2026 ICD-10-CM Diagnosis Code K09.9Cyst of oral region, unspecified

ICD-10-CM Codes›K00–K95›K00-K14›K09

ICD-10-CM K09.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K09.9 is a billable ICD-10-CM diagnosis code for cyst of oral region, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 157 through 159. Coders also document this condition as oral cyst. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury, Diseases of mouth; excluding dental, and Nontraumatic dental conditions.

Code Identity

ICD-10-CM Code
K09.9
Billable Status
Yes — Valid for Submission
Code Describes
Cyst of oral region, unspecified
Short Description
Cyst of oral region, unspecified
Same as the full description in the CMS dataset.
Parent Code
K09
Cysts of oral region, not elsewhere classified

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK00-K14Diseases of oral cavity and salivary glands
CategoryK09Cysts of oral region, not elsewhere classified
This CodeK09.9Cyst of oral region, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Oral cyst

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Cyst(colloid) (mucous) (simple) (retention)
      • oral
        • region
    • Cyst(colloid) (mucous) (simple) (retention)
      • oral
        • soft tissue

Clinical ClassificationClinical

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

CCSR DEN001
Any dental condition including traumatic injury
Default principal diagnosis: inpatient No · outpatient No
CCSR DIG003
Diseases of mouth; excluding dental
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR DEN002
Nontraumatic dental conditions
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Mouth Disorders

Your mouth is one of the most important parts of your body. It has many different functions. It allows you to:

Read the full article at MedlinePlus

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

Convert K09.9 to ICD-9-CMHistory

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

ICD-9-CM
528.4 Oral soft tissue cyst
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 K09.9Overview

Is K09.9 (Cysts of oral region, not elsewhere classified) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cyst of oral region, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K09.9 group to?

When cyst of oral region, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 157, 158, 159, with relative weights from 0.7085 to 1.7168 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of K09.9?

Under the General Equivalence Mappings, cyst of oral region, unspecified converts to ICD-9-CM 528.4 (oral soft tissue cyst). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.