2026 ICD-10-CM Diagnosis Code M27.40Unspecified cyst of jaw

ICD-10-CM Codes›M00–M99›M26-M27›M27

ICD-10-CM M27.40
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M27.40 is a billable ICD-10-CM diagnosis code for unspecified cyst of jaw. 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 cyst of jaw. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury, Disorders of jaw, and Nontraumatic dental conditions.

Code Identity

ICD-10-CM Code
M27.40
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified cyst of jaw
Short Description
Unspecified cyst of jaw
Same as the full description in the CMS dataset.
Parent Code
M27.4
Other and unspecified cysts of jaw

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM26-M27Dentofacial anomalies [including malocclusion] and other disorders of jaw
CategoryM27Other diseases of jaws
This CodeM27.40Unspecified cyst of jaw

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cyst of jaw
  • Hemorrhagic cyst of jaw
  • Mandibular cyst
  • Maxillary cyst

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Cyst of jaw NOS

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)
      • alveolar process (jaw bone)
    • Cyst(colloid) (mucous) (simple) (retention)
      • bone (local) NEC
        • specified type NEC
          • jaw
    • Cyst(colloid) (mucous) (simple) (retention)
      • jaw (bone)
    • Cyst(colloid) (mucous) (simple) (retention)
      • mandible
    • Cyst(colloid) (mucous) (simple) (retention)
      • maxilla
    • Cyst(colloid) (mucous) (simple) (retention)
      • solitary
        • jaw

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 MUS029
Disorders of jaw
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR DEN002
Nontraumatic dental conditions
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Jaw Injuries and Disorders

Your jaw is a set of bones that holds your teeth. It includes:

Read the full article at MedlinePlus

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

Convert M27.40 to ICD-9-CMHistory

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

ICD-9-CM
526.2 Cysts of jaws NEC
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 M27.40Overview

Is M27.40 (Other and unspecified cysts of jaw) a billable code?

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

What MS-DRG does M27.40 group to?

When unspecified cyst of jaw 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 M27.40?

Under the General Equivalence Mappings, unspecified cyst of jaw converts to ICD-9-CM 526.2 (cysts of jaws NEC). 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.