What is ICD-10 code D46.9?

D46.9 is the ICD-10-CM diagnosis code for Myelodysplastic syndrome, unspecified. A bone marrow disorder where blood cells cannot be produced normally, but the specific type or subtype cannot be determined. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). D46.9 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D46.9 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. D46.9 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. D46.9 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 D46.9?

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 D46.9, V28 maps to Lymphoma and Other Cancers at RAF 0.105 while V24 mapped to Severe Hematological Disorders at RAF 0.666. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting D46.9?

This is a catch-all code for myelodysplastic syndromes when subtype is not specified Always attempt to identify the specific MDS subtype (D46.0-D46.A) for more accurate coding Because D46.9 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.

D46.9 ICD-10 Code: Myelodysplastic syndrome

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupD46.9Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes (D37-D48)

D46.9

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

Myelodysplastic syndrome, unspecified

A bone marrow disorder where blood cells cannot be produced normally, but the specific type or subtype cannot be determined.

Buddy Insight

Myelodysplastic syndrome, unspecified, is a bone marrow failure disorder characterized by ineffective hematopoiesis, peripheral cytopenias, and risk of transformation to acute myeloid leukemia.

CMS-HCC V28

Mapped

HCC 19

Lymphoma and Other Cancers

RAF 0.105

CMS-HCC V24

Mapped

HCC 46

Severe Hematological Disorders

RAF 0.666

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 46

Severe Hematological Disorders

RAF 0.0

RXHCC

Mapped

HCC 19

Lymphoma and Other Cancers

RAF 0.0

Code Trumping

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Code Book Path

Official

D46Myelodysplastic syndromes

D46.9Myelodysplastic syndrome, unspecified

Inclusion Terms

Official

Myelodysplasia NOS

Excludes 2

Official

drug-induced aplastic anemia (D61.1)

Related Child Codes

Official

D46.0Refractory anemia without ring sideroblasts, so stated

D46.1Refractory anemia with ring sideroblasts

D46.2Refractory anemia with excess of blasts [RAEB]

D46.4Refractory anemia, unspecified

D46.ARefractory cytopenia with multilineage dysplasia

Includes

Official

ICD-10-CM does not list Includes notes for D46.9 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for D46.9 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for D46.9 in this effective period.

Use Additional

Official

code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Code Also

Official

ICD-10-CM does not list Code Also instructions for D46.9 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Use this code when myelodysplastic syndrome is diagnosed but the specific subtype is not documented.

A provider query should be initiated for bone marrow biopsy results, cytogenetic analysis, and blast percentage to enable more specific coding.

Document peripheral blood counts, transfusion dependence, and any infections or bleeding complications.

MEAT Support

HCC Buddy guidance

Use this code when myelodysplastic syndrome is diagnosed but the specific subtype is not documented.

A provider query should be initiated for bone marrow biopsy results, cytogenetic analysis, and blast percentage to enable more specific coding.

Document peripheral blood counts, transfusion dependence, and any infections or bleeding complications.

Audit Caution

HCC Buddy guidance

Always attempt to identify the specific myelodysplastic syndrome subtype from bone marrow pathology before using this unspecified code.

This code may trigger audit queries from payers seeking more specific documentation.

Do not use this code for cytopenias of unclear etiology without confirmed myelodysplastic features on bone marrow examination.

Common Mistakes

HCC Buddy guidance

D46.0 through D46.C are specific myelodysplastic syndrome subtypes and should be used when documentation permits.

D75.89 (other specified diseases of blood) may be used for other hematologic conditions.

C92.00 (acute myeloblastic leukemia) is used when myelodysplastic syndrome has transformed with 20% or more blasts.

D47.1 (chronic myeloproliferative disease) is a related but distinct entity.

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is D46.9 an HCC code?

Yes. D46.9 maps to Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model (and Severe Hematological Disorders under V24).

HCC Category Mapping

V28HCC 19, Lymphoma and Other Cancers

0.105

V24HCC 46, Severe Hematological Disorders

0.666

ESRDHCC 46, Severe Hematological Disorders

0.000

RxHCCHCC 19, Lymphoma and Other Cancers

0.000

RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.

MEAT Criteria for D46.9

For D46.9to 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 D46.9 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

D46.9 is the ICD-10-CM diagnosis code for myelodysplastic syndrome, unspecified. A bone marrow disorder where blood cells cannot be produced normally, but the specific type or subtype cannot be determined. D46.9 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes (d37-d48).

Under the CMS-HCC V28 risk adjustment model, D46.9 maps to Lymphoma and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 0.105. Under the older CMS-HCC V24 model, D46.9 maps to Severe Hematological Disorders (HCC 46) with a community, non-dual, aged base RAF weight of 0.666. 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.

This is a catch-all code for myelodysplastic syndromes when subtype is not specified. Because D46.9 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 D46.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a catch-all code for myelodysplastic syndromes when subtype is not specified
•Always attempt to identify the specific MDS subtype (D46.0-D46.A) for more accurate coding

Clinical Significance

Myelodysplastic syndrome, unspecified, is a bone marrow failure disorder characterized by ineffective hematopoiesis, peripheral cytopenias, and risk of transformation to acute myeloid leukemia. This unspecified code indicates that the specific World Health Organization subtype has not been established, which limits prognostic stratification and treatment planning.

Documentation Requirements

✓Use this code when myelodysplastic syndrome is diagnosed but the specific subtype is not documented.
✓A provider query should be initiated for bone marrow biopsy results, cytogenetic analysis, and blast percentage to enable more specific coding.
✓Document peripheral blood counts, transfusion dependence, and any infections or bleeding complications.

Commonly Confused Codes

•D46.0 through D46.C are specific myelodysplastic syndrome subtypes and should be used when documentation permits.
•D75.89 (other specified diseases of blood) may be used for other hematologic conditions.
•C92.00 (acute myeloblastic leukemia) is used when myelodysplastic syndrome has transformed with 20% or more blasts.
•D47.1 (chronic myeloproliferative disease) is a related but distinct entity.