What is ICD-10 code C90.20?

C90.20 is the ICD-10-CM diagnosis code for Extramedullary plasmacytoma not having achieved remission. Extramedullary plasmacytoma, a tumor of plasma cells that occurs outside the bone marrow, that has not responded to treatment. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C90.20 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C90.20 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C90.20 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C90.20 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for C90.20?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C90.20, V28 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers at RAF 1.798 while V24 mapped to Lung and Other Severe Cancers at RAF 1.024. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting C90.20?

Extramedullary plasmacytoma occurs in soft tissues outside bone marrow; verify location is documented Fifth character '0' indicates no remission; document the site of the tumor for complete coding Because C90.20 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM C90.20: Extramedullary plasmacytoma

ICD-10-CM Code View

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Code lookupC90.20Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)

C90.20

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Extramedullary plasmacytoma not having achieved remission

Extramedullary plasmacytoma, a tumor of plasma cells that occurs outside the bone marrow, that has not responded to treatment.

Buddy Insight

CMS-HCC V28

Mapped

HCC 19

Myelodysplastic Syndromes, Mu...

RAF 1.798

CMS-HCC V24

Mapped

HCC 9

Lung and Other Severe Cancers

RAF 1.024

ACA/HHS

Mapped

HCC 9

HHS-HCC 9

Varies by metal level

ESRD/PACE

Mapped

HCC 9

Lung and Other Severe Cancers

RAF 0.181

RXHCC

Mapped

HCC 16

Multiple Myeloma and Plasma C...

RAF 14.205

Code Book Path

Official

C90Multiple myeloma and malignant plasma cell neoplasms

C90.2Extramedullary plasmacytoma

C90.20Extramedullary plasmacytoma not having achieved remission

Inclusion Terms

Official

Extramedullary plasmacytoma with failed remission
Extramedullary plasmacytoma NOS

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C90.20 in this effective period.

Related Child Codes

Official

C90.21Extramedullary plasmacytoma in remission

C90.22Extramedullary plasmacytoma in relapse

Includes

Official

ICD-10-CM does not list Includes notes for C90.20 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C90.20 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C90.20 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C90.20 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C90.20 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must include tissue biopsy confirming a monoclonal plasma cell tumor outside the bone marrow.

The specific extramedullary site must be documented.

Imaging confirming absence of additional lesions, bone marrow biopsy excluding myeloma, serum and urine protein studies, treatment approach (typically radiation), and non-remission status are required.

MEAT Support

HCC Buddy guidance

Documentation must include tissue biopsy confirming a monoclonal plasma cell tumor outside the bone marrow.

The specific extramedullary site must be documented.

Audit Caution

HCC Buddy guidance

Ensure the plasmacytoma is confirmed as extramedullary (outside bone) rather than a solitary bone plasmacytoma, which has a different code.

Rule out underlying multiple myeloma with appropriate workup before assigning this more localized diagnosis.

Document that bone marrow biopsy and skeletal survey are negative for systemic disease.

Common Mistakes

HCC Buddy guidance

C90.21 (extramedullary plasmacytoma in remission) requires documented remission.

C90.30 (solitary plasmacytoma) refers to bone plasmacytoma, which is within the skeletal system.

C90.00 (multiple myeloma) involves systemic disease with bone marrow infiltration.

D47.Z9 (neoplasm of uncertain behavior of lymphoid tissue) is for borderline lesions.

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C90.20 an HCC code?

Yes. C90.20 (Extramedullary plasmacytoma not having achieved remission) maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24), with a community non-dual aged RAF of 1.798. It is billable for payment year 2026.

Coder answer: C90.20 is billable and maps to V28 HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C90.20
Description: Extramedullary plasmacytoma not having achieved remission
HCC (V28): HCC 19 — Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers
RAF: 1.798
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 19, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers

1.798

V24HCC 9, Lung and Other Severe Cancers

1.024

ESRDHCC 9, Lung and Other Severe Cancers

0.181

RxHCCHCC 16, Multiple Myeloma and Plasma Cell Neoplasms

14.205

Each model's RAF is its CMS base weight for that model's standard population, so weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work C90.20 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C90.20

For C90.20 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C90.20 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C90.20 is the ICD-10-CM diagnosis code for extramedullary plasmacytoma not having achieved remission. Extramedullary plasmacytoma, a tumor of plasma cells that occurs outside the bone marrow, that has not responded to treatment. C90.20 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of lymphoid, hematopoietic and related tissue (c81-c96).

Under the CMS-HCC V28 risk adjustment model, C90.20 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 1.798. Under the older CMS-HCC V24 model, C90.20 maps to Lung and Other Severe Cancers (HCC 9) with a community, non-dual, aged base RAF weight of 1.024. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Extramedullary plasmacytoma occurs in soft tissues outside bone marrow; verify location is documented. Because C90.20 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for C90.20 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Extramedullary plasmacytoma occurs in soft tissues outside bone marrow; verify location is documented
•Fifth character '0' indicates no remission; document the site of the tumor for complete coding

Clinical Significance

Extramedullary plasmacytoma is a solitary tumor of neoplastic plasma cells occurring outside the bone marrow, most commonly in the upper respiratory tract including the nasopharynx, paranasal sinuses, and oropharynx. Unlike multiple myeloma, it is typically a localized disease amenable to radiation therapy. Non-remission status indicates the tumor persists or has progressed despite treatment.

Documentation Requirements

✓Documentation must include tissue biopsy confirming a monoclonal plasma cell tumor outside the bone marrow.
✓The specific extramedullary site must be documented.
✓Imaging confirming absence of additional lesions, bone marrow biopsy excluding myeloma, serum and urine protein studies, treatment approach (typically radiation), and non-remission status are required.

Commonly Confused Codes

•C90.21 (extramedullary plasmacytoma in remission) requires documented remission.
•C90.30 (solitary plasmacytoma) refers to bone plasmacytoma, which is within the skeletal system.
•C90.00 (multiple myeloma) involves systemic disease with bone marrow infiltration.
•D47.Z9 (neoplasm of uncertain behavior of lymphoid tissue) is for borderline lesions.