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SEER Inquiry System - Report
Produced: 02/05/2026 12:02 AM
Question 20010148
Inquiry Details
References:
#1: AJCC Cancer Staging Manual, 396. Sixth Edition
#2: SEER EOD-88,3rd Ed, 180
Question:
EOD-Extension--Lymphoma: Would a lymphoma involving mesenteric and retroperitoneal nodes (both site code C77.2) be coded to extension 10 [Involvement of a single lymph node region; Stage I], based on the fact that while more than one "chain" is involved only one "region" is involved?
Discussion:
Answer:
For cases diagnosed 1998-2003:
Code the EOD-Extension field to 20 [Involvement of two or more lymph node regions on the same side of diaphram]. The AJCC lists mesenteric as a core nodal region, but does not list retroperitoneal lymph nodes as a part of this region, so retroperitoneal is a separate region.
The EOD staging scheme for lymphoma uses lymph node REGIONS as the criteria for assigning the extension code. Use the AJCC Cancer Staging Manual as the definitive source for classifying lymph node regions, not the ICD-O-3. If it is a separate LN region per the AJCC, it is coded in the EOD as a separate region.
According to the AJCC curator, the nodal regions are defined in Kaplan's book on Hodgkin disease. Bilateral cervical, or axillary, or hilar, or pelvic, or inguinal nodes count as two regions. Mediastinal and para-aortic lymph nodes count as one region regardless of laterality as they are centrally located. A large mediastinal mass constitutes one region involved regardless of the size.
