C41.9 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 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

2: Neoplasms (C00-D49)

Section

C40-C41: Malignant neoplasms of bone and articular cartilage (C40-C41)

Category C41

7 codes (6 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to C41.9:

• Osteitis › deformans › in (due to) › malignant neoplasm of bone (see also, Neoplasm, malignant, by site)

U.S. Hospital Utilization

• An estimated 5,375 U.S. inpatient stays in 2023 included C41.9 among the documented diagnoses.
• 465 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Tx of primary site (TOC entry)

a. Admission/Encounter for treatment of primary site ............................................................. 33

Tx of secondary site (TOC entry)

b. Admission/Encounter for treatment of secondary site .......................................................... 33

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)