What is ICD-10 code C41.9?

C41.9 is the ICD-10-CM diagnosis code for Malignant neoplasm of bone and articular cartilage, unspecified. Cancer of bone or cartilage when the specific bone location is not identified or specified. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C41.9 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C41.9 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. C41.9 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. C41.9 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.

Which HCC does C41.9 map to under V28?

C41.9 maps to CMS-HCC V28 HCC 21 (Lymphoma and Other Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C41.9: Malignant neoplasm of bone

C41.9 maps to CMS-HCC V28 21. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

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Code lookupC41.9

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of bone and articular cartilage (C40-C41)

C41.9

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

Malignant neoplasm of bone and articular cartilage, unspecified

Cancer of bone or cartilage when the specific bone location is not identified or specified.

Buddy Insight

Primary malignant neoplasm of bone and articular cartilage, unspecified site.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 21

Lymphoma and Other Cancers

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 010

HHS-HCC 010 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 22

Prostate, Breast, Bladder, an...

Code-level coefficient reference

Code Book Path

Official

C41Malignant neoplasm of bone and articular cartilage of other and unspecified sites C41.9Malignant neoplasm of bone and articular cartilage, unspecified

Inclusion Terms

Official

No inclusion terms are included in this display for C41.9. Check the code and parent instructions in the Code Book.

Excludes 2

Official

No Excludes 2 notes are included in this display for C41.9. Check the code and parent instructions in the Code Book.

Related Codes

Official

C41.0Malignant neoplasm of bones of skull and face C41.1Malignant neoplasm of mandible C41.2Malignant neoplasm of vertebral column C41.3Malignant neoplasm of ribs, sternum and clavicle C41.4Malignant neoplasm of pelvic bones, sacrum and coccyx

Includes

Official

malignant neoplasm of cartilage (articular) (joint)Inherited from C40-C41
malignant neoplasm of periosteumInherited from C40-C41

Excludes 1

Official

malignant neoplasm of bone marrow NOS (C96.9)Inherited from C40-C41, C41
malignant neoplasm of synovia (C49.-)Inherited from C40-C41, C41
malignant neoplasm of bones of limbs (C40.-)Inherited from C40-C41, C41
malignant neoplasm of cartilage of ear (C49.0)Inherited from C40-C41, C41
malignant neoplasm of cartilage of eyelid (C49.0)Inherited from C40-C41, C41
malignant neoplasm of cartilage of larynx (C32.3)Inherited from C40-C41, C41
malignant neoplasm of cartilage of limbs (C40.-)Inherited from C40-C41, C41
malignant neoplasm of cartilage of nose (C30.0)Inherited from C40-C41, C41

Code First

Official

No Code First sequencing instructions are included in this display for C41.9. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C41.9. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C41.9. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Provider query for specific bone site — this code represents documentation failure

Histologic confirmation of malignancy

Primary vs. metastatic origin confirmed

Any imaging available that could identify the bone site

MEAT Support

HCC Buddy guidance

Provider query for specific bone site — this code represents documentation failure

Histologic confirmation of malignancy

Primary vs. metastatic origin confirmed

Any imaging available that could identify the bone site

Audit Caution

HCC Buddy guidance

Defaulting to this code when more specific site information exists in imaging, pathology, or surgical reports

Not querying the provider for additional site-specific details

Using this code for bone metastases from known primary cancers — use C79.51 instead

Using this code when the coder has not reviewed all available diagnostic reports

Common Mistakes

HCC Buddy guidance

C40.90 — Unspecified bones of unspecified limb; use when it is at least known to be a limb bone

C41.0 through C41.4 — Specific axial skeleton sites; always preferred over C41.9

C79.51 — Secondary malignant neoplasm of bone; for metastatic disease, not primary

D49.2 — Neoplasm of unspecified behavior of bone; when malignancy is not yet confirmed

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 C41.9 an HCC code?

Yes. C41.9 (Malignant neoplasm of bone and articular cartilage, unspecified) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. 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: C41.9 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C41.9
Description: Malignant neoplasm of bone and articular cartilage, unspecified
HCC (V28): HCC 21 — Lymphoma and Other Cancers
RAF reference coefficient: 0.671
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers

0.671

ESRDHCC 10, Lymphoma and Other Cancers

Not separately weighted

RxHCCHCC 22, Prostate, Breast, Bladder, and Other Cancers and Tumors

Not separately weighted

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 C41.9 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C41.9

For C41.9, 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

C41.9 is the ICD-10-CM diagnosis code for malignant neoplasm of bone and articular cartilage, unspecified. Cancer of bone or cartilage when the specific bone location is not identified or specified. C41.9 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of bone and articular cartilage (c40-c41).

Under the CMS-HCC V28 risk adjustment model, C41.9 maps to Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. No V24 mapping is shown for C41.9; 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.

This is the least specific bone cancer code; use only when no other information is available. For C41.9, 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 C41.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is the least specific bone cancer code; use only when no other information is available
•Always query provider for more specific anatomical location to allow for more precise coding

Clinical Significance

Primary malignant neoplasm of bone and articular cartilage, unspecified site. This is the most nonspecific code in the bone malignancy category and should only be used when the anatomic site truly cannot be determined. This code should trigger a provider query for more specific site information to improve documentation quality and audit defensibility.

Documentation Requirements

✓Provider query for specific bone site — this code represents documentation failure
✓Histologic confirmation of malignancy
✓Primary vs. metastatic origin confirmed
✓Any imaging available that could identify the bone site
✓Clinical rationale for why the site cannot be specified
✓Treatment plan and disease status

Commonly Confused Codes

•C40.90: Unspecified bones of unspecified limb; use when it is at least known to be a limb bone
•C41.0 through C41.4: Specific axial skeleton sites; always preferred over C41.9
•C79.51: Secondary malignant neoplasm of bone; for metastatic disease, not primary
•D49.2: Neoplasm of unspecified behavior of bone; when malignancy is not yet confirmed