D46.9
BillableMyelodysplastic syndrome, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
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
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 D46.9 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 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
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.