D47.09 ICD-10-CM Code: Other mast cell neoplasms of uncertain behavior
D47.09 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Neoplasms (C00-D49) / Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes (D37-D48)
D47.09
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther mast cell neoplasms of uncertain behavior
Other abnormal growths of mast cells that don't fit into the cutaneous or systemic categories.
Buddy Insight
Other mast cell neoplasms of uncertain behavior captures mast cell proliferative disorders that do not fit into the cutaneous or systemic mastocytosis categories.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
MappedHCC 21
Code-level coefficient reference
Code Book Path
Inclusion Terms
Official- Extracutaneous mastocytoma
- Mast cell tumor NOS
- Mastocytoma NOS
- Mastocytosis NOS
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for D47.09 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for D47.09 in this effective period.
Excludes 1
Official- congenital cutaneous mastocytosis (Q82.2)
- histiocytic neoplasms of uncertain behavior (D47.Z9)
- malignant mast cell neoplasm (C96.2-)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for D47.09 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for D47.09 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for D47.09 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 D47.09 an HCC code?
D47.09 is not in the CMS-HCC V28 or V24 community payment model. D47.09 has a separate mapping under the Part D RxHCC model (HCC 21 (Lymphomas and Other Hematologic Cancers)); the applicable result needs member context.
- Code
- D47.09
- Description
- Other mast cell neoplasms of uncertain behavior
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. 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 context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work D47.09 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT Criteria for D47.09
For D47.09 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 D47.09 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
D47.09 is the ICD-10-CM diagnosis code for other mast cell neoplasms of uncertain behavior. Other abnormal growths of mast cells that don't fit into the cutaneous or systemic categories. D47.09 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).
D47.09 has no mapping under the CMS-HCC V28 or V24 community payment models. D47.09 has a separate mapping under the Part D RxHCC model (HCC 21 (Lymphomas and Other Hematologic Cancers)); the applicable result needs member context. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.
Use this code for mast cell neoplasms that don't meet criteria for cutaneous (D47.01) or systemic (D47.02) mastocytosis.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for D47.09 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Other mast cell neoplasms of uncertain behavior captures mast cell proliferative disorders that do not fit into the cutaneous or systemic mastocytosis categories. This includes rare entities such as mast cell sarcoma and extracutaneous mastocytoma, which have unique clinical presentations and management approaches distinct from typical mastocytosis.
Documentation Requirements
- ✓Documentation should specify the type of mast cell neoplasm and explain why it does not meet criteria for cutaneous (D47.01) or systemic (D47.02) mastocytosis.
- ✓Tissue biopsy confirming mast cell proliferation is required.
- ✓Document the anatomical location, tryptase levels, KIT mutation status, and any associated symptoms.
Commonly Confused Codes
- •D47.01 (cutaneous mastocytosis) and D47.02 (systemic mastocytosis) are more specific and should be used when criteria are met.
- •C96.20 (malignant mast cell neoplasm) is used when malignant behavior is confirmed.
- •D47.9 (neoplasm of uncertain behavior of lymphoid/hematopoietic tissue, unspecified) is less specific and should not be used when a mast cell origin is established.