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SEER Inquiry System - Report
Produced: 05/28/2026 1:34 PM
Question 20240006
Inquiry Details
References:
#1: WHO Class Hem & Lymph Tumors. 4th edition
#2: Subject matter expert
Question:
Primary Site/Histology--Heme & Lymphoid Neoplasms: What are the correct primary site and histology for patient diagnosed with an oropharyngeal soft tissue mass revealing plasma cell neoplasm with 5-10% of marrow cellularity in 2022? See Discussion.
Discussion:
Patient underwent excision of an oropharyngeal soft tissue mass revealing plasma cell neoplasm with extensive amyloid deposition. During work-up, bone marrow biopsy also revealed involvement by plasma cell neoplasm, with 5-10% of marrow cellularity. No amyloid seen in bone marrow. Patient was referred for radiation of the oropharyngeal mass. Per medical oncology qualifying best for the diagnosis of solitary extramedullary plasmacytoma with minimal marrow involvement. Decision made for observation by medical oncology in view of “minimal” bone marrow involvement. Question: Is rule M11 correct, and I abstract this case as a plasma cell myeloma, 9732/3, C421?
Answer:
Updated May 2026
Code as an oropharyngeal primary site and histology as solitary plasmacytoma (9734/3) based on the pathologist's diagnosis of extramedullary plasmacytoma with minimal bone marrow involvement (and a diagnosis consistent with "plasma cell neoplasm" which is not multiple myeloma). Our expert hematopathologist was consulted on this case.
