D49.6 ICD-10-CM Code: Neoplasm of unspecified behavior of brain
D49.6 maps to CMS-HCC V28 23. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Neoplasms (C00-D49) / Neoplasms of unspecified behavior (D49)
D49.6
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceNeoplasm of unspecified behavior of brain
A tumor or growth in the brain whose behavior (whether it will grow, spread, or cause harm) cannot be determined from the available information.
Buddy Insight
This code identifies brain neoplasms where the biological behavior cannot be determined from available pathologic or clinical data.
CMS-HCC V28
MappedHCC 23
Coefficient HCC 23: 0.186 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 012
Code-level coefficient reference
ESRD/PACE
MappedHCC 12
Code-level coefficient reference
RXHCC
MappedHCC 22
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for D49.6. Check the code and parent instructions in the Code Book.
Excludes 2
Official- neoplasms of uncertain behavior (D37-D44, D48)Inherited from D49
Related Codes
Includes
Official- 'growth' NOSInherited from D49
- neoplasm NOSInherited from D49
- new growth NOSInherited from D49
- tumor NOSInherited from D49
Excludes 1
Official- neoplasm of unspecified behavior of cerebral meninges (D49.7)
- neoplasm of unspecified behavior of cranial nerves (D49.7)
Code First
OfficialNo Code First sequencing instructions are included in this display for D49.6. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for D49.6. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for D49.6. Check the code and parent instructions in the Code Book.
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 D49.6 an HCC code?
Yes. D49.6 (Neoplasm of unspecified behavior of brain) maps to HCC 23, Prostate, Breast, and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.186. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: D49.6 is billable and maps to V28 HCC 23, Prostate, Breast, and Other Cancers and Tumors. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- D49.6
- Description
- Neoplasm of unspecified behavior of brain
- HCC (V28)
- HCC 23 — Prostate, Breast, and Other Cancers and Tumors
- RAF reference coefficient
- 0.186
- 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 D49.6 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for D49.6
For D49.6, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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What This Code Means
D49.6 is the ICD-10-CM diagnosis code for neoplasm of unspecified behavior of brain. A tumor or growth in the brain whose behavior (whether it will grow, spread, or cause harm) cannot be determined from the available information. D49.6 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering neoplasms of unspecified behavior (d49).
Under the CMS-HCC V28 risk adjustment model, D49.6 maps to Prostate, Breast, and Other Cancers and Tumors (HCC 23) with a source-labeled community, non-dual, aged reference coefficient of 0.186. No V24 mapping is shown for D49.6; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Use this code only when the pathology report explicitly states 'unspecified behavior' or when behavior cannot be determined. For D49.6, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, and MEAT documentation criteria for D49.6 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the pathology report explicitly states 'unspecified behavior' or when behavior cannot be determined
- •If behavior is later determined to be benign or malignant, update the code to the appropriate D3x or C7x code
Clinical Significance
This code identifies brain neoplasms where the biological behavior cannot be determined from available pathologic or clinical data. These tumors may be awaiting definitive biopsy results or may have ambiguous histologic features that prevent classification as benign, malignant, or uncertain behavior. The clinical impact is significant because brain tumors of any behavior carry neurological risk and require monitoring or intervention.
Documentation Requirements
- ✓Documentation must include the anatomic location within the brain, imaging findings (Magnetic Resonance Imaging or Computed Tomography), reason why behavior cannot be determined (e.g., awaiting biopsy, inconclusive pathology), and current management plan.
- ✓If a biopsy or surgical specimen later clarifies behavior, the code should be updated to the appropriate benign (D33.x), uncertain (D43.x), or malignant (C71.x) category.
Excludes 1, Do NOT code together
Commonly Confused Codes
- •D49.6 vs. D43.0-D43.2 (Neoplasm of uncertain behavior of brain) -
- •use D43 codes when pathology confirms uncertain behavior specifically. D49.6 vs. C71.x (Malignant neoplasm of brain) -
- •use C71 when malignancy is confirmed. D49.6 vs. D33.x (Benign neoplasm of brain) -
- •use D33 when benign behavior is confirmed on pathology.