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Name
ICD-O-3 Morphology
9734/3: Extraosseous plasmacytoma
Effective
2001 and later
Reportable
for cases diagnosed
1978 and later
Primary Site(s)
See Module 7
Primary site cannot be bone (C400-419). Most common sites of involvement: upper respiratory tract (80%), oropharynx, nasopharynx, sinuses, larynx, gastrointestinal tract, lymph nodes, bladder, CNS, breast, thyroid, testis, parotid gland, and skin.
See Plasma Cell Myeloma, 9732/3 if there are multiple plasmacytomas or the bone marrow is involved.
See abstractor notes
See Plasma Cell Myeloma, 9732/3 if there are multiple plasmacytomas or the bone marrow is involved.
See abstractor notes
Coding Manual:
Hematopoietic Coding Manual (PDF)
Abstractor Notes
The presence of multiple plasmacytomas is diagnostic of plasma cell myeloma. Code as C421 (bone marrow), 9732/3.
Note: Code primary site as C421 even if the bone marrow is negative or the bone marrow was not assessed.
Extramedullary plasmacytoma (EMP) is part of the Plasma cell neoplasms and other diseases with paraproteins lineage table in the WHO 5th edition of Hematolymphoid Tumors. (See Appendix B in the Hematopoietic Manual, Table B17)
Do not code primary site to C40. _ or C41._. These category codes should only be used with histology 9731/3.
The presence of a plasmacytoma and a diagnosis of plasma cell myeloma diagnosed during the initial clinical workup is evidence of advanced disease. One primary is abstracted, the plasma cell myeloma (See Rule M11)
The presence of a plasmacytoma after a diagnosis of plasma cell myeloma is evidence of advanced disease and not a new primary (See Rule M13)
The phrase "plasma cell neoplasm" is an umbrella term used for many diseases, some of which are not reportable. If the only diagnosis is "plasma cell neoplasm," then do not report the case. If it is "plasma cell neoplasm" consistent with a plasmacytoma or multiple myeloma, then the case would be reportable.
If the diagnosis is "plasmacytoma" and there is no additional information to indicate if it's a plasmacytoma of the bone or an extramedullary plasmacytoma, default to plasmacytoma of the bone and assign histology, 9731/3 and primary site C419.
Extramedullary plasmacytomas most commonly arises in the upper respiratory tract (nasal cavity, paranasal sinuses, nasopharynx, larynx). Extramedullary plasmacytomas rarely involve the lymph nodes, lungs, gastrointestinal tract, genitourinary tract and skin.
There is no evidence of bone marrow plasmacytosis other than the solitary lesion. Vertebral lesions may be associated with symptomatic cord compression.
An M-protein is found in the serum or urine in 24-72% of patients.
Note: Code primary site as C421 even if the bone marrow is negative or the bone marrow was not assessed.
Extramedullary plasmacytoma (EMP) is part of the Plasma cell neoplasms and other diseases with paraproteins lineage table in the WHO 5th edition of Hematolymphoid Tumors. (See Appendix B in the Hematopoietic Manual, Table B17)
Do not code primary site to C40. _ or C41._. These category codes should only be used with histology 9731/3.
The presence of a plasmacytoma and a diagnosis of plasma cell myeloma diagnosed during the initial clinical workup is evidence of advanced disease. One primary is abstracted, the plasma cell myeloma (See Rule M11)
The presence of a plasmacytoma after a diagnosis of plasma cell myeloma is evidence of advanced disease and not a new primary (See Rule M13)
The phrase "plasma cell neoplasm" is an umbrella term used for many diseases, some of which are not reportable. If the only diagnosis is "plasma cell neoplasm," then do not report the case. If it is "plasma cell neoplasm" consistent with a plasmacytoma or multiple myeloma, then the case would be reportable.
If the diagnosis is "plasmacytoma" and there is no additional information to indicate if it's a plasmacytoma of the bone or an extramedullary plasmacytoma, default to plasmacytoma of the bone and assign histology, 9731/3 and primary site C419.
Extramedullary plasmacytomas most commonly arises in the upper respiratory tract (nasal cavity, paranasal sinuses, nasopharynx, larynx). Extramedullary plasmacytomas rarely involve the lymph nodes, lungs, gastrointestinal tract, genitourinary tract and skin.
There is no evidence of bone marrow plasmacytosis other than the solitary lesion. Vertebral lesions may be associated with symptomatic cord compression.
An M-protein is found in the serum or urine in 24-72% of patients.
Diagnostic Confirmation
This histology can be determined by positive histology (including peripheral blood) with or without genetics and/or immunophenotyping. Review the Definitive Diagnostic Methods, Immunophenotyping and Genetics Data sections below, and the instructions in the Hematopoietic Manual for further guidance on assigning Diagnostic confirmation.
Module Rule
Module 2: PH2
Alternate Names
Extraosseous plasmacytoma
Plasmacytoma, NOS (occurring outside of bone)
Solitary plasmacytoma (occurring outside of bone)
Plasmacytoma, extramedullary
Definition
Plasmacytoma is a solitary neoplasm of clonal plasma cells without evidence of plasma cell (multiple) myeloma or end-organ damage due to plasma cell neoplasia. (WHO 5th edition)
Definitive Diagnostic Methods
Cytogenetics
Genetic testing
Histologic confirmation
Immunohistochemistry
Immunophenotyping
Genetics Data
MYC aberrations
t(11;14)(q13;q32) (IGH.CCNDI) lacking
Immunophenotyping
C19+ (expression/positive)
CD20+ (expression/positive)
CD45+ (expression/positive)
CD56+ (expression/positive)
Cyclin DI (usually lacking)
Treatments
Chemotherapy
Radiation therapy
Surgery
Transformations to
Transformations from
None
Same Primaries
Corresponding ICD-10 Codes (Cause of Death codes only)
C90.2 Plasmacytoma, extramedullary
Corresponding ICD-10-CM Codes (U.S. only)
C90.2 Extramedullary plasmacytoma (effective October 01, 2015)
Signs and Symptoms
Diagnostic Exams
Blood and urine immunoglobulin studies
Blood chemistry studies
Bone marrow aspiration and biopsy
Cytogenetic analysis
Serum and urine protein electrophoresis and immunofixation
Skeletal survey
Tissue biopsy
Twenty-four-hour urine test
Progression and Transformation
Regional recurrences occur in ~25% of patients
Occasionally metastasis to distant extraosseous sites
Transformation to plasma cell myeloma occurs in ~15% of cases
Epidemiology and Mortality
Age: 55 years median age
Incidence: 3-5% of plasma cell neoplasms
Sex: male predominance
Survival: ~70% of patients remain disease free at 10 years
Sources
WHO Classification of Tumours Editorial Board. Haematolymphoid tumours. Lyon (France): International Agency for Research on Cancer; 2024. (WHO classification of tumours series, 5th ed.; vol. 11). https://publications.iarc.who.int/637.
Section: Plasma cell neoplasms and other diseases with paraproteins
Pages: Part B: 622-624
Section: Plasma cell neoplasms and other diseases with paraproteins
Pages: Part B: 622-624
International Classification of Diseases for Oncology, 3rd edition (including revisions). Geneva: World Health Organization, 2001, 2011, 2020.
Section: ICD-O-3.2 (2020) Morphological Codes
Pages: http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577
Section: ICD-O-3.2 (2020) Morphological Codes
Pages: http://www.iacr.com.fr/index.php?option=com_content&view=category&layout=blog&id=100&Itemid=577
PDQ® Adult Treatment Editorial Board. PDQ Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment. Bethesda, MD: National Cancer Institute. Updated <03/28/2025>. Available at: https://www.cancer.gov/types/myeloma/hp/myeloma-treatment-pdq. Accessed <03/30/2025>. [PMID: 26389362]
Section: Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment (PDQ®)–Health Professional Version
Pages: https://www.cancer.gov/types/myeloma/hp/myeloma-treatment-pdq
Section: Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment (PDQ®)–Health Professional Version
Pages: https://www.cancer.gov/types/myeloma/hp/myeloma-treatment-pdq
