An official website of the United States government
Home
SEER Inquiry System - Report
Produced: 09/24/2026 3:01 PM
Question 20200064
Inquiry Details
References:
#1: WHO Class Hem & Lymph Tumors. Revised 4th edition
#2: Heme & Lymph Manual & DB. September 2020; Effective with Cases Diagnosed 1/1/2010 and Forward
Question:
Primary site--Heme &Lymphoid Neoplasms: What is the primary site of two extraosseous plasmacytomas, with positive pathology of right orbit and left lung. The patient's bone marrow biopsy, flow, and peripheral blood smear were negative. Is this coded as 9732/3, multiple myeloma (Primary Site and Histology Rule PH2) with the primary site as C809 (PH27)? Or is the primary site C421 since code 9732 says primary site is always C421, though bone marrow came back as negative?
Discussion:
Answer:
Assign the primary site to C421 since that is the only allowable primary site for plasma cell myeloma, even though the bone marrow was negative. According to the revised criteria from the WHO Blue Book for Hematopoietic and Lymphoid Neoplasms (2017), the presence of multiple plasmacytomas is plasma cell myeloma (9732/3).
