D43.8 ICD-10-CM Code: Neoplasm of uncertain behavior of other specified parts of central nervous system
D43.8 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 Buddy coding tools
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FY 2026 Apr update / Neoplasms (C00-D49) / Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes (D37-D48)
D43.8
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceNeoplasm of uncertain behavior of other specified parts of central nervous system
This code describes a tumor or abnormal growth in the brain or spinal cord that doctors cannot yet definitively classify as either benign (non-cancerous) or malignant (cancerous). These uncertain tumors require further testing or monitoring to determine their true nature.
Buddy Insight
This code captures neoplasms of uncertain behavior in specified central nervous system locations not covered by other D43 codes, such as the cauda equina, optic nerve, or olfactory bulb.
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 D43.8. Check the code and parent instructions in the Code Book.
Excludes 2
OfficialNo Excludes 2 notes are included in this display for D43.8. Check the code and parent instructions in the Code Book.
Related Codes
Includes
OfficialNo Includes notes are included in this display for D43.8. Check the code and parent instructions in the Code Book.
Excludes 1
Official- neoplasms of unspecified behavior (D49.-)Inherited from D37-D48, D43
- neoplasm of uncertain behavior of peripheral nerves and autonomic nervous system (D48.2)Inherited from D37-D48, D43
Code First
OfficialNo Code First sequencing instructions are included in this display for D43.8. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for D43.8. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for D43.8. 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 D43.8 an HCC code?
Yes. D43.8 (Neoplasm of uncertain behavior of other specified parts of central nervous system) 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: D43.8 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
- D43.8
- Description
- Neoplasm of uncertain behavior of other specified parts of central nervous system
- 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 D43.8 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for D43.8
For D43.8, 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
D43.8 is the ICD-10-CM diagnosis code for neoplasm of uncertain behavior of other specified parts of central nervous system. This code describes a tumor or abnormal growth in the brain or spinal cord that doctors cannot yet definitively classify as either benign (non-cancerous) or malignant (cancerous). These uncertain tumors require further testing or monitoring to determine their true nature. D43.8 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, D43.8 maps to Prostate, Breast, and Other Cancers and Tumors (HCC 23) with a source-labeled community, non-dual, aged reference coefficient of 0.186. 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 pathology or imaging findings show a lesion that cannot be definitively classified as benign or malignant; do not use if a definitive diagnosis has been established. For D43.8, 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 D43.8 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 pathology or imaging findings show a lesion that cannot be definitively classified as benign or malignant; do not use if a definitive diagnosis has been established
- •Ensure documentation specifies the exact location within the CNS (brain, spinal cord, or other specified site) and review the pathology report for any language indicating 'uncertain behavior' or 'borderline' characteristics
Clinical Significance
This code captures neoplasms of uncertain behavior in specified central nervous system locations not covered by other D43 codes, such as the cauda equina, optic nerve, or olfactory bulb. These tumors require specialized neurosurgical evaluation due to their complex anatomical relationships and potential for neurological morbidity.
Documentation Requirements
- ✓Documentation must specify the exact central nervous system location, confirmed by neuroimaging and surgical pathology.
- ✓The pathology report should describe the histological features that warrant uncertain behavior classification.
- ✓Document neurological deficits specific to the involved anatomical structure.
Commonly Confused Codes
- •D43.0-D43.4 cover specific central nervous system locations (brain regions, cranial nerves, spinal cord) and should be used when applicable.
- •D43.9 (central nervous system, unspecified) is less specific and should not be used when the site is documented.
- •C72.8 (malignant neoplasm of other specified central nervous system) is the malignant counterpart.