ICD-10-CM 2027 diagnosis code
B09Unspecified viral infection characterized by skin and mucous membrane lesions
B09 is a valid, billable ICD-10-CM code for unspecified viral infection characterized by skin and mucous membrane lesions. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Unsp viral infection with skin and mucous membrane lesions
Looking up by condition? See ICD-10 code for Roseola, ICD-10 code for Enanthema.
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 B09
B09 is the ICD-10-CM diagnosis code for unspecified viral infection characterized by skin and mucous membrane lesions. It belongs to block B00-B09 (viral infections characterized by skin and mucous membrane lesions) and chapter 1 (certain infectious and parasitic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
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 865 (Viral Illness with MCC, relative weight 1.3485) and DRG 866 (Viral Illness without MCC, relative weight 0.8692), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), 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 057.8 (other specified viral exanthemata) and 057.9 (viral exanthem, unspecified).
Coding notes
- Viral enanthema NOS
- Viral exanthema NOS
Notes that apply from higher levels
Instructions written at a parent level also apply to B09.
Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.
Alphabetic index entries
7 entriesTerms in the official ICD-10-CM index that lead to B09.
- Enanthema, viral
- Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › postexanthematous NEC
- Exanthem, exanthema › viral, virus
- Infection, infected, infective (opportunistic) › virus, viral NOS › exanthem NOS
- Keratitis (nodular) (nonulcerative) (simple) (zonular) › in (due to) › exanthema
- Keratoconjunctivitis › in exanthema
- Roseola
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 18 · Infectious and Parasitic Diseases, Systemic or Unspecified Sites
ICD-9-CM equivalent
Converter →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 B09
Is B09 billable?
- Yes. B09 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can B09 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict B09 as a principal diagnosis.
Is B09 a CC or MCC?
- No. B09 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does B09 group to?
- B09 is used in the MS-DRG v44.0 logic for MS-DRG 865 (Viral Illness with MCC) and MS-DRG 866 (Viral Illness without 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 B09?
- The CMS General Equivalence Mappings map B09 to ICD-9-CM 057.8 and 057.9.