C71.9 Malignant neoplasm of brain, unspecified

The ICD-10-CM code for Malignant neoplasm of brain, unspecified is C71.9 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

2: Neoplasms (C00-D49)

Section

C69-C72: Malignant neoplasms of eye, brain and other parts of central nervous system (C69-C72)

Category C71

11 codes (10 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to C71.9:

• Astroglioma › unspecified site
• Astrocytoma (cystic) › unspecified site
• Ependymoma (epithelial) (malignant) › unspecified site
• Glioblastoma (multiforme) › unspecified site
• Gemistocytoma › unspecified site
• Astroblastoma › unspecified site
• Ependymoblastoma › unspecified site
• Glioma (malignant) › unspecified site

U.S. Hospital Utilization

• An estimated 25,620 U.S. inpatient stays in 2023 included C71.9 among the documented diagnoses.
• 10,855 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)