How should the Primary Site field be coded when no resection is done and it is uncertain whether the primary site is in the ovary or the peritoneum? See discussion.
Discussion:
CT: ascites, omental cake and peritoneal studding. H&P impression: probable ovarian or peritoneal primary. Repeat CT: no enlarged adnexal mass seen to suggest ca of ovary, but possibility couldn't be ruled out. Omental bx: Metastatic ca. Comment: "IHC stains have been performed and are not typical of ovarian ca, although do not exclude an ovarian primary." After the bx, there were two clinical diagnoses written a month apart with no evidence of further work-up between those dates. The first diagnosis was "ovarian ca". The second was "Peritoneal carcinomatosis 2 month ago; Primary is unknown, possibly ovarian."
Answer:
Use the best information available to identify the primary site. In this case, it is the physician's clinical assessment. Code the Primary Site to C56.9 [Ovary] for this example because the ovary is indicated to be the primary site according to the physicians involved.
When there is no surgical procedure involving the removal of the ovaries, code the Primary Site based on the clinical assessment of the disease location. If the disease is only noted to be in the peritoneum, code site to peritoneum, NOS. If the disease is seen clinically in both the ovary and the peritoneum, code site to ovary.
Cancer Site Category:
Ovary
Data Item Category:
Primary site
Other Category:
N/A
Year:
2002
