ICD-10-CM 2027 diagnosis code
K04.8Radicular cyst
K04.8 is a valid, billable ICD-10-CM code for radicular cyst. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Apical cyst, ICD-10 code for Periapical cyst, ICD-10 code for Dental root cyst, ICD-10 code for Periodontal cyst.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About K04.8
K04.8 is the ICD-10-CM diagnosis code for Radicular cyst. It belongs to category K04 (diseases of pulp and periapical tissues), block K00-K14 (diseases of oral cavity and salivary glands) and chapter 11 (diseases of the digestive system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within K04 (diseases of pulp and periapical tissues), K04.8 is specifically for Radicular cyst. Related codes cover pulpitis (K04.0), necrosis of pulp (K04.1), pulp degeneration (K04.2), abnormal hard tissue formation in pulp (K04.3), acute apical periodontitis of pulpal origin (K04.4), chronic apical periodontitis (K04.5), periapical abscess with sinus (K04.6), periapical abscess without sinus (K04.7) and 1 more.
The conditions in its Excludes2 note aren't part of K04.8, but may be coded alongside it if the patient has both: lateral periodontal cyst (K09.0).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC, relative weight 5.6154), DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC, relative weight 4.381), DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC, relative weight 2.7307), DRG 157 (Dental and Oral Diseases with MCC, relative weight 1.809), DRG 158 (Dental and Oral Diseases with CC, relative weight 0.9366) and DRG 159 (Dental and Oral Diseases without CC/MCC, relative weight 0.6893), in Pre-MDC and MDC 03 (Diseases and Disorders of the Ear, Nose, Mouth and Throat), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 522.8 (Radicular cyst).
Coding notes
- Apical (periodontal) cyst
- Periapical cyst
- Residual radicular cyst
- lateral periodontal cyst (K09.0)
Notes that apply from higher levels
Instructions written at a parent level also apply to K04.8.
Broader instructions also apply from Chapter 11: Diseases of the digestive system.
Alphabetic index entries
9 entriesTerms in the official ICD-10-CM index that lead to K04.8.
- Cyst (colloid) (mucous) (simple) (retention) › apical (tooth) (periodontal)
- Cyst (colloid) (mucous) (simple) (retention) › dental (root)
- Cyst (colloid) (mucous) (simple) (retention) › mandible › radicular
- Cyst (colloid) (mucous) (simple) (retention) › maxilla › radicular
- Cyst (colloid) (mucous) (simple) (retention) › periapical
- Cyst (colloid) (mucous) (simple) (retention) › periodontal
- Cyst (colloid) (mucous) (simple) (retention) › radicular (residual)
- Cyst (colloid) (mucous) (simple) (retention) › radiculodental
- Cyst (colloid) (mucous) (simple) (retention) › residual (radicular)
Codes whose notes reference K04.8
- K09Excludes2
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC PRE · Pre-MDC
MDC 03 · Diseases and Disorders of the Ear, Nose, Mouth and Throat
ICD-9-CM equivalent
Converter →- 522.8Radicular cystexact
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about K04.8
Is K04.8 billable?
- Yes. K04.8 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can K04.8 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict K04.8 as a principal diagnosis.
Is K04.8 a CC or MCC?
- No. K04.8 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does K04.8 group to?
- K04.8 is used in the MS-DRG v44.0 logic for MS-DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC), MS-DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC), MS-DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC), MS-DRG 157 (Dental and Oral Diseases with MCC), MS-DRG 158 (Dental and Oral Diseases with CC) and MS-DRG 159 (Dental and Oral Diseases without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for K04.8?
- The CMS General Equivalence Mappings map K04.8 to ICD-9-CM 522.8.