2026 ICD-10-CM Diagnosis Code S90.424SBlister (nonthermal), right lesser toe(s), sequela

ICD-10-CM Codes›S00–T88›S90-S99›S90

ICD-10-CM S90.424S
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S90.424S is a billable ICD-10-CM diagnosis code for blister (nonthermal), right lesser toe(s), sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 604 through 605. The code is exempt from POA reporting. Coders also document this condition as blister of foot with infection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.

Code Identity

ICD-10-CM Code
S90.424S
Billable Status
Yes — Valid for Submission
Code Describes
Blister (nonthermal), right lesser toe(s), sequela
Short Description
Blister (nonthermal), right lesser toe(s), sequela
Same as the full description in the CMS dataset.
Parent Code
S90.424
Blister (nonthermal), right lesser toe(s)

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS90-S99Injuries to the ankle and foot
CategoryS90Superficial injury of ankle, foot and toes
This CodeS90.424SBlister (nonthermal), right lesser toe(s), sequela

Present on Admission (POA)Billing

S90.424S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Blister of foot with infection
  • Blister of toe with infection
  • Right foot blister with infection
  • Right lesser toe blister with infection
  • Traumatic blister of lesser toe
  • Traumatic blister of right foot
  • Traumatic blister of right lesser toe
  • Traumatic blister of toe

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Superficial injury of ankle, foot and toes (S90). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ073
Injury, sequela
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Blister

    visible accumulations of fluid within or beneath the epidermis.

  • Herpes Labialis

    herpes simplex, caused by type 1 virus, primarily spread by oral secretions and usually occurring as a concomitant of fever. it may also develop in the absence of fever or prior illness. it commonly involves the facial region, especially the lips and the nares. (dorland, 27th ed.)

Patient EducationClinical

Blisters

Blisters are fluid-filled sacs on the outer layer of your skin. They form because of rubbing, heat, or diseases of the skin. They are most common on your hands and feet.

The full article covers:

  • What are blisters?
  • What causes blisters?
  • What are the treatments for blisters?
  • Can blisters be prevented?

Read the full article at MedlinePlus

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

Convert S90.424S to ICD-9-CMHistory

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

ICD-9-CM
906.2 Late eff superficial inj
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 S90.424SOverview

Is S90.424S (Blister (nonthermal), right lesser toe(s)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report blister (nonthermal), right lesser toe(s), sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character S in S90.424S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the blister (nonthermal), right lesser toe(s) itself has resolved, not the original event.

What MS-DRG does S90.424S group to?

When blister (nonthermal), right lesser toe(s), sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, with relative weights from 0.9160 to 1.4721 depending on complications. Higher weights mean higher Medicare reimbursement.

Is S90.424S exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for blister (nonthermal), right lesser toe(s), sequela on inpatient claims.

What is the ICD-9 equivalent of S90.424S?

Under the General Equivalence Mappings, blister (nonthermal), right lesser toe(s), sequela converts to ICD-9-CM 906.2 (late eff superficial inj). 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.