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SEER Inquiry System - Report
Produced: 02/09/2026 5:50 AM
Question 20230007
Inquiry Details
References:
#1: 2022 SEER Manual, 6. Reportability
#2: Subject matter expert
Question:
SEER Manual/Reportability--Appendix: Is low-grade appendiceal mucinous neoplasm (LAMN) with peritoneal spread followed by evidence of extraperitoneal metastatic disease reportable prior to 2022? See Discussion.
Discussion:
In 2021, the patient was diagnosed with a non-reportable appendiceal LAMN. Resection showed a tumor diffusely involving the appendix and perforating the visceral peritoneum, as well as extensive intraperitoneal metastasis. In 2023, a lung wedge resection revealed metastatic mucinous neoplasm involving lung parenchyma and pleura, consistent with metastasis of the known appendiceal primary. It is understood that intraperitoneal spread of an appendiceal LAMN does not make it reportable because the peritoneal disease is also non-invasive. Does extraperitoneal metastasis of an appendiceal LAMN diagnosed prior to 2022 make it invasive disease and therefore reportable?
Answer:
LAMN diagnosed prior to 1/1/2022 is not reportable even when it spreads or metastasizes according to our expert pathologist consultant. Spread of this neoplasm does not indicate malignancy. For this case to be reportable, the diagnosis must indicate “carcinoma” or “adenocarcinoma.” Pre-2022, LAMN is not reportable even when treated with surgery and chemotherapy. LAMN is reportable starting with cases diagnosed in 2022.
