2026 ICD-10-CM Diagnosis Code C41.9Malignant neoplasm of bone and articular cartilage, unspecified

ICD-10-CM Codes›C00–D49›C40-C41›C41

ICD-10-CM C41.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C41.9 is a billable ICD-10-CM diagnosis code for malignant neoplasm of bone and articular cartilage, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 542 through 544. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 25 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bone cancer.

For Medicare Advantage risk adjustment, C41.9 maps to CMS-HCC Category 21 (Lymphoma and Other Cancers) under the V28 model, adding a risk factor of about 0.671 for a community, non-dual, aged beneficiary in payment year 2026.

Code Identity

ICD-10-CM Code
C41.9
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of bone and articular cartilage, unspecified
Short Description
Malignant neoplasm of bone and articular cartilage, unsp
Parent Code
C41
Malignant neoplasm of bone and articular cartilage of other and unspecified sites

Code Classification

ChapterC00–D49Neoplasms
SectionC40-C41Malignant neoplasms of bone and articular cartilage
CategoryC41Malignant neoplasm of bone and articular cartilage of other and unspecified sites
This CodeC41.9Malignant neoplasm of bone and articular cartilage, unspecified

Medicare Risk Adjustment (HCC)Billing

C41.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.

CMS-HCC V28 Category (Payment Model)
HCC 21— Lymphoma and Other Cancers
Payment HCC · PY 2026 one of 463 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.671
community, non-dual, aged · ranges 0.493–0.739 across segments
Hierarchy
Superseded by HCC 17, HCC 18, HCC 19, and HCC 20
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 10
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 10 · ESRD (V21): HCC 10 · ESRD (V24): HCC 10
ESRD V21 weights: 0.136 dialysis, 0.451–0.668 functioning graft · ESRD V24 weights: 0.111 dialysis, 0.467–0.780 functioning graft
Part D (RxHCC)
RxHCC 22 — Prostate, Breast, Bladder, and Other Cancers and Tumors
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carcinoma of bone, connective tissue, skin and breast
  • Chondrosarcoma
  • Chondrosarcoma of bone
  • Clear cell chondrosarcoma
  • Conventional osteosarcoma
  • Dedifferentiated chondrosarcoma
  • Diaphyseal medullary stenosis with bone malignancy
  • Disseminated Langerhans cell histiocytosis of bone
  • Ewing's sarcoma of bone
  • Extraskeletal mesenchymal chondrosarcoma
  • Extraskeletal myxoid chondrosarcoma
  • High-grade surface osteosarcoma
  • Langerhans cell histiocytosis, disseminated
  • Large cell Ewing sarcoma of bone
  • Local recurrence of malignant neoplasm of bone
  • Low-grade central osteosarcoma
  • Macrocytosis - no anemia
  • Malignant giant cell tumor of bone
  • Malignant neoplasm of articular cartilage
  • Malignant neoplasm of bone
  • Malignant neoplasm of bone, connective tissue, skin and breast
  • Malignant neoplasm of skeletal system
  • Malignant neoplasm of vertebra
  • Mesenchymal chondrosarcoma
  • Metastatic extraskeletal osteosarcoma
  • Metastatic malignant neoplasm to articular cartilage
  • Metastatic malignant neoplasm to clavicle
  • Metastatic malignant neoplasm to long bone of upper limb
  • Metastatic malignant neoplasm to rib
  • Metastatic malignant neoplasm to sternum
  • Metastatic malignant neoplasm to vertebral column
  • Metastatic osteosarcoma to articular cartilage of clavicle
  • Metastatic osteosarcoma to articular cartilage of rib
  • Metastatic osteosarcoma to articular cartilage of sternum
  • Metastatic osteosarcoma to articular cartilage of vertebra
  • Metastatic osteosarcoma to bone
  • Metastatic osteosarcoma to bone of clavicle
  • Metastatic osteosarcoma to bone of head
  • Metastatic osteosarcoma to bone of rib
  • Metastatic osteosarcoma to bone of sternum
  • Metastatic osteosarcoma to bone of vertebra
  • Non-anemic red cell disorder
  • Osteosarcoma
  • Osteosarcoma of articular cartilage of clavicle
  • Osteosarcoma of articular cartilage of rib
  • Osteosarcoma of articular cartilage of sternum
  • Osteosarcoma of articular cartilage of vertebra
  • Osteosarcoma of bone
  • Osteosarcoma of bone of clavicle
  • Osteosarcoma of bone of head
  • Osteosarcoma of bone of rib
  • Osteosarcoma of bone of upper limb
  • Osteosarcoma of bone of vertebra
  • Osteosarcoma of sternum
  • Osteosarcoma, limb anomalies, erythroid macrocytosis syndrome
  • Overlapping malignant neoplasm of bone and articular cartilage
  • Parosteal osteosarcoma
  • Periosteal chondrosarcoma
  • Periosteal osteosarcoma
  • Primary chondrosarcoma of articular cartilage
  • Primary chondrosarcoma of bone
  • Primary Ewing sarcoma of bone
  • Primary large cell Ewing sarcoma of bone
  • Primary malignant neoplasm of articular cartilage
  • Primary malignant neoplasm of bone
  • Primary osteosarcoma
  • Primary osteosarcoma of bone
  • Sarcoma of bone
  • Sarcoma of bone and connective tissue
  • Sarcoma of clavicle
  • Sarcoma of rib
  • Sarcoma of sternum
  • Sarcoma of vertebra
  • Small cell osteosarcoma
  • Telangiectatic osteosarcoma

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO023
Bone cancer
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Osteosarcoma

    a sarcoma originating in bone-forming cells, affecting the ends of long bones. it is the most common and most malignant of sarcomas of the bones, and occurs chiefly among 10- to 25-year-old youths. (from stedman, 25th ed)

  • Osteosarcoma, Juxtacortical

    a form of osteogenic sarcoma of relatively low malignancy, probably arising from the periosteum and initially involving cortical bone and adjacent connective tissue. it occurs in middle-aged as well as young adults and most commonly affects the lower part of the femoral shaft. (stedman, 25th ed)

  • Chondrosarcoma

    a slowly growing malignant neoplasm derived from cartilage cells, occurring most frequently in pelvic bones or near the ends of long bones, in middle-aged and old people. most chondrosarcomas arise de novo, but some may develop in a preexisting benign cartilaginous lesion or in patients with enchondromatosis. (stedman, 25th ed)

  • Chondrosarcoma, Clear Cell

    a chondrosarcoma of adolescence to old age of the proximal epiphyses of long bones. it has variably clear cytoplasm of the mostly neoplastic chondrocytes with little intervening matrix.

  • Chondrosarcoma, Mesenchymal

    a rare aggressive variant of chondrosarcoma, characterized by a biphasic histologic pattern of small compact cells intermixed with islands of cartilaginous matrix. mesenchymal chondrosarcomas have a predilection for flat bones; long tubular bones are rarely affected. they tend to occur in the younger age group and are highly metastatic. (devita jr et al., cancer: principles & practice of oncology, 3d ed, p1456)

  • Enchondromatosis

    benign growths of cartilage in the metaphyses of several bones.

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
bone (periosteum)C41.9C79.51–D16.9D48.0D49.2
bone (periosteum) › cartilage NECC41.9C79.51–D16.9D48.0D49.2
bone (periosteum) › cuneiformC41.9C79.51–D16.9D48.0D49.2
cartilage (articular) (joint) NEC [See Also: Neoplasm, bone]C41.9C79.51–D16.9D48.0D49.2
joint NEC [See Also: Neoplasm, bone]C41.9C79.51–D16.9D48.0D49.2
skeleton, skeletal NECC41.9C79.51–D16.9D48.0D49.2

Patient EducationClinical

Cancer

Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should.

The full article covers:

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Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C41.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
170.9 Malig neopl bone NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C41.9Overview

What is the ICD-10 code for malignant neoplasm of bone and articular cartilage, unspecified?

The ICD-10-CM code for malignant neoplasm of bone and articular cartilage, unspecified is C41.9 (sometimes written as C419). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is C41.9 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of bone and articular cartilage, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C41.9 group to?

When malignant neoplasm of bone and articular cartilage, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 542, 543, 544, with relative weights from 0.7546 to 1.7665 depending on complications. Higher weights mean higher Medicare reimbursement.

Is C41.9 a CC or MCC?

CMS lists C41.9 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 25 closely related codes in its exclusion list.

What is the ICD-9 equivalent of C41.9?

Under the General Equivalence Mappings, malignant neoplasm of bone and articular cartilage, unspecified converts to ICD-9-CM 170.9 (malig neopl bone NOS). The mapping is approximate, so confirm the match fits the documentation.

What HCC is C41.9?

C41.9 (malignant neoplasm of bone and articular cartilage, unspecified) maps to CMS-HCC Category 21 (Lymphoma and Other Cancers), commonly written as HCC 21, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 10 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.

Does C41.9 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, C41.9 adds a risk adjustment factor of about 0.671 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.493 to 0.739 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, and HCC 20) supersedes it when both are reported. See the full factor table on the HCC 21 category page.